poor idle and running rich

[Joel Hauser]

It's been almost 9 months since I got my roadster registered and on the road, but I'm having a heck of a time figuring out why it runs so rich, and idle's so ... lousy. The motor operates fine at driving speed and temperatures, and seems very powerful to me. but once it warms up, the idle drops so low that the car stalls. this is obviously a problem when driving when coming to a stop or slowing into a sharp turn.

I know this isn't a factory five problem, but do you guys have any ideas what is causing this performance issue. I used a 1996 donor car with a the original EFI and ECU from the mustang. I had the the block round bored and rebuilt the block to pretty much stock specs. I'm using the original ford intake manifold, throttle body and plenum. I'm using the FF/hooker headers without cats. No egr. The gas tank is new, as is the gas filter.

So far, this is what I've done trying to fix the idle and rich mixture.
New idle air control valve
new fuel pressure regulator
new upstream 02 sensors
new coolant temp sensor
checked for vacuum leaks but haven't found any.
checked for continuity breaks between all the sensors, but haven't found any

I purchased a BAMA/SCT tuner from American Muscle. BAMA installed a tune which is supposed to take into consideration the EGR delete, cold air intake, side pipes and no cats, but it made no difference. BAMA has asked me to send them a data log so they can review the ECU performance, but I haven't done it yet; I live in the Albany NY area, and it's just been too cold to work on the car outside.

There aren't any shops within 60 miles of here that seem interested or able to do a custom tune.

Thanks for any suggestions.

81200

[Big Blocker]

What engine? Not that familiar with '96 but earlier 5.0's had stuff that caused drive-ability issues if certain items weren't addressed.
Have you by-passed all the smog related items in the factory harness or EEC? (EGR, TAB/TAD, carbon canister solenoid) Are you running the Speed sensor (VSS) to the EEC?
The idle air control (IAC) is, to the best of my knowledge, for cold starting times only and does not control air flow once the engine comes up to temp. It's part of a fuel enrichment circuit (think: carb'd car with a choke).

Hopefully other guys will jump in here with more know-how on the later EFI.

Doc

[Joel Hauser]

Thanks Big Blocker.
My engine is the 4.6L SOHC from a 1996 GT.
I didn't install the carbon canister; I threw it away. Oops. When I purchased the tune from BAMA/American Muscle I told them about the EGR delete, headers and sidepipes, cold air intake, and no cat. I didn't mention the carbon canister. Also, I was looking at the engine this morning - isn't that what we all do on a Sunday morning? - and saw that the injectors are F1SE-E5A ford red injectors, which according to many on the blogosphere are 30lb injectors. Maybe these aren't the original stock injectors? The guy I bought the mustang from didn't drive the car; it didn't work when I bought it; it had a blown head gasket and one cylinder was badly scored up. He said he took it in trade from the previous owners who had been drag racing it, and had tuned it for that. Maybe they installed bigger injectors?

when I run the datalog for BAMA, I'll mention that I don't have the carbon canister, and the injectors might not be stock.
Thanks, and more suggestions and advice will be appreciated.

[Jeff Kleiner]

Sounds like it's going to hell when it warms up enough to go into closed loop. The ECU does not look at O2 before it reaches full operating temp or at WOT--- any chance you have the O2 harness swapped side to side?

Jeff

[Jeff Kleiner]

Edit/further comment: I do not know what a '96 4.6 began with but 30# sounds huge. If the ECU or MAF has not been matched to them it will be pig rich.

Jeff

[Joel Hauser]

thanks Jeff,
I'm almost certain I've got the O2 sensors wired up correctly. I originally was running without any because neither the headers or sidepipes had threaded inserts/bungs for them. I later welded in the bungs, purchased a new O2 wiring harness from Ron Francis, and new O2 sensors. I've checked continuity between the ECU harness and the sensors, and it seems good.
If my problem turns out to be with the size of the injectors, hopefully a custom tune from BAMA will fix it.
My biggest lesson learned from this was, don't buy a donor car just because it was the least expensive one you could find. I paid $2000 for mine, and ended up putting several thousand into the rebuild. But more of a headache was I purchased a car that had been stripped of countless necessary parts. I should have purchased a complete car that worked from the start. Live and learn, although at 64 years old you'd think I would have learned this a long time ago.
Thanks
Joel

[Racee75]

Hi Joel,
The #30 injectors do sound big if it is a stock engine, I had a stock 4.6 out of a 97 Mustang and they had orange injectors and I believe they are#19

[Joel Hauser]

