OK Folks,
Needs a little help/direction with next steps in the trouble shooting process.
I have been building an ’83 944 SP1 car for a while, and it is pretty much complete, I just need to chase down this last (hopefully) issue. The car is an ’83 shell with an ’86 924S block. Here are the symptoms:
- Car starts and runs fine in the garage, revs smoothly to redline.
- No cold start apparatus, cold air valve and associated plumbing has been removed/blocked off.
- Once I get out on the track, runs well at lower RPM, but once it reaches 4200 rpm, it starts to stumble and cough. (within the first hot lap) Bring it back in, and now it won’t rev past the 4200 without stumbling, coughing and spitting. If you hold the throttle open it will try to rev, the spit stumble and die.
The car was not running when I got it, and I have gone through the motor, and most everything else:
- New fuel pump and filter (filter has been changed once since it has been running there was definitely still crud in the tank).
- Fuel Pressure tests good at the rail
- Reference sensors are both new, and the reference sensor wiring harness has been replaced all the way back to the ECU connector.
- ECU has been swapped
- TPS is new and set properly
- Air Flow Meter does have a slight “line” at the contact point, adjusted the arm slightly, but id does not appear to have worn through the conductive material.
- O2 Sensor is not connected
- Injectors did need to be “smacked” when I first stared the car up.
- Most of the rest of the engine harness is original, I am going to rebuild it over the winter. (Hoping to nail don the problem before I take it out).
I can swap parts with the best of them, I am hoping you (all) can point out some steps or areas I have not yet addressed. The challenging thing is you make a couple of changes/tweaks, and go out to test, but the problem remains. So, back to the garage, try something else (and then wait till you can get back to the track to test.)
Appreciate the help and thoughts in advance!
Bill
