Help, is this a bad TPS?, Diagnosing

[joeym4130]

Still working on it...(idle surge)
Today might figure the TPS has shit the bed. Probed the terminals on the TPS with the key on, didnt get any readings(have to try a different Voltmeter, this is el cheapo and i dont trust it so have to check readings again tomorrow). For the hell of it, unplugged the TPS and started her up, and she ran the same as with the TPS connected.... what differences would there be if my TPS was working and started the car w/ it disconnected. Because she ran exactly the same idle surge range with the TPS unhooked. Thanks....

 

[joeym4130]

anyone? i hate bumping my own posts up...just that a guy is offering me a TPS kinda cheap and i might buy it, just want to know what u guys think...especially about the car behaving the same with the TPS connected or disconnected...thanks a lot

 

[CurtTSI]

I once had a bad TPS on my 91 Talon and it would just buck occasionally while driving. Don't know whether it would cause an idle surge if it was completely dead. On my car, the bad TPS set an error code in the ECU, which told me what the problem was.

 

[joeym4130]

hmm ok.. i unplugged the TPS and started the car with my logger in too, and it didnt throw any codes on my ECU...weird....

anyone???? know what (if anything) would change between starting the car with TPS plugged in vs. with it unplugged? as mine was no different
thanks for the help.

 

[CurtTSI]

Here is a little more information about my experience with the bad TPS. When I did a resistance test on the TPS, it checked out OK. This was in spite of the fact that an error code was set in the ECU. Not having a data logger, I hooked up wires between the TPS and the connector plug so that I could tap into the voltage signal being sent to the ECU. I connected this to a digital voltmeter that I had taped to the outside of the windsheld so that I could observe it while driving. Usually, the voltage signal was smooth and corresponded to the throttle opening. However, when ever the engine bucked, I noticed that the voltage momentarily went to zero. That is how I confirmed that the TPS was actually bad.