Learning to Tune the Holley Sniper

[Papa]

Let's see if we can give this thread legs! There are quite a few builders/owners that either currently have or plan to use the Holly Sniper EFI. I'm one of them, and I'd love to learn how to tune the system. I'm ready to be the tester of your expert advice and document what I learn in this thread. So, if you have already gotten over the learning curve and would like to help teach me (and others) the ropes, let's get started.

First, some basic information about my engine:

BluePrint Engines (BPE) 347 purchased in 2017:

Fuel Delivery:
- Fuel Injected, Holley Sniper EFI

Manifold:
- Edlebrock Polished Air Gap

Ignition/Distributor:
- MSD

Block:
- 302ci, 2 bolt main, bored .040
- 1-piece rear main seal

Rotating Assembly:
- Cast steel crank
- 3.4” stroke and Forged 5.4” rods
- 150,000 psi rod bolts
- Forged pistons
- Hastings Moly rings
- Balanced rotating assembly
- High volume oil pump
- Hydraulic roller camshaft
- Heavy duty double roller timing set

Heads:
- BluePrint Performance Aluminum
- 58cc chamber
- Hardened retainers and springs
- 2.02 swirl polished intake valves
- 1.60 swirl polished exhaust valves
(BP Aluminum Head Part# HP9009)

Cam Specs:
- Roller, .543 Intake
- .554 Exhaust & 218 Intake
- 226 Exhaust duration @ .050 - 112 degree lobe separation

My car has been on the road for less than 1000 miles and runs pretty well. The idle is set at 900 rpm, and if possible, I'd like to bring that down a bit as long as the car continues to run well at a lower idle speed. While driving, any lift of the accelerator results in popping in the exhaust. I don't mind a little crackle, but it's excessive as it stands right now and I'd like to clean that up. My measured fuel economy on the highway for one trip put me at about 14 mpg, which I can definitely live with. However, if I can keep the performance and get a little more range on a tank of gas, I'd welcome that, too.

To date, I haven't done any data logging, but I can share some captures of my base fuel map, and learning map.

Base Fuel Map:

https://thefactoryfiveforum.com/attachment.php?attachmentid=127746&d=1588619949

Base Fuel Graph:

https://thefactoryfiveforum.com/attachment.php?attachmentid=127748&d=1588619967

Learn Fuel Map:

https://thefactoryfiveforum.com/attachment.php?attachmentid=127747&d=1588619960

The Decel Fuel Cutoff control is currently disabled by default. I've read that the base fuel table should be finished before enabling this control.

https://thefactoryfiveforum.com/attachment.php?attachmentid=127749&d=1588619976

Once I do enable it, what parameters would I want to start with? It seems that the defaults of 0 would engage this control as soon as I lift on the accelerator and would reenable fuel at any RPM above idle. I've also read that this control only triggers when the rpm is above 3000, so it may not fully address my decel popping issue which is happening at pretty much any rpm.

[TMartinLVNV]

This looks like fun. I'll be watching this as I'm a few months behind you.

Thanks Dave.

[BradCraig]

At some point, you'll want to transfer that learn to base. As far as the Fuel decel wait time, holley recommends .5 to 2.0. and 300 RPM for manual transmissions. I have 1Sec and 400 RPM, but your settings may be different.

If you don't have the full manual, download: https://documents.holley.com/199r11031r.pdf There is also a great Holly Sniper support group on FB.

[FF33rod]

and another one following.... not driving yet but engine is running. Very similar engine specs to you Papa - a bit more aggressive cam (0.542 int./0.563 exh. lift, 224 int./232 exh duration, 112 LSA), same intake, ignition system is full hyperspark with timing control, I'm using AFR 195 heads with 58cc chamber. You didn't mention your compression ratio, mine is around 10.7 as the pistons are -4cc as I recall.

The Holley Sniper forum isn't a bad resource. There are a few helpful regulars there if you post issues and setup/log files.

One bookmark that I made was for this basic tuning thread, some helpful references in there https://forums.holley.com/showthread.php?47404-Basic-Tuning&highlight=Basic+tuning

There is also some helpful information here: https://www.efisystempro.com/efi-pro-hangout/holley-sniper-efi-instruction note that EFI System Pro also has some good accessories for the Sniper including a progressive throttle linkage which brings on the secondaries at about 40% instead of right away, makes the throttle much less twitchy.

Steve

[Papa]

Okay. I transferred the learn map to the base map and smoothed everything and here is what I have now:

https://thefactoryfiveforum.com/attachment.php?attachmentid=127767&d=1588636811

https://thefactoryfiveforum.com/attachment.php?attachmentid=127768&d=1588636823

It's significantly different than the original base map. I haven't loaded into the car yet as I'd like to get some comments from the experts first. I did back-up the original config file before making any changes, so I can always go back to a known starting point.

[Papa]

and another one following.... not driving yet but engine is running. Very similar engine specs to you Papa - a bit more aggressive cam (0.542 int./0.563 exh. lift, 224 int./232 exh duration, 112 LSA), same intake, ignition system is full hyperspark with timing control, I'm using AFR 195 heads with 58cc chamber. You didn't mention your compression ratio, mine is around 10.7 as the pistons are -4cc as I recall.

The Holley Sniper forum isn't a bad resource. There are a few helpful regulars there if you post issues and setup/log files.

One bookmark that I made was for this basic tuning thread, some helpful references in there https://forums.holley.com/showthread.php?47404-Basic-Tuning&highlight=Basic+tuning

There is also some helpful information here: https://www.efisystempro.com/efi-pro-hangout/holley-sniper-efi-instruction note that EFI System Pro also has some good accessories for the Sniper including a progressive throttle linkage which brings on the secondaries at about 40% instead of right away, makes the throttle much less twitchy.

Steve

My compression ratio is 10:1. I've been lurking on the Sniper forum and will check out the additional references.

Dave

[bobl]

Be careful on the smoothing. If you have areas that have not learned it will more or less average them in with other areas that have learned and can skew the table. I would save the smoothing until it's well sorted out.

[bobl]

I never had much luck getting the cut fuel on decel to work cleanly. These cars are so light that you can end up cruising at 0 tps so the ecu doesn't know what is going on. Of course no fuel will stop the popping, but it's hard to get the transition correct. I gave up trying to make it work. But it doesn't hurt to play with it, just make sure and save a backup tune. Since your ecu is not controlling timing, disregard my comments on the other thread. I would get some data logs and see what the A/F is doing. See if you can post a copy of your config file and a data log of just normal driving. I would like to study it a bit. What altitude are you driving at? I know it's pretty high so the tables will be different than if you were at sea level.

[Papa]

Be careful on the smoothing. If you have areas that have not learned it will more or less average them in with other areas that have learned and can skew the table. I would save the smoothing until it's well sorted out.

Thanks, Bob.