Thanks Racee, my injectors are redish brown, not orange. I'm starting to think that my injectors may be the cause of the rich mixture...but I've said that before about a lot of things. Hopefully I can get a new tune from BAMA that will adjust for it.
Thanks everyone for your input. This forum has been very helpful.
By the way, I have a picture album on the forum, if anyone cares to see my car.
Joel

[myjones]

Thanks Racee, my injectors are redish brown, not orange. Joel

Joel
There should be some numbers on the body of the injector, they are sometimes small and hard to see but with light and magnification
you should find them.
You may have to remove a fuel rail or fully remove one injector after bleeding down the pressure but you really need to find the numbers
and look it up online.
HTH
Dale

[Arrowhead]

I think your on to something with the injectors Joel (although I thought the 19# were that reddish brown color). Like myjones said, best to check the part number. Not sure about the Mustang, but the Lincoln Mark VIII 4.6 DOHC comes with 24# injectors, the GT may have even come with 19#, not sure. Either way 30# would run real rich on a stock tune. You could either swap in the correct injectors or reprogram like you said. But, why did the original owner swap in 30# injectors? What else, if anything, did they modify? Larger throttle body? Cams? Those are other parameters they should know if you choose to re-tune.

No personal experience with these guys, but they could dyno tune for you.

http://www.twistedsynergymotorsports.com/index.html

[Joel Hauser]

Upon closer examination of the injectors I see that on one side they are marked "ford F1SE-E5A" and on the other 280 150 945. googling 280150945 I found this website https://www.fiveomotorsport.com/fuel-injectors/ford/#bluetop. Scrolling down I found my injectors, which are described as, "NEW 30LBS BOSCH FUEL INJECTORS: 30lbs/hr 330cc/min (Bosch) RED TOP, 4-hole Fuel Nozzle".
So, assuming fiveomotorsports is correct, maybe if I tell BAMA that I'm using bigger injectors, they can write a program that takes that into account, and my car will run like a top?
We'll see.
I've contacted twistedsynergy before. They told me they no longer have the software to tune 1996 mustang engines. But everyone tells me they are the go to shop in the Albany NY area.

[nskaats]

Bosch red tops are definitely not the stock injector for that engine. The stock injectors should only be 19 lb/hr. So if the tune hasn't had the correct injector data input, the new injectors are flowing almost double what the PCM thinks is in there. If you get the info sent over they should be able to at least get you a calibration that will idle. A stock engine will run perfectly fine with the 30 lb injectors if tuned correct.

I will say I've never seen a BAMA tune that was correct. Not even close at wide open throttle. We make a good living correcting their tunes and other mail orders. That being said, they should at least be able to get it driveable to where you can get it to someone that can tune it properly. I definitely wouldn't recommend doing any wide open throttle driving until it's been on a dyno and verified fuel and timing are safe. You want to make sure you have it tuned by someone who can place their hands on the car and do it right.

[Joel Hauser]

thanks Nick, I appreciate your confirmation that these are probably not the stock injectors.
As for a custom tune, there just doesn't seem to be anyone within 150 miles of Albany NY that will tune such an old 1996 car. That's why I ended up going with BAMA. I'll keep my fingers crossed that they can write a decent tune that gets the car running closer to normal. I'm not going to be racing; heck, I'll probably never go over 50 mph. I just want it to run reliably enough so my kids can take it out when they come home to visit. My wife says if you want your kids to visit, you have to give them a reason to come home. taking a cobra out for a drive seems like a good reason!
Joel

[Joecobr]

Hi Joel,

A Google search tells me the stock fuel injectors on your car are 19#. Cost aside, the best course of action is to buy a new set of 19# injectors, install them and your existing tune is probably pretty close. A new set of injectors is about $200. I believe you’ll end up spending more fiddling with a new tune for the 30# injectors and still not be satisfied. I am not an expert in this and certainly am cost conscious but that is the way I would approach it.

Joe

[Joel Hauser]

Hi Joe, good to hear from you!
You know, you're right...so I just ordered a new set of 19# injectors. I can still order a tune, and I'll hold onto the 30# injectors for future use, if I put in a bigger throttle body perhaps.
Send me some pictures of your build.
Joel

[nskaats]

thanks Nick, I appreciate your confirmation that these are probably not the stock injectors.
As for a custom tune, there just doesn't seem to be anyone within 150 miles of Albany NY that will tune such an old 1996 car. That's why I ended up going with BAMA. I'll keep my fingers crossed that they can write a decent tune that gets the car running closer to normal. I'm not going to be racing; heck, I'll probably never go over 50 mph. I just want it to run reliably enough so my kids can take it out when they come home to visit. My wife says if you want your kids to visit, you have to give them a reason to come home. taking a cobra out for a drive seems like a good reason!
Joel

From what I remember, one of their selling points is free updates so you should be able to have them update the injector data at no cost without having to buy more injectors. It's getting harder to find people that will tune the older Ford platforms as they're really not the most intelligent systems and notoriously difficult to work with. I can poke around within my groups of fellow tuners and see if anyone is in that region.

