FiTech EFI system
Hard to say. What's your afr do when that happens? Using timing control? What's the advance do when the rpm drops? How high does the iac go?
What's your initial timing at the moment? Is it verified with a timing light?
Mayne data log the idle and post some numbers or a screen capture of the data.
It could very well be a misfire or the timing is moving to try and hold idle and its not helping. Could be too lean or rich of an afr. Could be the learn value moving too fast, or the afr jumping too much at a time.
This was exactly what I had and reducing the idle learn and loop rate helped a bunch. As did making the afr jumps smaller.
Thanks !
Not using timing control for now. Afr jumps lean. idle AFR set at 14.10. tried it richer and leaner and it made no difference in the random drop off.It will be idling at 840 and then drop off. IAC will jump to 30-50 to compensate.
I put a new PCV VALVE on and no change. Blocked off the PCV Valve with my finger and RPMs still dropped off. Appears random, and will hold for a minute or 2 sometimes, then fall.
Other interesting thing, if I have it in gear, then it won't fall??
Initial timing 14, verified by timing light. Have to see if timing is changing when it drops. Not using any vacuum advance at this time.
No fault codes on the ecu.
Going to check for a possible vacuum leak under the throttle body, as that's the only thing that was off the motor since it worked ok. I have changed the idle loop up and down already.
Unfortunately I have to work during the day, so, may not get back to it till tomorrow night