Here is what the map looks like (learn-to-base) unsmoothed:

https://thefactoryfiveforum.com/attachment.php?attachmentid=127786&d=1588647217

https://thefactoryfiveforum.com/attachment.php?attachmentid=127787&d=1588647233

Dave

[Papa]

I never had much luck getting the cut fuel on decel to work cleanly. These cars are so light that you can end up cruising at 0 tps so the ecu doesn't know what is going on. Of course no fuel will stop the popping, but it's hard to get the transition correct. I gave up trying to make it work. But it doesn't hurt to play with it, just make sure and save a backup tune. Since your ecu is not controlling timing, disregard my comments on the other thread. I would get some data logs and see what the A/F is doing. See if you can post a copy of your config file and a data log of just normal driving. I would like to study it a bit. What altitude are you driving at? I know it's pretty high so the tables will be different than if you were at sea level.

Bob,

I'll see if I can get a little time in the car over the next couple of days after work to capture some data logs. My home is right at 6,100' elevation. Local driving around town and surrounding areas will vary +/- a few hundred feet.

Thanks,
Dave

[Papa]

I did a data log today from cold start and then over about a 15 mile loop. Here is what the AFR plot looks like:

https://thefactoryfiveforum.com/attachment.php?attachmentid=127812&d=1588726376

What would be the best way to get the config and data log files posted? The data log is pretty large (62MB). Zipped, the compressed file is 7.7MB, still way too large to upload to the forum.

Thanks,
Dave

[FF33rod]

Maybe a dropbox shared (public) folder?

All those spikes are interesting, would be good to see what's happening with RPM etc at the same time. I guess that's all in the log

[bobl]

I did a data log today from cold start and then over about a 15 mile loop. Here is what the AFR plot looks like:

https://thefactoryfiveforum.com/attachment.php?attachmentid=127812&d=1588726376

What would be the best way to get the config and data log files posted? The data log is pretty large (62MB). Zipped, the compressed file is 7.7MB, still way too large to upload to the forum.

Thanks,
Dave

That's a pretty long data log so it makes it hard to break down what's going on. I like to make them just a couple of minutes long under a somewhat controlled driving cycle. That way you can kind of correlate what you see with what you experienced while driving. I have no clue on how to post a file like that so others can see it. You should be able to attach the config file as they are not very large.

[Papa]

Bob,

I did find a way to reduce the large file to a shorter snippet. Here is a picture of a shorter version with some labels:

https://thefactoryfiveforum.com/attachment.php?attachmentid=127833&d=1588770196

I was able to attach my config file, but even the reduced data log is still too large for the forum file upload size limit. It's only a little over 600K but the forum limit for zip files is 488k. I can reduce it more if you let me know what portion you are most interested in.

Thanks,
Dave

[weendoggy]

I agree on the data logs. Shorter is better. Also, when sending data logs, send the file tune that was used during that log. I run a Terminator HP but it's similar to what you're using. You can email me the log and tune if you want. Biggest thing you need to do is get it running where you want then do a transfer after a lot of driving. Too much will skew the file. The AF ratio is the bible. The timing table is next to fine tune. jmo

[bobl]

email the data log to me also. boblloyd51@yahoo.com

[Papa]

email the data log to me also. boblloyd51@yahoo.com

Data file and config file are on their way.

Thanks again,
Dave

[Papa]

I agree on the data logs. Shorter is better. Also, when sending data logs, send the file tune that was used during that log. I run a Terminator HP but it's similar to what you're using. You can email me the log and tune if you want. Biggest thing you need to do is get it running where you want then do a transfer after a lot of driving. Too much will skew the file. The AF ratio is the bible. The timing table is next to fine tune. jmo

If you would like to PM me your e-mail, I'd be happy to provide my files to you as well.

Thanks,
Dave

BTW: I like the BOC quote in your signature. One of my all time favorite albums.

[Papa]

As I continue to research my popping issue, I came across an interesting thread on the Holley Sniper forum: https://forums.holley.com/showthread.php?23168-Sniper-going-lean-on-deceleration/page2

The description of the issue seems to match what I'm seeing with the AFR jumping on deceleration indicating a lean condition if I understand what I'm reading. The parameter that the thread recommends adjusting is the Minimum Injector Opening Time (MIOT).


I can vouch for the value of testing for the correct Minimum Injector Opening Time (MIOT), as I too would go 20+ AFR on coast, and then as the RPM neared idle, it would swing way rich as the ECU worked to catch up. The baseline was 1.20 msec, and once I narrowed down through trial & error, that 1.70 msec was too high (coast AFR went to 12), and 1.60 msec was too low (coast AFR went to 20). I settled on 1.64 msec. I was surprised at how much of an impact just .01 msec would have. I don't think the handheld is setup to adjust this value, so you'll really need the cable to hook up to a laptop. It could be done via the SD card, transferring back & forth from the handheld and the laptop, but what a PITA that would be.

My value is at the default of 1.20 msec and it would seem I want to start increasing the value until I get the AFR into the desired range where these spikes are occurring. Should I try this before doing anything else? In my line of work, I understand the value in only making one change at a time when tuning a software algorithm. I think if I can eliminate the popping, I would have an easier time focusing on the fuel map tuning.

Dave

[bobl]

As I continue to research my popping issue, I came across an interesting thread on the Holley Sniper forum: https://forums.holley.com/showthread.php?23168-Sniper-going-lean-on-deceleration/page2

The description of the issue seems to match what I'm seeing with the AFR jumping on deceleration indicating a lean condition if I understand what I'm reading. The parameter that the thread recommends adjusting is the Minimum Injector Opening Time (MIOT).



My value is at the default of 1.20 msec and it would seem I want to start increasing the value until I get the AFR into the desired range where these spikes are occurring. Should I try this before doing anything else? In my line of work, I understand the value in only making one change at a time when tuning a software algorithm. I think if I can eliminate the popping, I would have an easier time focusing on the fuel map tuning.

Dave

Just looked at your log. It does appear to be going very lean at the peaks. What is interesting though is the pulse width is still around 1.5, well above the 1.2 minimum setting. It almost appears like there is an exhaust leak or something disturbing the 02 readings. Where is your 02 sensor mounted? I'm kind of thinking those lean spikes are a result of the popping rather than a cause.
Certainly try raising the minimum open time and see the results. But it can also cause overly rich conditions where you don't want them. There are places in your log where a 1.5 pulse width results in the correct A/F, so if you changed the minimum to 1.65 as is mentioned on the Sniper forum it would be very rich at those points. I know Geoff H played with those settings some but I don't remember what he ended up with.

[Papa]

Just looked at your log. It does appear to be going very lean at the peaks. What is interesting though is the pulse width is still around 1.5, well above the 1.2 minimum setting. It almost appears like there is an exhaust leak or something disturbing the 02 readings. Where is your 02 sensor mounted? I'm kind of thinking those lean spikes are a result of the popping rather than a cause.
Certainly try raising the minimum open time and see the results. But it can also cause overly rich conditions where you don't want them. There are places in your log where a 1.5 pulse width results in the correct A/F, so if you changed the minimum to 1.65 as is mentioned on the Sniper forum it would be very rich at those points. I know Geoff H played with those settings some but I don't remember what he ended up with.