[Joel Hauser]

thanks Nick, you're right about BAMA offering free tunes for life. If you know of any tuners in my area, please let me know. Although I dropped $400 into BAMA tuner, I'm sure the car would benefit from a professional quality tune by someone who knows what he or she is doing.
Joel

[nskaats]

I put some feelers out for you. I'll let you know if I hear of anything.

[Joel Hauser]

thanks Nick
My new 19# injectors came in the mail yesterday. Hopefully I can get them installed this weekend. I'll let you know what happens.
Joel

[nskaats]

Responses I've received so far:
Wicked Motorsports - Toms River, NJ
Pops Racing - Western NY
Twisted Synergy - Rensselaer, NY
Coppola Motorsports - Malta, NY
Quantum Race Works - Selkirk
Performance Dyno - Loudon, NH

[Joel Hauser]

Nothing but discouraging news. I replaced the 30# injectors with the 19# injectors, crossed my fingers, started it up and went for a drive; it was 45 degrees out, so it was not much fun. Anyway, the car still smells like it is running just as rich as it did with the 30# injectors. The idle is still uneven, and occasionally stalled when slowing down for a stop or turn. Also the car had some hesitation on acceleration, although not all the time. It didn't do that with the larger injectors. I've got codes P1131 and P1151 which means that both banks are running lean.
So, I decided to throw more money at the problem and have ordered a new MAF sensor, and a new intake air temp sensor. I also ordered two new 02 sensors, just because I like to waste money. Maybe the previous sensors were both bad?
I still have to ask BAMA to write a new program for my ECU, but first have to run a datalog for them. It's raining and cold outside, so I won't be able to do that today.
If I can't figure this out myself, maybe I'll bring the car to the ford dealership or a mechanic who actually knows what he's doing. I expect ford will not be able to help because I removed the EGR and Cats. I've contacted the local tuning shops around Albany - the same ones Nick mentioned - but they don't seem interested. They don't return my calls or emails.
Maybe I should convert it to an electric car?

[nskaats]

Before you throw a ton of money into it, let's have a look at the spark plugs. If it was programmed for 19 lb injectors and you ran the 30s, they're likely fouled.

The other possibility to consider is the rich condition could be caused by fuel trims. If you have a vacuum leak at the intake manifold or an exhaust leak ahead of the oxygen sensors, the pcm will read a false lean condition and dump fuel to compensate. Same can happen if your exhaust is too short. If the oxygen sensors are within 18-24 inches of the exhaust exit, they'll read ambient airflow and cause the pcm to do the same thing. Especially at lower rpm.

What software do you have for datalogging? An idle log will likely tell you what you need to know as far as diagnostics.

[nskaats]

Btw, some shops do have issues returning calls in a timely manner. We're going into a busy time of year. Not that it's an acceptable reason, but it does happen. I'm currently booked out close to two months but we do try to return every call.

[Joel Hauser]

I'll check the plugs, but I expect they are fine. I cleaned them probably no more than 30 miles ago. I have checked for vacuum leaks using carb cleaner around the hoses, but nothing obvious showed up. I just built the motor, and used new gaskets all around, so I don't think there is an intake manifold leak into the heads or between the intake manifold and the throttlebody/plenum. The O2 sensors are installed in the collector at the front end of the side pipes, just after the bend where they come out from the body. The side pipes didn't have bungs on them, so I drilled holes and welded the bungs in myself. There really was no other place to put them since I used the factory five custom headers. I'm pretty sure there aren't any exhaust leaks. I've tightened up the bolts, and all the gaskets are new.
I'm going to run a data log using the BAMA tuner once the weather warms up a bit. Maybe it will reveal a fault.
Thanks again Nick for all your good advice. Keep it coming, if you think of something else.
Joel

[Jeff Kleiner]

Just as a quick experiment unplug both O2 sensors and give it a try. It won't go into closed loop and will just run on the fuel tables but that can tell you if what the ECU is seeing from the sensors is what it's trying to correct.

