88BlackBirdGTA

Ok, a friend of mine bought a car about a month or so ago, and it ran fine at the time and for a while. It's an 89 rs. Orriginal 700r4 tranny(as far as I know) but supposedly the motor is now a 350 tbi out of a 91 corvette instead of the 305 v8 that was offered. I don't remember gm offering a tbi in the c4 vettes tho. Unless they changed the intake over to it when installing. but anyway, the problem...when started up it'll stumble and die multiple times. I have to rev it up to keep it running. And then the rpm's will just jump around to where it nearly dies but jump back up. It'll do this for several minutes. Then once I start to drive it, it'll kinda lag out a bit but then run fine. It will idle relatively high tho. About 3500 or so. After some more driving tho it sometimes goes down to around normal. Possibly a fuel problem with the injector? Or a throttle solenoid/positioning type sensor?

88BlackBirdGTA

Any ideas at all? Much appreciated

Jesse Boggess

having the same issue with my 92 rs. Do you also experience white smoke and gas fumes?

88BlackBirdGTA

No fuel smell that I'm aware of. But I believe there's a little smoke out the pipes when I get on it to keep it running. Other than that nope

NinjaIzuna

I have this same issue with an 89 camaro rs with the 2.6 v6. I believe its the Throttle positioning sensor. When I purchased it it looks like it was cut at the connector.

https://i.imgur.com/maq0o.jpg

https://i.imgur.com/fAeWC.jpg

What I did to get it running even with this issue is I adjusted the throttling screw to throttle higher to prevent the stalling and not have to rev the engine. However this is only a temp fix and I suggest you pick up a new connector and test the Sensor its self.

ASE doc

Of course, before replacing any sensor, test it. The TPS receives a 5v reference and ground from the ECM and returns a voltage signal between .5 at closed throttle to 4.5 at WOT. Use a voltmeter to test between pin B and ground while you slowly move the throttle from closed to open. The voltage should change smoothly with no glitches or drop outs.

Honestly though, your problem sounds very little like a TPS issue and more like a coolant temp sensor issue. The CTS is the two wire(yellow wire, black wire) sensor at the front of the intake manifold. You can test it for resistance. It should read about 3,400 ohms at 70 degrees(cold engine) and about 180 ohms at 220 degrees(hot engine).

newagereject

Try looking at your idle air control as well, if it does not move freely in your hand then its shot