Bob,

Thanks for looking at the data. This is certainly a great example of how you can't just look at one aspect of the system in isolation and how all the different pieces fit together. Before I start changing anything, I'll give the header bolts another round of snugging and see if that does anything to improve the situation. My O2 sensor is in a collector in the passenger side header.

https://thefactoryfiveforum.com/attachment.php?attachmentid=85406&d=1525487679

I won't have time to get at this until the weekend, but let's rule out a leak before chasing things in the computer.

[weendoggy]

Dave,
Looking at your collector setup, please tell me those tack welds aren't the only thing making the system tight. You can have a LOT of air sneaking in through that collector seam(s) to cause the fresh air intake on the exhaust vacuum pull. That collector seam should be welded 360°. I know it sounds lame, but you have to take care of basics first. Looking at your logs I tend to agree with Bob on results.

[Papa]

Dave,
Looking at your collector setup, please tell me those tack welds aren't the only thing making the system tight. You can have a LOT of air sneaking in through that collector seam(s) to cause the fresh air intake on the exhaust vacuum pull. That collector seam should be welded 360°. I know it sounds lame, but you have to take care of basics first. Looking at your logs I tend to agree with Bob on results.

I asked that very same question when I received them from GP Headers and they assured me that they are okay and that they crimp them. You can see the dimple at each of the mating points on the collector. I could pull them off (not fun) and have them welded locally or I could try to get the new style headers that FFR is offering, which might address a driver's side pipe fitment issue I have at the same time. I've had several sets of headers on the car throughout the build -- loooong story.

[weendoggy]

OK, I'm going to ask the dumb question then, "if they ARE dimpled and suppose to be tight, why are they tack welded"? I'm not saying that this is a problem, just that it could be a problem, especially on deceleration when vacuum is high.

[Papa]

OK, I'm going to ask the dumb question then, "if they ARE dimpled and suppose to be tight, why are they tack welded"? I'm not saying that this is a problem, just that it could be a problem, especially on deceleration when vacuum is high.

Yep -- It's on my list of things to try to eliminate as possible causes.

Dave

[Papa]

GP Headers assures me that the headers are okay. I checked the header bolts (Stage-8 locking) and all are good with no movement. I may pull the locking tabs this weekend and re-tighten anyway as after several heat cycles, the gaskets could have compressed a bit. Many thanks to bobl and weendoggy for offering to help me learn the ropes. I still haven't made any adjustments on the car, but have been studying the data log I captured earlier in the week. As I mentioned in an earlier post, there has been some discussion about Minimum Injector Opening Time (MIOT) that I find interesting on the Holley Sniper forum. I continue to look at the correlation of my Injector Pulse Width and the AFR spikes and found that in the Sniper software if I set the display axis limits for each that I can easily see the correlation of the AFR to the MIOT value that I'm contemplating adjusting.

https://thefactoryfiveforum.com/attachment.php?attachmentid=127923&d=1588946800

In the plot, I set the injector PW axis max to my proposed MIOT value of 1.65 msec and then set the minimum AFR axis value to 16 to filter out the "normal" values. As you can see, the injector PW definitely correlates to the AFR spikes in most cases. There are a few short blips of injector PW below the 1.65 value where the AFR is below 16. If I do change the MIOT value to 1.65, there is potential to be a bit rich in the areas where the AFR is in a more normal range, but the periods are pretty short and I think I can tolerate a little more fuel better than the lean conditions that I'm trying to cure.

Anyone have any thoughts on my approach?

[Geoff H]

You are miles ahead of me with your understanding. As bobl mentioned, I played with the PW a bit but ended going back to the factory setting. The truth is the more I messed with it the worse it got. The base tune that I saved was a life saver for me.

I run the dual sync which really helps for tuning. With Bob's expertise we adjusted the timing table. Drove that for a bit, then did a few datalogs to look closer at the AFR table. We made a few changes in set rpm ranges where it was going lean - I am not going to use the correct terminology, but essentially we changed the range (decreased) the computer could adjust for the AFR within a given rpm.

I have taken it from Alberta (plains) to Yellowstone at 9,000 feet. Ran great the whole way.

Good luck!
Geoff

[Geoff H]

What type of intake manifold do you have? Are you running a spacer?

Edit: sorry - read the initial post. Air gap.

I run an RPM but needed a four hole spacer to make it run smoother.

[Papa]

You are miles ahead of me with your understanding. As bobl mentioned, I played with the PW a bit but ended going back to the factory setting. The truth is the more I messed with it the worse it got. The base tune that I saved was a life saver for me.

I run the dual sync which really helps for tuning. With Bob's expertise we adjusted the timing table. Drove that for a bit, then did a few datalogs to look closer at the AFR table. We made a few changes in set rpm ranges where it was going lean - I am not going to use the correct terminology, but essentially we changed the range (decreased) the computer could adjust for the AFR within a given rpm.

I have taken it from Alberta (plains) to Yellowstone at 9,000 feet. Ran great the whole way.

Good luck!
Geoff

Well, data analysis I can do. It certainly doesn't mean I understand the root cause and this adjustment may do nothing, but it's worth a try. If I can get the popping to stop I'll be thrilled, especially if it can be fixed with a simple adjustment and not something that I have to tear into the car to fix. I hope to try this out tomorrow, so wish me luck.

Dave

[GoDadGo]

Papa Dave,

We All Wish You Luck!

Steve

[nick7405]

Goodluck, I've been following closely.

[Papa]

Test #1 - Fail!

With the MIOT setting at 1.65 msec, The car didn't want to idle smoothly and died on me. After a restart, it seemed to settle down and I headed out of the driveway. It seemed to solve the issue at first as I didn't get any of the popping on my initial downhill coast. However, the car wasn't up to full temp and as it warmed up it started to stumble and bog down at lower rpm to the point that it wouldn't run. I was able to get it to run with the rpms up, but that wasn't going to work for normal driving. I swapped the old tune in and it ran fine as I was used to.

[nick7405]

Where did you purchase your sniper?

Depending on where it was purchased, some of the retailers give free efi tuning support of you purchased it from them.

[Papa]

Where did you purchase your sniper?

Depending on where it was purchased, some of the retailers give free efi tuning support of you purchased it from them.

The Sniper was provided by BluePrint Engines, so not a local retailer as an aftermarket add on. I've talked to a tuner in my area that could do the work, but I'd rather spend some time trying to figure it out first.

[nick7405]

Understand, I just purchased my motor from BluePrint.

[Papa]

Making progress! Weendoggy sent me a tune file that he wanted me to try and it definitely made a difference. The decel popping is gone!!! His tune still had the MIOT parameter set to 1.65 msec, but the car actually ran with whatever the other changes were in the file. I'm waiting to hear back what he did. I felt a little bit of a stumble/hestitation getting back into the throttle a couple of times (not in the datalog), but I think that may just require some additional learning as my last drive I didn't notice it.

https://thefactoryfiveforum.com/attachment.php?attachmentid=127995&d=1589070194

[bobl]

Please send me a copy of that data log and tune file that he did for you. I'd like to study it. Sorry I haven't had time to look any deeper into things, I've had 2 engines on the dyno, tuning the efi all week. Finally finished them today. So I have some time.

