Hi All,
I'm having a strange issue that I can't seem to find anyone who has had the same issues and was wondering if anyone can point me in the direction of possible causes.
When I try to go 100% WOT from maybe 30-50mph the engine goes to spool up and then backfires like crazy and the engine stalls. The backfiring continues for a bit, but no combination of throttle positions can bring it back to normal operation, I need to put the car in neutral while rolling and then turn the key again to get it running again.
The transmission downshifts from 3rd/4th to 2nd when all this occurs as it should and the revs start to shoot up but suddenly ends with the backfiring.
Cruising and mid throttle acceleration is all good, idle is fine but a little high (950-1100rpm)
I have a couple of ideas of potential causes but was wondering if anyone can either help me out with the cause, or at least understand what would cause the backfiring and stalling.
1st idea is that the engine is just getting completely flooded with fuel, enough to blow out the spark and stall the motor. But I don't think the tune would be out that much, and I can rev the engine to those same ranges when staying in a particular gear and the issue doesn't occur.
2nd idea is valve springs, I know the ones I have are a bit soft for my motor, but I would suspect that would cause some valve float up high, but haven't ever heard of someone experiencing these symptoms from it. They're only slightly out of recommended specs anyway, but had been shimmed to get the pressures close.
3rd idea is in a lazy effort, I hardwired my neutral/park switch to ground to bypass my broken safety switch. Is there any chance this is telling the PCM it's in neutral and kicking in some limiter that would shut off the engine indefinitely?
4th is that possibly the PE or transient fueling is not set up for SBC and is still using the LS1 settings?
5th is that the motor is pulling that much fuel that the fuel pump can't keep up and it starves it.
Any ideas?
I've attached the tune. A log is also included, but I hadn't induced the issue on this run.