I recently installed an larger turbo and FMIC in my car(and a HG). When the car is warmed up and between 10-18" of vacuum(idle to light cruise), I have a very apparent miss. Before installing the turbo and FMIC, the car ran perfectly fine. Also, when I'm in the throttle(up to 21 psi), the car runs perfectly fine.

I have tried new plugs, different plug wires, cleaned the IAC, and shaken/wiggled all electrical connections in the engine bay. Nothing seems to affect the miss. The old plugs showed good color and were in good shape. My a/f ratio is good too.

I want to trick the computer into thinking the engine is still cold. Is there a way to do that? Unplug a specific sensor, run a jumper wire, put a certain voltage somewhere--How?

If I trick the computer into thinking the car is cold and the problem stops, I know I have an electrical problem. If I still have the miss, I have a mechanical problem.

Have a good day!
Michael

 

Are you still useing the Ford TFI or aftermarket ??
I went through the same issue...we also had to adjust Haltech computor settings to feed "8 volts" to hall effect senser..
I guess thats why it starts intermitant miss when it gets hot? The hall senser is over heating electrically and or sending corrupt signals to ignition driver...It fixed my problem... Also check what settings you have on dwell in ecu ? hth Graeme

 

Yes, I'm still using the factory ignition setup and ECM. It all has less than 7,500 miles on it though (distributor, coil, tfi, etc) because I replaced all of it in an effort to track another problem down when I first got this engine going.

I have an MSD Digital 6 that I hooked up to see if it would help, but it made no difference.

I 'ass'umed that if it was something like the pickup signal, I would have the miss all the while in the throttle also...not just at light cruise and idle. So in your case, you believe the ignition module was overheating?

Although I have an EEC Tuner to install, I'm wanting to get this last problem figured out before turning it up another notch.

Have a good day!
Michael