I have been messing with my TPS trying to get my idle just right. I adjusted it out using the light method. Idle still surged about 50rpms. Not to bad I know, but I want it perfect if I can get it.

Today I pulled my carpet back to gain access to my ECU so I could try to adjust it to 1V. With the car running, I adjusted it out to about 1V. It would bounce around from about .997-1.008. Is the TPS voltage supposed to jump around like that while it is Idling?

Next I turned the engine off and turned the key to the on position. To my surprise, it jumped up to 1.045 volts. Shouldn't the voltage stay same, regardless of weather the engine is running or not?

Should I adjust my TPS with the engine running, or the engine off?

I should also add that I have 88 TII with a large SP. The BAC has been removed but it idles right around 750. Thanks in advance

 

Adjust it using a multimeter to measure the resistance. The readings never tend to stay exactly the same, at least in my experience. Slightly off is no big deal though.

 

No. Adjust it and read the output at the ECU like you have been doing. It should be approx one volt with the engine idling. Mine does not jump around at all. Are you sure the tps is attached to the throttle body good?

It can read low as 0.9 or 1.05 and there will be no ill effects at all. Been there, done that. Make sure the engine is HOT when you take a look at the output of the TPS.

IF you suspect the tps being bad. then disconnect its plug and ohm out the TPS per the online fsm. Look for irregular readings as you slowly depress and let up on the plunger. If you have a old *swing* meter it will be easier to see a fault in the pot. That's about the only use I have for a analog meter over a digital meter.

Series five outputs for the TPS are different than the series four. The Fuel section of the fsm has a couple of pages called CONTRO UNIT and it gives the output/input of each pin on the ECU with the car idling or just with the key to ON. The series four says the TPS output to the ECU with the car idling should be approx 1vdc.

I can adjust my tps using the two led light method and the result WILL be approx 1vdc when I get through. Which side of 1vdc all depends which way I turn the TPS screw to get the desired result of only one LED being lit.

I can't relate to the voltage jumping around. I always see a solid reading, whether .97 or 1.05 or whatever. It does not matter if I use the Radio Shack meter or the Fluke. Always solid.