Join Date: Dec 2010
Location: Nashua NH
My Ride: 89 Shelby Lemon
Engine: An odd mix of 2.2 and 2.5 engines.
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Hesitation and stumbling at certain throttle positions
So the car developed some new weird issues during the last race. At certain mid throttle positions it would randomly start bucking and stumbling. We replicated it in the pits, you could open the throttle ~1/2 - 2/3 and it wouldn't rev. instead it would fluctuate up and down a few times, then slowly build up. If you snapped it WOT it would act normal again.
On track it would occasionally stall out and die on shifts. As soon as you came off the gas and put the clutch in it would turn off, and I'd just dump the clutch and pop start it again. It also wasn't consistent in power delivery. At WOT you'd feel it pull, then back off, then pull again. Not always at the same RPM.
We ended up replacing the throttle body, and that seemed to help, but it did repeat the symptoms a few more times later in the day. The car has never done this before. We did have electrical issues the day prior. The O2 sensor wire bundle hit the turbo outlet and melted, shorting some things out (fuel, ignition, etc). Also caused a code 11 to be thrown, which really sent us on a wild goose chase. We did get those issues solved, but the hesitation issues listed above then greeted us.
I'm hoping that the replacement throttle body was just not 100% good and that really is the issue, but does anyone have other ideas? This race we were running the stock '89 computer with a '88 TII engine, with the '89 head and intake on it. (I know, it's a cluster-F, but you make due when you're racing cheap cars)
2.2 Turbo RWD Lemons project