[sread]

Does the Holley system have a setting for "fuel cut"? The Megasquirt I used to have had a provision to completely cut fuel during coast down which should alleviate popping in the exhaust but you had to be careful not to bring it in too soon as it would cause the car to buck or jerk at certain times.

[Papa]

Bob,

Files are on the way. Don't let me interfere with work! I appreciate any time you can share. I think all weedoggy did was clear the old learn table and set all the closed loop and learn values to 100% from 50% where my starting point was.

Dave

[Papa]

Does the Holley system have a setting for "fuel cut"? The Megasquirt I used to have had a provision to completely cut fuel during coast down which should alleviate popping in the exhaust but you had to be careful not to bring it in too soon as it would cause the car to buck or jerk at certain times.

There is a setting in the Sniper to cut fuel on decel, but there are mixed reviews on getting it to work. From what I've read on the Sniper forum, it only activates above 3000 rpm, and that value isn't configurable.

https://thefactoryfiveforum.com/attachment.php?attachmentid=127749&d=1588619976

[Papa]

Here is what the learn table looked like after ~15 minutes with weendoggy's config yesterday:

https://thefactoryfiveforum.com/attachment.php?attachmentid=128019&d=1589117810

Compare that with the learn table that was there since the beginning:

https://thefactoryfiveforum.com/attachment.php?attachmentid=127747&d=1588619960

If you've followed my build, you'll recall that my car has experienced some rough patches with fouled plugs and running hyper rich, so the learn table that was in the Sniper before starting this exercise included data from all those "bad" events.

[Papa]

After essentially getting back to square one and letting the Sniper start to relearn what it wants based on the default tune, we are going to start addressing one thing at a time. We're starting with the area that was doing the popping on decel (coast). As I mentioned above, after resetting the learn table, the car was better. Now we can focus on the AFR for those points without all the accumulated issues that my old learn table had in it. To start, we isolated the vacuum (kPa) and rpm range that I can easily replicate as I leave my home and coast down a long hill. We decided to try to increase the values for this vacuum/rpm range in the Target A/F Ratio table and see how the car responds.

Here is the Before table:

https://thefactoryfiveforum.com/attachment.php?attachmentid=128255&d=1589310640

Here is the After table:

https://thefactoryfiveforum.com/attachment.php?attachmentid=128254&d=1589310631

The goal of this change is to lean the specific area of the learn table shown here:

https://thefactoryfiveforum.com/attachment.php?attachmentid=128256&d=1589310880

[Papa]

Hey guys! I haven't given up on this. I'm recovering from a surgery and can't work on the car right now, but will pick this up again in a week or so if all continues to go well with my recovery. I will say that adjusting the area in my previous post didn't produce the results I was hoping for. I did capture a short datalog that likely explains why, however. I had adjusted the 1000-1750 rpm range and as you can see in the data capture, the high AFR condition I can easily replicate that I'm associating with the popping when coasting down the hill just down the road from my driveway was produced at ~2000-2500 rpm, right after shifting into 3rd gear and the manifold pressure is at it's lowest (highest vacuum) in the 20-30 kPa range.

https://thefactoryfiveforum.com/attachment.php?attachmentid=128655&d=1589989409

Data log and config file for this post are attached.

[Papa]

Today I decided to tackle this issue from a different angle. As I had mentioned at the beginning of this thread, the car was running pretty well with the exception of the popping that I want to clear up. So, I reverted to the tune I saved from the ECU before I started with any of this. First, I let the car warm up and then did a short drive to see where it was and as it should be, it was back to what I was used to. Next, I transferred the learn table to the base and went for another drive where the car continued to feel pretty good, but still popping on coast. I then started to add fuel in the areas of the base table where the popping was most prevalent and opened the learn parameters to 100% across the board. This time, the car was better with less popping, so one more tweak to add another small amount of fuel in a very small region of the base table, and it is even better. I'm going to drive it for a while now to let it learn some more and see how it does.

[GoDadGo]

Papa Dave,

I applaud your persistence to Outwit The Sniper; however, the more I see the trouble folks have with them is likely going to keep me in The Carburetion Zone.
Also, I know you'll figure it out but remember that a lot of popping occurs when the air is rushing back into the pipes.
I remember guys causing this issue way back in the day when my hair wasn't gray when they would install Trans Am Tips on their hot rods.
That expansion of the exhaust combined with new tip would to let in just enough air in to cause some popping conditions with only that one little change.

My Question Are:
1. How Is The Car Running?
2. Is The Popping Causing Any Stumbling?
3. Could A Fresh Set Of Plugs Be Worth Installing?
4. Is the Engine Passing Unspent Fuel To The Pipes Because A Plug Is Fouled?

Good Luck & Please Keep Us Posted!

Steve

[Papa]

Steve,

The open flowing exhaust may ultimately be what's contributing the most to the popping I'm getting. Other than the popping and higher than desired idle right now, the car is running great. It starts right up and idles with no fuss. I have no stumble, hesitation, misses, smoke, or any other drivability issues. To me, the effort to learn to tune the EFI is no different than if I had installed a carb and wanted to learn how to tune that. The difference is that with the EFI, I can see what is happening and with a carb I'd need to learn to feel and listen for those subtle changes that let a pro dial in the "perfect" tune. With EFI, once I get it where I want it, it's more likely to stay that way than a carb since the EFI is making 1000 tiny adjustments/second to keep the air/fuel ratio in the target range as conditions change and a carb's tune is essentially good only for the specific conditions at the time the last adjustment was made.

After doing a lot of reading on the Holly Sniper EFI forum and discussing with a couple of guys there, the popping can be caused by a number of conditions. One, which we already discussed, is a free flowing exhaust. Others could be running too rich or too lean. When I started chasing this, I made an assumption the car was running too rich and was letting unburnt fuel into the pipes. We tried to lean it out by modifying the AFR target map and that exacerbated the popping. So, I decided to go the other direction and richen the mixture in the small areas of the fuel table where the popping occurred and it's improving. This makes sense to me because I could stop the popping at any instant by just giving the throttle a little squeeze. Of course, there is a point where too much fuel would start causing other issues, so I'm taking it slow and will see what happens as the learn table repopulates with the new base fuel settings. The awesome thing is, every time I change something, I can save that tune. Likewise, I can easily get back to any known starting point in a few seconds by loading the proper tune back into the ECU.

Dave

[GoDadGo]

I wonder if adding a pair of Exhaust Cones at the exit point of the side pipes could stop the pop?

https://www.summitracing.com/search/brand/summit-racing/product-line/summit-racing-exhaust-insert-cones/part-type/exhaust-inserts?fr=part-type&autoview=SKU&ibanner=SREPD5

I had a Meanstreak 1600 for over a dozen years (2005 Model) and changed the exhaust to a two into one set up.
With the Exhaust Cone in place I'd get minimal popping, but pull the sucker out and it would pop away.
The bike ran fine either way, but I kept the cone baffle in because of the popping.

