91' Vert is falling on it's face :/
 

Hey guys, I have a 1991 s5 vert. She will start fine. Then will Idle erratically once warmed up. the rpms will climb from 840 to around 1000 in about a second or two. then fall back down. This continuously repeats. Once I get driving and I put my foot down, the check engine light comes on. From this point if I apply any more than about half throttle, the engine will fall on it's face. rps drastically drop and the engine sputters a terrible amount..

What could possibly be the problem??

thanks in advance
-RX7FREEK-

Wrong section. This should be in the 2nd generation specific, not build threads.

Anyways, the throttle position sensor is probably out of adjustment.

http://www.rotaryheads.com/PDF/2nd_gen/

Section 4a of the 89-91 manual will tell you how to adjust it. You can also make a little checker with some LEDs, and there are many many threads about it here. Use the advanced search feature and do a title only search for TPS checker.

Yeah your TPS is probably bad, i had the same issue and replacing it, took the check light off. See what code the check light throws at you.

Thanks. as soon as I can afford a new one I will try it out and update you all.