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trouble with throttle position sensor circuit

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Old Sep 18, 2005 | 07:33 PM
  #1  
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From: Desert
Car: 1991 Z28 Vert
Engine: 383 single plane efi
Transmission: T-56
Axle/Gears: 8.8 with 3.73s
trouble with throttle position sensor circuit

I have started to have a lot of trouble with the throttle position sensor's circuit. I say circuit because I am totally stumped on what it could be. Here is the problem: I drive or sit in park while monitoring everything with tunerPro. I get very false readings from the TPS. I will have the gas pedal/throttle totally not moving and recieve a reading that will fluctuate all over the scale. I have had it sitting at idle and give a voltage reading of .55 to .00 to 2.3 to 4.3 back to 1.5. And that is all in the course of 1-2 seconds.

I have set the minimum voltage reading many times. I have replaced the old sensor with a new sensor. Both read good with a DMM though. I have followed the wires all the way back to the ecm and found nothing bad. I have tried it on 3 different 730 ecms. I recieve no ses codes. Please do not post the 'How to set min. TPS voltage" article. Where should I go from here?
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Old Sep 18, 2005 | 08:20 PM
  #2  
Tibo's Avatar
Thread Starter
Supreme Member
20 Year Member
iTrader: (15)
 
Joined: Jun 2003
Posts: 5,028
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From: Desert
Car: 1991 Z28 Vert
Engine: 383 single plane efi
Transmission: T-56
Axle/Gears: 8.8 with 3.73s
Just went out and double checked all of the voltages with a DMM. I do get a 5 Volt reference signal, I get the correct voltage at WOT and closed throttle. I get the correct voltage from the black lead to the positive battery terminal. also the correct voltage across the black to blue lead.
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