Vehicle Will Not Exceed 2000rpm, But only while in Gear.
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Joined: May 2018
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From: Florida
Car: 1991 Pontiac Firebird Formula
Engine: 5.0L 305 TPI
Transmission: 700R4 MD8 Automatic 4Spd.
Vehicle Will Not Exceed 2000rpm, But only while in Gear.
Three months ago I completed my engine swap from a 305 TPI To a 350 TPI. When the swap was completed I started going through all the little things that come about after swapping an engine as well as fixing all the things that were broken along the way. Anyway. Post swap completion, we got the Car back on the road (91' Firebird Formula 5.0tpi to 5.7Tpi) and Instead of feeling a slightly more power (Like I expected) the car would barely get out of it's own way. After that we cautiously drove it back to the dealership where I work and began running through all the possible scenarios. Earlier this year we purchase a genuine Dealership service manual for this particular car and with a very old scan tool (Vetronix Tech 1A) we began our diagnostic process. The vehicle had set a code 43 The check engine light was steadily on, So we readjusted timing and eventually found the4 Knock sensor itself to be at fault. After replacement the code took a vacation But the problem still remained. Only now, Instead of the check engine light being on steady, It simply does not come on at all. using a scan tool we can verify that the system is detecting knock between 1800-2000rpm before it retards the timing. I Checked every article of the ESC Circuit. and when I found nothing, I replaced every item that was of suspicion. From the ECM, ICM, Knock Sensor (Again) all the wiring between each component and probably more that I just can't remember right now. The engine itself is in excellent shape. I purchased it from Hawks and made sure nothing was out of the ordinary. The engine makes no actually knocking or pinging sounds when at that RPM. But here's the kicker. When the car is in park. I can reach redline and nothing bad happens. no slug, no miss, no nothing. Just the sweet sound of a happy engine. But put it into gear and it won't exceed the 2000rpm threshold. I've exhausted just about every probability. Even gone as far as to replace the fuel pump, Sender and filter. and it help. but not by much. At this point I'm questioning the fuel regulator and injectors; as they were one of the only components that I didn't replace before installing. Before suggesting anything please know that I do have a correct Chip in the ECM And these were 350 Injectors but their operation is questionable. Any help would be appreciated on this matter.
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