Hummmmm?????

Steve

[Papa]

I wonder if adding a pair of Exhaust Cones at the exit point of the side pipes could stop the pop?

https://www.summitracing.com/search/brand/summit-racing/product-line/summit-racing-exhaust-insert-cones/part-type/exhaust-inserts?fr=part-type&autoview=SKU&ibanner=SREPD5

I had a Meanstreak 1600 for over a dozen years (2005 Model) and changed the exhaust to a two into one set up.
With the Exhaust Cone in place I'd get minimal popping, but pull the sucker out and it would pop away.
The bike ran fine either way, but I kept the cone baffle in because of the popping.

Hummmmm?????

Steve

Steve,

That might be an option if I can't tune the popping out. I'm really only trying to eliminate the popping under coast. I can live with the popping on down shifts. Evidently, some guys try to tune their cars to induce the popping. To each his own I guess.

Dave

[Papa]

I got the car out today and drove it about 50 miles in mixed driving conditions and it is definitely better than it was before I started bumping up the fuel in the "popping" areas. I'll pull the tune off the ECU later and see what the learn table is looking like after today's drive. I didn't do any data logging today. I feel like I'm definitely headed in the right direction now.

[BadAsp427]

Wow Dave, I just read through this... I have a headache... I'll be curious to see what your MPG ends up being. With mine, same engine, with the Holley Carb, I've been very consistent at 17mpg over the past 10,000 miles. I would think once you get all the tuning done, you'll be up over that. I'm so glad I have the carb... :-)

[GoDadGo]

I got the car out today and drove it about 50 miles in mixed driving conditions and it is definitely better than it was before I started bumping up the fuel in the "popping" areas. I'll pull the tune off the ECU later and see what the learn table is looking like after today's drive. I didn't do any data logging today. I feel like I'm definitely headed in the right direction now.

You've got the Patience & Determination of Saint!

[TMartinLVNV]

In my Forte 347 with the Holley Sniper FI, the thermostat is 180 degrees and I think the fan is set to come on at 180-185. This means that the fan is always going to be running when the thermostat is open. Even on the highway. Is there an issue with this? I'm wondering if I should bump up the Sniper fan on trigger temperature to 195 or so. That way the fan can cycle on only when needed.

What are the thoughts of people who are way more knowledgeable than me about this?

[Papa]

My fan is set to come on at 190 and off at 180.

[TMartinLVNV]

My fan is set to come on at 190 and off at 180.

When driving, is your fan only on when stopped or at low speeds at that setting?

[Papa]

When driving, is your fan only on when stopped or at low speeds at that setting?

Honestly, I can't hear it when driving the car unless I'm in town and stop & go situations in traffic. I keep my eye on the temp gauge and it does get up close to 200* in those situations, but drops right back down when the car is moving. It doesn't get as hot here as it does in Vegas.

[TMartinLVNV]

Ok, I'll give your setting a try and see how it works. Once DMV opens :mad:

Thanks

[Dagwoods]

Just came across this thread, great stuff. A little behind you at only 500 miles, but with similar issues of popping while decelerating (thought it was normal tbh). I've been trying to do some smoothing of the learn table but haven't noticed much difference. Overall, I feel like it's running strong, but I guess I don't know what what I may be missing.

You mentioned your idle is high? Do you mean it's idling high compared to what you've set your sniper idle at? Or just in general want to bring it down without it dying? I initially set my idle at 950, but it was actually idling at 1100 until I adjusted the idle screw until it read true. Since then I've backed it down to 875 which is about as low as I think I can go with my setup. Pretty lopey at that rpm.

I'm running a 427w with a pretty aggressive cam, sniper efi with full sniper ignition system and gp headers. Looking to get it Dyno tuned next weekend. Would like to grab a before and after of my tune to see what actually is changed.

[Papa]

My idle is right where I set it at 950rpm. I'd like to get it down around 800 if possible, but had issues with it when I originally had it lower. I've been able to clean up most of the popping by adjusting the base fuel table in the map/rpm region that the condition occurred in. I originally tried to lean it up by manipulating the target AFR table, but that didn't help. I spoke with one of the guys on the Holley forum who suggested I add fuel via the base table. That has made a big difference.

Let me know if you get the results you are hoping for with the tuner. I have one here that I can go to if I need to. One of the guys on the Holley forum has offered to do a remote tune, but I'd rather go with the local guy.

[weendoggy]

My idle is right where I set it at 950rpm. I'd like to get it down around 800 if possible, but had issues with it when I originally had it lower. I've been able to clean up most of the popping by adjusting the base fuel table in the map/rpm region that the condition occurred in. I originally tried to lean it up my manipulating the target AFR table, but that didn't help. I spoke with one of the guys on the Holley forum tha suggested I add fuel via the base table. That has made a big difference.

Let me know if you get the results you are hoping for with the tuner. I have one here that I can go to if I need to. One of the guys on the Holley forum has offered to do a remote tune, but I'd rather go with the local guy.

Dave,
You do have to look at both tables. Changing the AF is o.k. if the Base Fuel is close. If the BF is at 5 say, and you try to lean it out, it may be lean already and therefore taking more fuel away to meet your AF ratio. It's a trial and error when doing the tune by yourself as I said before. Easier with two people with one tuning and one driving of course, or the dyno. However, glad you're on your way. ;)

[BadAsp427]

My idle is right where I set it at 950rpm. I'd like to get it down around 800 if possible, but had issues with it when I originally had it lower.


Dave, is the desire for 800 due to the EFI? I have the same engine and have my idle set at 650 and it seems to work great there for me.. But, I'm carbed...

[Papa]

Dave, is the desire for 800 due to the EFI? I have the same engine and have my idle set at 650 and it seems to work great there for me.. But, I'm carbed...

The EFI doesn't like that low of an idle. I started at around 650 rpm and after recommendations from others, bumped it up and it is much better. Now that the car is actually being driven, I think I can bring it down a bit.

[Papa]

Dave,
You do have to look at both tables. Changing the AF is o.k. if the Base Fuel is close. If the BF is at 5 say, and you try to lean it out, it may be lean already and therefore taking more fuel away to meet your AF ratio. It's a trial and error when doing the tune by yourself as I said before. Easier with two people with one tuning and one driving of course, or the dyno. However, glad you're on your way. ;)

Thanks weendoggy -- I know these tables all interact and it takes time. I suspect that adding fuel as I have may only address a symptom and not a cause, so I'm happy to keep tinkering as long as the car continues to run well. I may still just take it to a professional with a dyno and let them dial it in correctly. What are your thoughts on being able to drive at very high altitudes with the Sniper? Should I think about a separate tune for those conditions above 10-11,000 feet?

Dave

[weendoggy]

Thanks weendoggy -- I know these tables all interact and it takes time. I suspect that adding fuel as I have may only address a symptom and not a cause, so I'm happy to keep tinkering as long as the car continues to run well. I may still just take it to a professional with a dyno and let them dial it in correctly. What are your thoughts on being able to drive at very high altitudes with the Sniper? Should I think about a separate tune for those conditions above 10-11,000 feet?

