Thought someone here might have a suggestion on what is causing a rough running issue with my 964 Turbo.
I took the car out for a spirited drive over the weekend and it ran well. On the way back home, I start to notice a little rough running... the car dies as I'm releasing the clutch from a stop (in the middle of an intersection). Restarts no problem and I limp it up the road.
Pop the rear and see the O-ring on the intercooler showing. Figure it's a vacuum leak that is causing the issue. I limp the car the rest of the way home and put the IC back on correctly with a new O-ring. Car fires up fine, but still has the erratic tach / rough running problem.
I have two videos uploaded of the car idling here. I started the car cold about 3 minutes before I started the first video. The second video is of the car dieing a minute or two later while at idle -
YouTube - 964T - Rough running
YouTube - 964 Turbo Rough running2
The car has an AEM standalone engine management system and an MSD ignition amplifier. Assuming this was a bad MSD unit, I replaced the old box with a new one but the problem persists.
- Battery voltage is in the 12-13 range at idle
- TPS looks to be acting normally
- Closed loop O2 control is not active below operating temp, so the issue isn't the wideband oxygen sensor
- I can hold revvs at 2k rpms and still have the erratic jumping around (this leads me to believe the problem is not an idle air control motor or idle control related).
Seems like this has to be ignition or ignition control related, but I am not familiar with the Porsche ignition systems. Does this look like anything you guys have seen before?
Thanks in advance!
Best,
John