Quote:
Originally Posted by Mikey
Situation:
Bought a '91 368 Corey Henderson built Z with 25K miles a few months ago. Drove it home from WI to FL. Behaved the whole way.
Once in FL I had opportunity to do a WOT run to 7100 rpm in 2nd gear. It hard stumbled (coughed) once for a split second around 3200rpm but otherwise pulled strong. Repeatable event.
Moved from FL to TN drove the car up and behaved all the way.
This morning it was 38 degrees. Leaving neighborhood in 1st gear 20-30% throttle the engine exhibited a 2hz stutter as if I was on/off throttle in the 3000-3500 rpm range. About 6 or 7 "coughs" in a row. Cleared up above 3500 rpm. Was able to repeat it immediately after but no more. Car seemed fine afterwards except for the single cough/shudder that is fairly repeatable as described above.
Seems only to do it in 1st or 2nd. Not 3rd or 4th.
I've put 3,000 miles on it with no other issues.
Thoughts?
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Does this happen when easing into the throttle at that point or with a more rapidly increased amount of throttle(ie jump on it)? Is the issue worse with colder ambient temps? Where is the MAT sensor located?
3000rpm w ~ 20% TPS is where ECM goes into PE mode. I had a similar issue a couple of years ago. Crossing into 3000rpm it would seem to breakup a bit then go on. It would act like a miss.