Dave

If you keep in mind you're main driving is where you live at the 6K' altitude, setting it to run there is fine. I wouldn't worry too much if you just take occasional trips to the 10K' level. It may run a little boggy (less air), but it will run fine. If you find yourself taking more trips to that area, a 2D table to allow the change would be helpful. You'll find the same problem (more air) when you go to below 1K' as well, the same issue will rise up. Keeping the same AF is good and not the issue, the Base Fuel will need to be set. Air is the big culprit with it being less dense the higher and more dense the lower you go. Thus, the Base Fuel will need pampering every time, but for your occasional trips to these areas, unless you really want to setup tables, I'd leave it be once you dial into your main driving area. I live at sea level and my occasional trips to the Sierra's do pose some issues, but not enough for me warranting a change. If I did a lot of trips, I'd make a 2D table to adjust BF based on MAP settings. I would get it tuned well for your normal driving area and see how things go. If you need to change, or want to change, I'd do it after you have it tuned well. I don't think going to a dyno is really needed, but if that's what makes you comfortable, I'd go ahead. It won't hurt.

Glenn

[Papa]

If you keep in mind you're main driving is where you live at the 6K' altitude, setting it to run there is fine. I wouldn't worry too much if you just take occasional trips to the 10K' level. It may run a little boggy (less air), but it will run fine. If you find yourself taking more trips to that area, a 2D table to allow the change would be helpful. You'll find the same problem (more air) when you go to below 1K' as well, the same issue will rise up. Keeping the same AF is good and not the issue, the Base Fuel will need to be set. Air is the big culprit with it being less dense the higher and more dense the lower you go. Thus, the Base Fuel will need pampering every time, but for your occasional trips to these areas, unless you really want to setup tables, I'd leave it be once you dial into your main driving area. I live at sea level and my occasional trips to the Sierra's do pose some issues, but not enough for me warranting a change. If I did a lot of trips, I'd make a 2D table to adjust BF based on MAP settings. I would get it tuned well for your normal driving area and see how things go. If you need to change, or want to change, I'd do it after you have it tuned well. I don't think going to a dyno is really needed, but if that's what makes you comfortable, I'd go ahead. It won't hurt.

Glenn

Thanks, Glenn. I think I'd like to start experimenting with the idle speed next. Do I just get the car to operating temperature, adjust the setting in the ECU and then dial the idle screw to the desired setting?

Dave

[weendoggy]

Thanks, Glenn. I think I'd like to start experimenting with the idle speed next. Do I just get the car to operating temperature, adjust the setting in the ECU and then dial the idle screw to the desired setting?

Dave

Yes. Engine operating temperature. I doubt you'll be able to have that idle below 850rpm with good results. Depending on how radical your cam is, it may not like it. My Terminator runs at 850rpm +/- and has a nice lope. Any lower and it's a pig. I'd try that area nd set the ECU to confirm this is what you want.

You should run in Open Loop and tune the idle off the BF table (lbs/hr). Highlight a large block, maybe 20 or so, around the "football" (with it in the center of the cells) and then using your Up/Down arrows with the Ctrl key pressed, move the BF range up until the engine doesn't like it (note reading), then down until the engine doesn't like it (note reading) and then balance in between those readings. Ex: up and chokes out at 10, down and chokes out at 5, which would mean it likes a 7.5 area in the idle range. Now, this can be subjective, but gives you an idea on what to do. When doing the testing, move the arrow keys and wait a bit before moving again so you give the system some time in that area. 10-15 secs is good. Once you and the engine are happy, put the ECU back to closed loop. Save your file and just clear the Learn table and go for a drive. You can compare the new/old file to see what happened. Just save the new one different.

Glenn

[Papa]

Yes. Engine operating temperature. I doubt you'll be able to have that idle below 850rpm with good results. Depending on how radical your cam is, it may not like it. My Terminator runs at 850rpm +/- and has a nice lope. Any lower and it's a pig. I'd try that area nd set the ECU to confirm this is what you want.

You should run in Open Loop and tune the idle off the BF table (lbs/hr). Highlight a large block, maybe 20 or so, around the "football" (with it in the center of the cells) and then using your Up/Down arrows with the Ctrl key pressed, move the BF range up until the engine doesn't like it (note reading), then down until the engine doesn't like it (note reading) and then balance in between those readings. Ex: up and chokes out at 10, down and chokes out at 5, which would mean it likes a 7.5 area in the idle range. Now, this can be subjective, but gives you an idea on what to do. When doing the testing, move the arrow keys and wait a bit before moving again so you give the system some time in that area. 10-15 secs is good. Once you and the engine are happy, put the ECU back to closed loop. Save your file and just clear the Learn table and go for a drive. You can compare the new/old file to see what happened. Just save the new one different.

Glenn

850 would be a lot better than the 950 I'm at now. My cam isn't too crazy, but will lope a bit at low idle speeds. I'd started at ~700 with the initial setup that BPE used (FAST XFI Street), but that didn't work well and I was fouling plugs.


https://www.youtube.com/watch?v=doBle7rb7hI

When I initially set up the Holley, I was told to start with a higher idle, which is where the current 950 value was established.

[bobl]

weendoggy, You mention using a 2D table to correct for altitude changes. With my Holley HP ecu I was able to build a 2D table using BARO(barometer) parameter and alter timing, fuel, cranking fuel, etc. based on the actual reading, which solves the problem for altitude changes . However the Sniper does not have that parameter in the advanced tables or in the data log parameters. Apparently they didn't see a need to look at the absolute barometric pressure with the Sniper. I've not pursued any further though. Have you had any success doing this with the Sniper?

Bob

[Papa]

I adjusted the idle down to 850 rpm and drove the car into town with some stop & go traffic and it seems happy and sounds better than the higher idle at 950 rpm.

[Papa]

I got to take the car on a real drive, 270+ miles yesterday and I'm very pleased with the way the EFI performed. Listen to the first minute of this video and notice what you don't hear!


https://youtu.be/Ay8SRyLU6cY

[bobl]

Sure didn't hear any popping, then the music started and I fell asleep... LOL That is certainly relaxing. The car sounds good. So, what was the final resolution(s)?

[Papa]

Sure didn't hear any popping, then the music started and I fell asleep... LOL That is certainly relaxing. The car sounds good. So, what was the final resolution(s)?

Hey Bob,

What I ended up doing per a recommendation from a guy on the Holley Forum was to start to add fuel in the RPM/MAP regions where I was getting the popping on decal. It was only a few cells of the base table that I adjusted a little at a time. Under certain higher RPM conditions, I'll still get some popping when down shifting, but not just under coasting conditions. I can live with that. Before making any adjustments, I went back to the tune that was first downloaded where the car was running good except for the popping. I cleared the learn table and adjusted the fuel up by 10% in the trouble areas and set the learn parameters to 100%. I then drove the car for about 20 minutes and merged the new learn table with the base. After about three iterations of this, I was happy with the way it was behaving and reduced the learn parameters down to 50% and have been running with that for about 400 miles now. I also dropped the idle down from 950 to 850 and like the way that is doing as well.

