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Holley Sniper EFI and Hyperspark. Help needed.

Like I said, between 1-5%. I have a Sniper myself. That's what you want.

And again, if you can't get the AFR to stay at what's commanded then like the OP is now grasping there is something preventing it from happening. I'll say I have had a similar issue myself with exhaust leaks. When I first started the tuning process, the headers and exhaust were nice and tight. With more heat cycles things loosened up a bit and the AFR became inconsistent. Tightened up the connections, problem solved. Honestly, I still battle with it, just the nature of the beast - the headers just don't seal as well as they should. Find the intake or exhaust leak and things will smooth out.

And as I stated earlier in the thread, the 02 was the least likely culprit here. Suppose it could have become contaminated if there was enough unburned fuel in the exhaust but that wasn't the fault of the 02, it was a result of an out-of-range condition upstream.
I replaced the O2 so now its running well again. I just need to figure out the IAC. Either its a vacuum leak or its the fact that I missed the step to turn off the idle spark when adjusting. Which I know for a fact I did not do. So hopefully that will cure it and hopefully it wont be an intake leak. Seems more simple to adjust the IAC rather than pull the intake. Will update with my findings.
 
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when you turn the idle screw to open the throttle the IAC #'s should come down, is it idling at the RPM you entered into the software
 
Didn't watch that video but have you tried the "duct tape" method to set the IAC? Worked great for me. Basically you cover the iac port with duct tape, start up and adjust idle to 50rpm to below the idle rpm you want. Shut down. Remove the tape and restart. Idle will go up into the range you want and IAC comes back down. It's been awhile. May be missing a step needed in the handheld. Found the info on EFI Systems Pro site.

https://www.efisystempro.com/efi-pro-hangout/holley-sniper-installation-startup-troubleshooting
 
Didn't watch that video but have you tried the "duct tape" method to set the IAC? Worked great for me. Basically you cover the iac port with duct tape, start up and adjust idle to 50rpm to below the idle rpm you want. Shut down. Remove the tape and restart. Idle will go up into the range you want and IAC comes back down. It's been awhile. May be missing a step needed in the handheld. Found the info on EFI Systems Pro site.

https://www.efisystempro.com/efi-pro-hangout/holley-sniper-installation-startup-troubleshooting
Thats the site I bought the O2 from. I have not tried the duct tape method but Im sure since I didnt disable the idle spark that was my issue. But we will see.
 
Just lowering the target rpm should back off the iac.
Raising the idle timing advance will lower it as well.
 
Just lowering the target rpm should back off the iac.
Raising the idle timing advance will lower it as well.
I have it set for 750 RPM and the idle timing is around 15 degrees. I guess I could go to 14 or so without issue.
 
It will likely idle better at 25 degrees btdc.
It will start better too
 
If using the wizard and not a specific "tune", I believe the initial setup can affect idle as well. I redid mine in the beginning and went back to "Stock Cam" in the settings. It ran/idled much better. The small block has around a .490 cam in it for reference. Guessing it has to do with vacuum signal. It may be worth a shot if nothing else works.
 
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