Ok so I am having a problem. I can set up the car just fine, part throttle, full throttle, cruise is just fine. When I come off the throttle, the revs will drop, and either catch at about 800 rpm stumbles or almost stalls to 100 RPM then recovers.
When I take my foot off the gas, it pins full lean, even if I force the system to still pump fuel. So it is one of two things
1) My spark control is bad or something with the ignition that I can't figure out. Everything has been gone through, there is one thing I need to check with Holley tech support. I have an adapter to run the tach. I am not sure if it should be on the MSD now that the Sniper is in or run off the "Tach out" on the Holley. From all that I can read, it doesn't matter. Losing spark on the way down would cause a false lean.
If anyone knows if something that will fool the Holley, please let me know. The Holley can control the timing but I would have to heavily modify a Holley dual-sync dizzy to fit It needs a 12V square wave output, not sure If I can get there with a trigger wheel. I am looking at the megajolt software tonight.
2) The other thing is it is registering a false lean for another unknown reason, be it a combination of head, header, intake etc... that will require an engineer to diagnose, and expertise far beyond mine. New intake gaskets, header,and a new O2 sensor after the Holley one broke (will get replaced under warranty), cap rotor, plugs just to make sure that it isn't something simple, has been done. Voltages look fine, worked with my NA setup.
The problem, as far as I can tell, is that the false lean, causes the EFI to dump fuel, then it dumps too much, on the way down to idle., floods it and causes it to stall and stumble. Can this be tuned out? I am not sure.
Maybe I am reading this all wrong, but it is the only thing that makes sense based on the fuel flow and the data and what I can cobble together. Any other theories are welcome.
It does idle nice, if I am out of closed loop, it is just every time I come to a stop, the stalling is just too annoying to overlook.
Below is the data.
On the left side, I forced open loop so the Closed loop comp stops trying to fix this. On the right, I have closed loop, and you can see the idle peak then drop. The red is RPM.
Below you can see how CL comp chases the spike lean in the AFR.