Jeff

[myjones]

The other thing I haven't see posted yet is the actual fuel pressure at the engine.
IF they have it dialed down to help compensate for the 30# injectors it would be too low for the 19's.
Also haven't seen whether that new regulator is vacuum indexed style or not. If it is a vacuum indexed regulator and you
just plug that port it will act erratic once it warms up. HTH
Dale

[Joel Hauser]

Just a short update. My motor is still running poorly. Because I don't know what I'm doing, I installed a new MAF sensor, new O2 sensors (just in case the first ones I installed were both bad - I know that was unlikely, but I like throwing my money away) and a new intake air temp sensor. None of this made any difference at all. My next step is to do a detailed datalog with my BAMA tuner, and let BAMA analyze it and try writing a program that fixes this mess.

How I wish I had a carburetor! This new fangled fuel injection is driving me crazy. I'm too old for this.

[nskaats]

Did you end up putting the 19 lb fuel injectors in it? It will still run like crap until you have injectors that match the data in the pcm. So you need to put the 19s in it with that tune, or get the tune changed to match those injectors.

[Joel Hauser]

Thanks Nick, Yes I put the 19# injectors in. No, I haven't gotten a new tune for the PCM yet. I tried, but it was just too cold to sit outside trying to gather a datalog for BAMA. It's still in the 20's and 30's in upstate NY, and we've gotten tons of snow in the last week. I'm hoping that once I run the datalog, submit it to BAMA, and get a new tune from them, the car will just purr. I'm going to try to stop wasting anymore money on parts that don't need to be replaced. Truth is, there's not much more to replace.
Thanks again Nick, your advice is really appreciated.
Joel

[Joel Hauser]

It's been about a month or so since my last update on my idle and running rich problems. I installed a new tune provided by BAMA, which greatly improved the air fuel mixture. It's still smells a little rich, but much less so than before the tune. That's the good news. The bad is that the car continues to stall when you let off on the gas and depress the clutch as you approach a turn or a stop. Otherwise, the car runs great.
After installing the new BAMA tune, I checked the fuel pressure. It was ridiculously low; 5 lbs. I diagnosed a problem with the fuel pump, so I bought a new pump and installed it. When I got the old pump out, I saw that it was a mess. The rubber hose that connected the pump to the supply tube that exits the tank was almost completely disconnected; I don't know how any fuel was passing through it. And the check valve which maintains pressure and prevents the fuel in the supply line from flowing back into the tank fell out of the pump. The new pump makes a huge difference. The car starts immediately, and there is no hesitation at all on acceleration.
So, I've installed a new MAF, new 02 sensors, new IAC valve, new air temp sensor, new injectors, and new pump. I have an EGR delete plate. I've check over and over for vacuum leaks, and can't find one. I'm not using a carbon canister.
I'm going to do another datalog and ask BAMA to write another tune. They've been really patient with me. Hopefully with all these new parts, they'll be able to come up with something that makes the engine run properly.
Any suggestion from the FF community are always appreciated.
Joel

[Joel Hauser]

Here is my latest update; it's not good. BAMA said that the datalog looked to them like there was a vacuum leak, so I decided there might be a crack in the old intake manifold. I did a smoke leak test and there seemed to be some leaks coming from the underside of the plastic intake manifold. It's over 20 years old, and I understand they are prone to cracking. I purchased a new one - they cost $120 on ebay - and installed it this weekend. Unfortunately, the idle and low speed performance is now worse than before. The engine runs fine at over 3500 rpm, but it won't idle at all once the car warms up; it immediately stalls. I did another smoke test, and the only smoke that came out was from the air filter and the IAC breather cap, which I think is expected.
So now I've installed a new intake manifold, new MAF, new 02 sensors, new IAC valve, new air temp sensor, new injectors, and new fuel pump. I have an EGR delete plate.
I think the only things I haven't replaced are the plug cables, coils, throttle position sensor, and crankshaft position sensor.
I'm going to try to do another data log tomorrow, and send it off to BAMA. But any suggestions from the factory five community are always appreciated.
Thanks
Joel

[Joel Hauser]

Here is my latest update. It's not good, but could be worse. I replaced the throttle position sensor (TPS), and extended the distance between the MAF and the air filter. BAMA suggested that mounting the air filter too close to the end of the MAF housing, as I had done, can cause idle problems. I was able to extend the distance between the two using a silicone rubber coupler and a 3" PVC L that I purchased at Home Depot. That didn't fix it. I then installed a new TPS; that did not fix it either.

So, BAMA wrote me a new tune which I installed last night. I haven't had a chance to run the car yet, but weather is expected to be nice this weekend, so maybe I'll take it for a nice long drive.