I know it isn't perfect, but it's so much better now that I think I'll leave it alone for a while. I'm still thinking about getting it to a professional tuner at some point.

Thanks to both you and Glenn and the guys over on the Holley forum for all the advice and your time helping me with this.

Dave

[GoDadGo]

Hey Papa Dave,

Your Engineering Patience Is Showing!
By the time you're done, I'm sure you'll be the guy every Sniper fan is reaching out to on this forum.
On a related note, we had a gentleman from COBB Tuning give a presentation on their programming tools at the PCA meeting last night.
It was extremely interesting, though 100% NOT applicable to my ride, but I enjoyed the event immensely.
Glad You're Making So Much Progress With Your Snyper System Because I Know You'll Be Sharing Your New Found Knowledge!

Steve

[Megascott]

I know some ricers that purposely lean out the bins in the lower map decel regions just to get it to pop like that. Personally I don't like that feature, so what you are doing by increasing VE (Richer) in those bottom bins is the right thing. I've not tuned many Holley Efi cars, mostly Megasquirt, but the theory is the same. What I would do is save your tune, then choose all those lower bins and increase the bottom two or three rows by 10% or so until it goes away on decel. Scott

[TMartinLVNV]

I'm just starting to read up on all of the adjustments for the Sniper. My motor is running very well after I got the IAC adjusted correctly. I have almost 1000 miles on it. I hooked up the display controller and keyed on. The TPS reads 0% as it should. I depressed the pedal all the way to the floor and could only get 78% throttle. I then opened the throttle blades manually on the side of the throttle body and can get 79%. So I think that I have the pedal and cable adjusted correctly. In reading the Holley literature, I should be able to get 95-100% throttle at WOT.

What readings do you get at WOT? I'm thinking about calling Holley tomorrow morning to see if I can do anything else.

Also, my idle is right at 850-900. I was trying to lower it down to 750 or so as recommended by Forte's FI guy and my cam (Ford E cam). I started at 800, then 700 target idle speed but it does not change the idle down at all. When I turn in the idle screw, the motor starts to stumble when letting off of the throttle and the motor is cold (my original problem that I fixed by adjusting the same screw).

[Papa]

I'm just starting to read up on all of the adjustments for the Sniper. My motor is running very well after I got the IAC adjusted correctly. I have almost 1000 miles on it. I hooked up the display controller and keyed on. The TPS reads 0% as it should. I depressed the pedal all the way to the floor and could only get 78% throttle. I then opened the throttle blades manually on the side of the throttle body and can get 79%. So I think that I have the pedal and cable adjusted correctly. In reading the Holley literature, I should be able to get 95-100% throttle at WOT.

What readings do you get at WOT? I'm thinking about calling Holley tomorrow morning to see if I can do anything else.

Also, my idle is right at 850-900. I was trying to lower it down to 750 or so as recommended by Forte's FI guy and my cam (Ford E cam). I started at 800, then 700 target idle speed but it does not change the idle down at all. When I turn in the idle screw, the motor starts to stumble when letting off of the throttle and the motor is cold (my original problem that I fixed by adjusting the same screw).

My TPS reads from 0% to 98% closed to WOT. My idle was at 950 and I dropped it to 850 and it still runs good and no issues with stumbling as I come to a stop. Lower than 850 probably isn't realistic for the Sniper based on everything I've read. To set the idle, first set your target in the handheld to what you want it to be. Then:

IDLE SETTING/THROTTLE PLATE SETTING
Once the engine is up to operating temperature (above 160° F), the idle speed can be set to what was configured in the Wizard.
To do this, open up the Initial Startup gauge screen. With the vehicle in neutral, adjust the idle screw until the IAC Position
reads between 2% and 10%. While adjusting the throttle plate screw, watch the TPS value and make sure it stays at 0%. While
adjusting the throttle plate screw, the TPS position may begin to read higher than 0%. If this happens cycling the ignition switch
will recalibrate the TPS back to zero.
NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160°F!

[TMartinLVNV]

I'm just starting to read up on all of the adjustments for the Sniper. My motor is running very well after I got the IAC adjusted correctly. I have almost 1000 miles on it. I hooked up the display controller and keyed on. The TPS reads 0% as it should. I depressed the pedal all the way to the floor and could only get 78% throttle. I then opened the throttle blades manually on the side of the throttle body and can get 79%. So I think that I have the pedal and cable adjusted correctly. In reading the Holley literature, I should be able to get 95-100% throttle at WOT.

What readings do you get at WOT? I'm thinking about calling Holley tomorrow morning to see if I can do anything else.

Also, my idle is right at 850-900. I was trying to lower it down to 750 or so as recommended by Forte's FI guy and my cam (Ford E cam). I started at 800, then 700 target idle speed but it does not change the idle down at all. When I turn in the idle screw, the motor starts to stumble when letting off of the throttle and the motor is cold (my original problem that I fixed by adjusting the same screw).

I fixed the 78% max TPS problem. There was an interference problem on the throttle linkage with my cruise control hookup.

https://thefactoryfiveforum.com/showthread.php?33080-Terry-in-Las-Vegas-Build-1000-miles!-almost&p=423396&viewfull=1#post423396

[Caddy Dad]

I just got my Mk IV with BPE 347 Holly Sniper EFI out on the road this week. She's running great. Not much popping etc when I coast down a hill. However, I do have a an issue where the RPM will almost drop to zero and then recover when I push the clutch in when coasting up to a stop. This seems to be a common occurrence with Snipers and there are multiple threads on the Holly Forum for me to research, but just wondering if you also ran into this issue? If so, how did you solve it?
Thanks!

[Papa]

I just got my Mk IV with BPE 347 Holly Sniper EFI out on the road this week. She's running great. Not much popping etc when I coast down a hill. However, I do have a an issue where the RPM will almost drop to zero and then recover when I push the clutch in when coasting up to a stop. This seems to be a common occurrence with Snipers and there are multiple threads on the Holly Forum for me to research, but just wondering if you also ran into this issue? If so, how did you solve it?
Thanks!

So, the first question I'd ask is where you set your idle? If it's below ~850-900, you are going to have trouble. I haven't done any tuning of the idle circuit other than use the quick setup to set the desired idle speed and IAC screw.

[Caddy Dad]

So, the first question I'd ask is where you set your idle? If it's below ~850-900, you are going to have trouble. I haven't done any tuning of the idle circuit other than use the quick setup to set the desired idle speed and IAC screw.

I haven't adjusted the stock parameters that came with the engine when it was delivered. So the idle is set about 1000 RPM and I haven't touched the IAC screw. From what little I've read I'm thinking that maybe the idle ramp down time may need to be adjusted?

Thanks!

[Papa]

I haven't adjusted the stock parameters that came with the engine when it was delivered. So the idle is set about 1000 RPM and I haven't touched the IAC screw. From what little I've read I'm thinking that maybe the idle ramp down time may need to be adjusted?

