TPS Question
 

I have a question about TPS adjustment. I had it adjusted perfectly and it was fine for 6 months then I installed a complete exhaust and a Walbro. Later I took it to the strip. After the first run it wouldnt idle and was backfiring. I checked the TPS and it was way out of adjustment. I adjusted it and it now runs fine. Does anyone know what would cause it to loose its adjustment? Thanks

If you are adjusting by voltage - a bad ground will make the setting float.

I adjusted it by measuring resistance at closed throttle it should have been around 1000 but it was at 400.
It didnt go out until I raced the car.
Thanks

Mine was erratic when I first got it.
When I checked it with a cheap analog meter, the needle would jump back & forth as I slowly opened the throttle.
I shot some spray contact cleaner in the plunger, worked it in, & blew it out.
That smoothed it right out.

Make sure NOT to get contact cleaner "into" the pot. Contact cleaner will dissolve the carbon track that actually forms the resistor and thus destroy the TPS.

To the original poster, a number of things can cause it to spontaniously go out of adjustment. Especially if the TPS was set with the car cold. Make sure the throttle is not hanging up on something, and clean the metal contacts in the TPS plug.