OK what are the symptoms of a bad TPS?
My TPS took a slight whack when I changed the radiator (dont ask) and has a small crack in the side. The SES light comes on, and it idles and accelerates erratic. Is this most likely the TPS?

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1980 Camaro, '88 Police 350 engine, Headers, full exhaust, completely redone, my baby!
1988 Iroc-Z L98, MSD 6a, Accel coil, K+N's, Airfoil, Coolant Bypass, Flowmaster, Gears, Late model Bose, I like the 80 better

 

Correct me if Im wrong, but that sounds like you messed it up. It might either be broken, or hitting it caused it to be misset.

The TPS does exactly what its name says, (Throttle Position Sensor), which allows your computer to adjust air/fuel ratio and I think timing, so breaking it could really cause your car to run crappy like you say. Your car only runs as well as the condition it sensors are in. You will probably have to cough up 40 bucks and replace it.

 

you can check it with a digital voltmeter. Turn the key to the run position and poke the voltmeter leads into the top two ends of the plug on the TPS sensor. Fully closed position should be .54 volts.

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'89 Formula 383 TPI

 

Make sure as you open the throttle (engine off please) that the volts increase steadily as you open it up to a max of around 4-4.5 volts.

 

i just replaced mine 25$ at autozone use the 2 top terminals on tps to check voltage the way i checked mine is at idle if u loosten the litte tork screws and move the tps and the idle changes up or down it is probably fine. when mine went bad it did nothing to the idle when i moved it and the car WILL NOT excellerate at all well thats my 2cents hope this helps

 

Set your minimum air first, (IAC), that way you KNOW you are at the proper idle when you set your TPS. I know you probably didn't do anything to mess it up, but you might as well do it anyway while you are setting your TPS voltage. There is an article on how to do it in the Tech section.

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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, TB Coolant Bypass, Ported Plenum, Modified MAF, Syclone Fuel Pump, JET Airfoil

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/