Thanks!

I'd recommend first simply running through the quick setup for setting the idle and see where that gets you. I'd target ~900rpm to start.

IDLE SETTING/THROTTLE PLATE SETTING
Once the engine is up to operating temperature (above 160° F), the idle speed can be set to what was configured in the Wizard.
To do this, open up the Initial Startup gauge screen. With the vehicle in neutral, adjust the idle screw until the IAC Position
reads between 2% and 10%. While adjusting the throttle plate screw, watch the TPS value and make sure it stays at 0%. While
adjusting the throttle plate screw, the TPS position may begin to read higher than 0%. If this happens cycling the ignition switch
will recalibrate the TPS back to zero.
NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160°F!

[TMartinLVNV]

I just got my Mk IV with BPE 347 Holly Sniper EFI out on the road this week. She's running great. Not much popping etc when I coast down a hill. However, I do have a an issue where the RPM will almost drop to zero and then recover when I push the clutch in when coasting up to a stop. This seems to be a common occurrence with Snipers and there are multiple threads on the Holly Forum for me to research, but just wondering if you also ran into this issue? If so, how did you solve it?
Thanks!

I had this exact problem. I now have my desired idle speed set at 800 and set the IAC exactly according to Dave/Holley's instructions. My issue was that the IAC was set too closed and I needed to open it up a smidge. Make sure that you fiddle with it set up the way to plan to drive on the street. What messed me up was that I originally set it up without the air cleaner on. After putting the air cleaner on, a slight restriction was added and the throttle blades needed to be opened just a little to compensate. I have 3700 miles now and it runs great. I am a big fan of the Sniper. From sea level to 11,000 feet on a cold morning, the car starts right up and drives great. I average 17-19 mpg and even got 21 on an extended drive at 65 once on my 347.

[wrp]

Id like to see this as a major subforum under the root. Great information here. I just recently installed the Stealth Sniper on my 383 Chevy Stroker. I also installed the Hyperspark Distributor and control box. I had a rough start as the initial setup was off. I went to pull the Sniper System off the car and decided to take it through setup again and there were several errors in the initial tune. Once setup, the self learning took over and the system performs flawlessly. After a few weeks we dyno'd the car and picked up nearly 80 whp over the Holley self learned tune. Additionally we picked up nearly 40% more gas mileage and the operating temperature of the car dropped 5-10 degrees. Currently working on setting the two step up.

[Caddy Dad]

I'd recommend first simply running through the quick setup for setting the idle and see where that gets you. I'd target ~900rpm to start.

IDLE SETTING/THROTTLE PLATE SETTING
Once the engine is up to operating temperature (above 160° F), the idle speed can be set to what was configured in the Wizard.
To do this, open up the Initial Startup gauge screen. With the vehicle in neutral, adjust the idle screw until the IAC Position
reads between 2% and 10%. While adjusting the throttle plate screw, watch the TPS value and make sure it stays at 0%. While
adjusting the throttle plate screw, the TPS position may begin to read higher than 0%. If this happens cycling the ignition switch
will recalibrate the TPS back to zero.
NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160°F!

Hi Papa,
I was finally able to get around to adjusting the IAC as you have described. I first checked the idle setting via the handheld. It was set to 800 so I bumped it up to 900 and enabled it by cycling the ignition. I started her up and let her warm up and go through a couple of cycles of the turning the cooling fan on (190) and off (180). The handheld was indicating the IAC was at 9 and TPS 0. So I adjusted it anyway up and down to get the IAC close to 6. I found out it doesn't take much, maybe a 1/4 to 1/2 of a turn to go from 2 to 10 on the IAC. The TPS bumped up to 1 so I cycled the ignition again to reset it to 0. I then took her for an initial test drive and it's much better, but not perfect. The RPMs will drop when I coast to a stop but not as low as before. Should I increase or decrease the IAC? I'm guessing decrease it to 2-4 and try again?

What about idle ramp down? I'm guessing that's its best to get IAC dialed in first then worry about idle ramp down?

Thanks for all your help!

[Papa]

Here are my IAC settings:

https://thefactoryfiveforum.com/attachment.php?attachmentid=137081&d=1604356031

I haven't modified them at all from the base tune. The only time my car has acted like it wanted to die was during a fairly abrupt stop where I basically clutched and mashed on the brake pedal to stop at a light. I typically have the RPMs down pretty low as I bring the car to a stop and don't have any issues.

Here are a couple of threads on the issue over on the Sniper forums:

https://forums.holley.com/showthread.php?20351-Idle-Settings-To-Prevent-Undershoot/page2
https://forums.holley.com/showthread.php?47754-Stumbling-amp-stalling-when-slowing-to-a-stop

This stood out to me from the second thread:


Ensure the idle speed screw on throttle body, is adjusted to achieve an IAC Position of about 5% at hot idle.
In the Idle ICF, the "Target Idle Speed (RPM)" must be programmed to the desired RPM speed at hot idle.
Ensure the fuel injectors or spark plug wires (or any other high voltage wiring) aren't too close to the IAC motor/wiring.
The IAC motor is easily susceptible to electrical interference, and it'll cause strange occurrences and become inoperable.


Dave

[Papa]

Some useful links from Holley:

Software: https://documents.holley.com/techlibrary_sniper1.2.17installer.zip

How-To Videos: https://www.holley.com/support/fuel_injection/sniper_efi/

Sniper Forum: https://forums.holley.com/forumdisplay.php?82-Sniper-EFI

[RRussellTx]

Very helpful thread!

I have some input from my experience and a question about spark plugs.

My experience,
I have a 427w from Forte with a Terminator EFI. I have always had an issue at low speeds with rough running and bucking as well as a rich smell at idle. I replaced the intake with a lower RPM intake and that helped a bit but it did not solve the issue. Also, I recently replaced the handheld as it had faded and they no longer support that version. During this process, I also upgraded all of the firmware on the Terminator ECU and reset the baseline to see if I could start from scratch and get better results.

After struggling with the base learning and before I started to begin the process of following the steps in this thread, I thought I would address the spark plugs. I was afraid they might be suffering from all of the bad instructions so I pulled out the Autolite 3923 plugs and they did indeed look like they had been running VERY rich. They were all gapped to about .031. I decided to replace them with the Autolite Platinum 3923 which were factory gapped at about .040. I decided to leave it at .040 because Forte had the gap much lower and the quick research I did was more in the .044 range. The .040 seemed a reasonable place to start.

I just got back from a 10 minute drive and the difference is amazing. The only thing I did was change the spark plugs and the low speed bucking is 100% gone. The super rich smell at idle is gone. Seems to be a huge improvement and I'm just getting started. The issue that I still have is that is dies on occasion when I am decelerating with the clutch in. Not cool with power steering. I'm hoping more learning with good plugs and some of the tips in this thread will get me there.

My question,
What is the right Spark Plug/Gap? Is the factory .040 about right or is there better way to figure it out?

Thanks!