my tps is posessed. help.
 

thought maybe You guys could help me. I absolutely can not get my tps to read right. with key on engine off it reads perfectly. when I start the car it only goes to 30% at 3/4 throttle. I' ve tested the tps and replaced all of
the wiring to the pcm. thanks for any insight you guys can provide. I've never seen anything like It. Another crazy thing is my bank 2 o2 sensor reads low too and I KNOW its not lean.

could it be in the tune? I mean Im at a loss on this one.....

Forgive me if I am wrong but the throttle body I have recommended .5 volts at idle position with the ignition on but not running and 4.5 volts at wide open throttle without the engine running. Why and how are you checking yours with the ignition off?

Key ON engine off reads normal.

ENGINE RUNNING-does not read properly.

I'm using vcm scanner to watch the tps.

See I knew I was wrong!
I am having an issue with my TPS and want to make sure I am setting the voltage correctly. I have an adjustable ring in behind the TPS. The old TPS would only adjust down to 1.1v so I changed it and now its down to .83v. Professional Products recommended .5v but it aint happening. Anyways with the engine running and the TPS set at .83v I am getting a code flashing stating my TPS voltage is too low! Where are you wanting the voltage say at idle? I know .83v is too low for some reason. Do you think there is something in the tune that could cause this in both of ours? I checked my voltage unplugged and I am right at 5v. The TPS is a rheostat and unless the voltage is incorrect prior to the sensor it must be the sensor. I see you stated you replace the wires but did you keep the same plug to the TPS? This fuel injection system to me is confusing as hell and I am having a really difficult time understanding it as a whole.

at idle and 0% throttle it should read .48-.53
at WOT it should read 4.80-4.95

Double check the wiring.
My new harness had the 5v and the reference wires reversed on the TPS connector and it drove me crazy until I figured it out. The PCM saw a voltage rise, but it would not read within the desired voltage range.
Good luck.

Jim

Jim. It reads perfect with the key on engine off. So its not any wiring with the tps. Even though, I've quadruple checked it.

Does it zero out at idle just fine? I went through this same problem with a friend's 2000 Grand AM. I replaced the TPS twice, checked the wiring, everything was good but it wasn't reading right. Finally, my dad told me to disconnect the battery overnight and try again and sure enough it worked perfect.

He is a mechanic and said they used to have problems with older PCMs where the TPS sensors wouldn't read right unless they did that- something about the previous TPS ranges being "etched" into the module and it needs to completely drain to reset itself.

It's free and easy, might want to give it a shot. If that doesn't work and you are sure the wiring is good, I'd say you have an internal problem with the PCM.

Lt1pwr. I will try the battery. The tps has been slotted and zeroed. If the battery thing doesn't work ill be sure it the pcm.

anyone? replaced battery and tried another pcm. still no luck.

I, myself, have had to replace 2 faulty TPS sensors on the same car 6 months apart. check the plugs for corrosion and check to see if the TPS swings smoothy on a meter. I opened one up to try to fix it, they are to delicate. Some ppl spray the engine bay down too, water can get in.

What throttle body are you using?