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Correct TPS Voltage?

This is a discussion on Correct TPS Voltage? within the General Help forums, part of the LSx Technical Help Section category; Are the TPS's on these cars adjustable? If so, what is the correct voltage? For instance on my 1990 Mustang ...

  1. #1
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    Dark blue metallic
    1999 Camaro SS

    Correct TPS Voltage?

    Are the TPS's on these cars adjustable? If so, what is the correct voltage?

    For instance on my 1990 Mustang I can adjust the TPS by loosening it and rotating it slightly until I get .98-.99 volts with the key to "Run" but the car not started.

    Is the procedure the same on the LS1? If so, what's the recommended voltage?

    I'm curious to check the TPS on my dad's car.

    I have searched but not found my answers. I did read alot that people feel the TPS to be a problem area on the LS1 and a cheap replacement part. Didn't see if anyone has checked/adjusted them.

    As a side note, my dad's Camaro occasionally stalls out when slowing down for a light or even offramp.

    I've done some basica maintenence on the top end sensors and it's running good but still does this. I wanted to check the TPS and do the fuel filter tommorrow.

  2. #2
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    Dark blue metallic
    1999 Camaro SS

    Bump. Anyone know?

    Been searching around, best I can find is mention of the voltage at WOT reported on a handheld tuner - and I'm not sure if that value is for stock or modified.

    Does anyone know what the TPS voltage should be with the car on "Run" but not started? Should I also check WOT?

    Thanks!

  3. #3
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    Dark blue metallic
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    OK, for reference, I found the info I was looking for. The TPS is not adjustable and the PCM actually accounts for any out-of-adjustment of the TPS. So unlike some cars where the base TPS voltage should be set, the PCM of the LS1 will compensate and set the idle based on that. That is good news.

    I know it's from another site, but here's where I found it (using google): http://www.ls1racer.com/phpBB2/viewtopic.php?t=1539

    And a snippet of text:
    Idle Info
    Sensor Info
    Throttle Position Sensor
    The Throttle Position (TP) sensor is connected to the throttle shaft on the throttle body unit. It is a potentiometer with one end connected to 5 volts from the PCM and the other end to PCM earth. A third wire connects from a sliding contact in the TP sensor to the PCM allowing the PCM to measure the voltage from the TP sensor. As the throttle is moved (accelerator pedal moved), the output of the TP sensor changes. At a closed throttle position,
    the output of the TP sensor is below 1.25V. As the throttle valve opens, the output increases so that, at wide-open throttle (WOT), the output voltage should be about 4 volts.

    By monitoring the output voltage from the TP sensor, the PCM can determine fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts of fuel from the injectors, and an unstable idle, because the PCM interprets the throttle is moving. The TP sensor is not adjustable and there is no set
    value for voltage at closed throttle because the actual voltage at closed throttle can vary from vehicle to vehicle due to tolerances. The PCM has a special program built into it that can adjust for the tolerances in the TP sensor voltage reading at idle. The PCM uses the reading at closed throttle idle for the zero reading (0% throttle) so no adjustment is necessary. Even if the TP sensor voltage reading was to be changed by: tampering, throttle
    body coking, sticking cable or any other reason, the TP sensor will still be 0%. The PCM will learn what the closed throttle value is every time the throttle comes back to closed throttle.
    Just thought everyone would want the info incase anyone else questions resetting the TPS for smooth idle.

  4. #4
    Veteran 0rion's Avatar
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    06 duramax

    There is an idle relearn procedure. For an auto it's basically letting the car idle in drive with the ac off and the on for the most part. I can post up the steps if you want them.

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