Tps causing high idle

[brinx182]

'89 c1500 5.7 tbi with 700r4
Timing is set to 0
New sensors all around (truck sat for a long time)
Tps sensor is showing .49 volts with key on and not running, once it's started it jumps to 1.3-1.5 volts. Idles high around 1500-1700
When I pulled off the old sensor one of the bolt heads snapped off leaving a "stud" and installed the new one with the remaining bolt, the other side slid over the broken bolt. No movement in the sensor itself that I can detect (trying to wiggle it vigerously) and no change in voltage fully closed with engine off. I have a bolt set ordered and am waiting, just need to know if I got a bad sensor or if the broken bolt is the issue.
If tps unplugged during idle it goes back to a perfect idle, replugged it raises again

 

[PlayingWithTBI]

Tps sensor is showing .49 volts with key on and not running, once it's started it jumps to 1.3-1.5 volts.

Unless you have some electrical supply issue it has to be moving. Either your issue is the broken bolt or maybe the throttle shaft is moving when under vacuum? Just for ***** and giggles, I went back on some data logs on my 88 and they all show the same voltage (.45 by the way) when KOEO and at idle.

Try checking voltage on pin B (Grey wire) with KOEO and then at idle. If it doesn't change, I would think you have a good power supply. Then look at voltage on pin C (Dark Blue wire) to confirm your ECM is seeing what it should. Also ensure you have a good ground at pin A (Black wire).

Then, try wiggling the throttle shaft up/down, forward/back to see if your feedback changes. If it does you probably have worn shaft bushings.

You can try moving the TPS while running to see what's up with it too.

This schematic is from an 88 but s/b the same as your 89. HTH

You must be registered for see images attach

 

[brinx182]

Unless you have some electrical supply issue it has to be moving. Either your issue is the broken bolt or maybe the throttle shaft is moving when under vacuum? Just for ***** and giggles, I went back on some data logs on my 88 and they all show the same voltage (.45 by the way) when KOEO and at idle.

Try checking voltage on pin B (Grey wire) with KOEO and then at idle. If it doesn't change, I would think you have a good power supply. Then look at voltage on pin C (Dark Blue wire) to confirm your ECM is seeing what it should. Also ensure you have a good ground at pin A (Black wire).

Then, try wiggling the throttle shaft up/down, forward/back to see if your feedback changes. If it does you probably have worn shaft bushings.

You can try moving the TPS while running to see what's up with it too.

This schematic is from an 88 but s/b the same as your 89. HTH

You must be registered for see images attach

Gray wire is consistent between koeo and idle at 5 volts.
Ground is consistent
Pin c is moving between .5 and 2 volts randomly now with no movement in sensor or throttle. guess it's time to get another sensor and hope I don't break another bolt