Sniper 2 on BP 347 - Initial Start - Idle Issues

[MakoGT350]

Hey All

First start on the BP 347 with Holley Sniper 2
Followed the Sniper 2 Wizard
In tank pump
Fuel pressure set to 60 psi
Supply line in to Sniper
Return line to the regulator then to the tank
Vac line from Sniper base to the pressure regulator
Vac line from Sniper base to distributor
With Idle screw adjusted in, runs steady at 1300-1400 rpm, TPS at 0 and IAC at 0
Backing out the idle screw, RPM will start to drop, but quickly starts to run rough and IAC starts to climb, but is erratic. Will then stall.
PCV valve is not stuck
Have not checked timing, but seems unlikely to be the issue given the dyno run by BP and no change by me
Checked for vac leaks with a bit of starting spray around the intake manifold flange and sniper base plate - seemed to be a couple of spots around the base plate and intake flange.
Checked torque on intake bolts and found a couple that got snugged (used 20 ftlbs and the right torque sequence)
Replacing the carb gasket and going back together

Couple of questions:
Does it sound like anything other than a vac leak?
Looking at Sniper trouble shooting and it says power and ground should go direct to battery, anyone here have experience with buss bar vs battery for Sniper power and ground?

[rich grsc]

All power direct to battery

[gbranham]

Like Rich (and your Sniper instructions) said, direct to battery. Not sure why folks think this is merely a recommendation

Greg

[Papa]

What's the temperature reading when you start adjusting the idle screw? You want to be at 160+ before trying to make adjustments.

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 on the primary shaft 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.

Tech Tip: If the IAC percentage is reading 0% but the engine is idling higher than programmed idle speed, the throttle plates need to be closed (counter-clockwise on primary throttle screw). On the other hand, if the IAC percentage is at 100%, and the engine is lower or maintaining the programmed idle speed, the throttle plates will need to be opened (clockwise on primary throttle screw).

NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160°F!

[rich grsc]

Greg, real men don't follow no d-mn instructions. :eek: or read them. :rolleyes:

[gbranham]

Greg, real men don't follow no d-mn instructions. :eek: or read them. :rolleyes:

Hah! I'm not a real man, apparently. I'm good with that...my EFI setup worked great from the get-go. :)

[rich grsc]

Ya, I sorta like things to work too. I have 3 boxes of new Holley Terminator stuff here right now. I have spread it out on the living room floor a couple of times, and poured over the instructions a bunch of times. Before it goes on, I'll do it some more

[MakoGT350]

What's the temperature reading when you start adjusting the idle screw? You want to be at 160+ before trying to make adjustments.

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 on the primary shaft 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.

Tech Tip: If the IAC percentage is reading 0% but the engine is idling higher than programmed idle speed, the throttle plates need to be closed (counter-clockwise on primary throttle screw). On the other hand, if the IAC percentage is at 100%, and the engine is lower or maintaining the programmed idle speed, the throttle plates will need to be opened (clockwise on primary throttle screw).

NOTE: Do not attempt to set the target idle speed and IAC position until the engine is above 160°F!

Thanks - got the operating temp above 160

[MakoGT350]

Greg and Rich - thanks for stopping by...appreciate the multiple insinuations that I didn't read the instructions.
I got that part covered, and nothing in there about a vac leak. ;-)

Was just wondering if anyone had any thoughts about why it calls for a direct connection. Given that a power distribution system (buss bar, fuse panel, etc) is pretty standard on nearly every car, everywhere.

[Papa]

Have you tried running without the vacuum line on the fuel pressure regulator?

[MakoGT350]

Have you tried running without the vacuum line on the fuel pressure regulator?

I have not, but I can give that a shot once it is back together - I am always up for some process of elimination. Thanks for the idea.

[cv2065]

Regarding the power feed, here’s a good forum exchange on the Holley site that might help. For the record, my MSD box also asked for a direct line to the battery.

https://forums.holley.com/forum/holley-efi/sniper-efi/32412-direct-battery-power-questions

[Blitzboy54]

I am sorry to hear you're having trouble. I had a lot of problems with my Sniper 1 but had thought the 2 had worked those issues out. For all the head aches I had with that thing I will say this, the tech support line was decent to very good. If you give Holley a call they can be helpful. Ideally it should be done when you can be near the car but you don't have to be.

[Norm B]

The Sniper doesn’t handle low voltage or unstable power well. Any connection not at the battery is subject to draw down and interference from the other circuits on that connection. Direct to the battery is the cleanest and most stable power available.

Norm

[JMD]

I would remove the vac line to the fuel pressure regulator and the distributor but make sure you have the correct vac line to your pcv valve. BP actually says not to use vacuum advance on these engines. I removed mine and it ran much better. You can add it back later if you want to get the vac advance dialed in, but I would remove it for now. And you don't need a vac line to the FPR at all. Just a steady 60psi will work just fine, you don't want it changing with vacuum.

Also I would check the distributor springs. I suggest using the medium springs. I tried the lightest in my Pertronix distributor and led to a lot of surging at idle.

I also suggest double checking your timing at idle. If you're between 10-14 degrees advanced you should be fine. Don't assume anything is set the way it should be, even when you get the engine from a reputable engine builder. Ask me how I know...