The good news is the engine runs purr-fectly on the road. The stalling only occurs in low speed turns as you clutch and down shift, and when approaching a stop.

Regarding the TPS, before replacing it I tested the voltage - over and over! When I back probed the TPS ground and signal wires, I got about 4.5 volts at idle, and about .9 volts at WOT, which is the opposite of what you're supposed to get. But if I back probe the signal wire and ground the volt meter to the engine, I got .9 volts at idle, and 4.5 volts at WOT. I got the same result with the new TPS. Is anyone familiar with this issue? I've looked on a number of mustang forums, and have found it discussed in a number of them. However, I haven't found an explanation for it, or whether or not it is even a problem. I've checked my wiring a million times, and don't see any place where I crossed them. I also checked continuity in the wiring harnesses, and everything seems to be as it should be, with all the wires going where they are supposed to go.
Joel

[Just puttering]

The TPS issue, my first thought would be the pos and ground is reversed? Or make sure the ground wire is ground. When testing from signal to chassis ground you are seeing the voltage on one side of the sensor, when checking from signal to the wire ground you are seeing the voltage on the other side of the signal wire. Check the voltage on the ground wire to ground make sure it is 0. You might be checking the pos to the signal wire?

I would check this out but i am having some of the same issues you are and right now the eec is sitting on a bench!

[Joel Hauser]

I installed the new tune from BAMA; regrettably the car still stalls when I take my foot off the gas and depress the clutch, but only when the engine is warmed up. But, inexplicably, I am now getting the correct voltage readings off the TPS.

I think the solution may be to just drive fast, downshift quickly in the turns, and never stop.

But seriously folks, this is very frustrating.

[Joel Hauser]

since my last post, BAMA has tweaked the tune again, and I've modified my driving habits. the good new is the idle and driving is overall a lot better. It idles more smoothly, and while it occasionally stalls on deceleration, the emphasis is on occasionally. I think the last time I took it out for a ride, it stalled only once, when I was turning into my driveway. I can live with that.

Last month I took the car to its first car show. It was "dad fest" in Albany, NY. The car was a big hit, partly because I was letting anyone who wanted to sit in it, especially little kids...but no food or drink allowed. But even those who didn't sit in it were very complementary. I also met a very nice family that is building a factory five cobra of their own.

Joel

[UnhipPopano]

Quick question, as the engine runs poorly at low RPM, and "He said he took it in trade from the previous owners who had been drag racing it", any chance, that the flywheel was replaced?

[Joel Hauser]

You know, it might have been. I am not a mechanic, and I've only built a couple motors; this was my first mustang motor, so I really wasn't conscious of what was stock and what wasn't. That said, the clutch was definitely not stock. The clutch disc was "X" shaped and doesn't have any springs in it. the pressure plate was also blue, but looked pretty standard. The fly wheel might be aluminum; I didn't think of checking it more carefully because I assumed it was stock. Recognizing that the clutch was not stock, I replaced the blue one with a stock clutch. If the fly wheel was replaced with a lighter aluminum one, could that be causing the stalling on deceleration? I think I'll put the car up on stands this weekend and see if I can get a good look at the fly week, maybe getting a magnet on it.
Thanks for the response

[Brad Smith]

Try to get your hands on equipment that will allow you to read live data from the ECU. If we can see what IT sees, we can figure out why it's doing what it's doing.

[Joel Hauser]

Hi Brad, the BAMA tuner I purchased allows me to do a datalog which is sent to BAMA for analysis. I think they are doing a good job from their end.

I've checked my flywheel, and found that it is an aftermarket aluminum flywheel. now I'm guessing that the lower mass of the flywheel is the cause of the stalling. I'm not going to change it, at least not right away, because (a) that's a pretty big job; (b) I've learned how to drive the car in such a way as to avoid stalling; and (c) I think it's kind of cool having a lighter flywheel because of the increased throttle response. My friends who have driven the car were really impressed with the acceleration.

Thanks for your input.
Joel

[Brad Smith]

Check with BAMA to see if they can raise the target idle rpm to compensate for it.

[Joel Hauser]

My engine is fixed; it turns out the ECU was bad. I bought a new rebuilt ECU from Flagship 1, installed a new BAMA tune, and all's well. The engine runs great; no misfiring, no longer running rich, and great power at all RPMs. BAMA was able to disable the PATS, so I didn't have to deal with reprogramming the key.
Such a relief.
Now onto the next project. Yard work.

[SSNK4US]

Yay!! I’m glad you finally got it all figured out. I’m just really sorry it took over a year and probably countless dollars.
Congrats and enjoy!

Kurt