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TPS signal oscillation/ noise, seems DME or software related.

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    TPS signal oscillation/ noise, seems DME or software related.

    Before I try to chase this issue some more, wanted to ask if anyone experience what looks to be a floating TPS signal? In Testo I am seeing two TPS1 values, one at 5v, one at 0.4v close (normal), this reads the throttle body sensor. When I click on either one, the floor is the low side value, but it fluctuates to 5v at about 30Hz (though this may be more related to the Testo sampling rate).
    The symptom is a lazy initial throttle response but work up top, which sort of makes sense as the fluctuations go to 0 as TPS approaches the 5v mark.

    I swapped the pins between TPS 1 and TPS 2, including the 5V input and the problem stays on pin 7 of the 60004. While chasing this issue, I've replaced everything and feels like I've tried everything. Initial thought was that some sort of H-bridge is being noisy, but with the ICV and Throttle Servo unplugged its the same. Things that have been swapped: DME (same software), pedal, TPS sensors, Throttle Servo. Checked wiring at least 5 times now, including each pin to ground and power. I haven't put a scope on it as I can't find it and need to order a new one.

    After realizing that Testo is showing two TPS 1 values (between which the signal oscillates), is it possible that each value is being sampled by the DME? I've disconnected nearly all other loads and inputs from the DME to sort of run it undisturbed and still seeing the same problem.

    Setup: E36 S54, MSS54HP, Bosch MAP, CSL base map from MSSTuning.com, Fuel pump on pin 10 (dumb relay control). Symptoms: Lazy throttle when TPS1 voltage is low (closed), occasional no throttle response.

    My next steps are to flash a different program, but wanted to ask if anyone has experienced this before?
    Attached Files
    Last edited by Pavlo; 06-13-2022, 08:18 PM.

    #2
    Was it OK with original/stock software? Did your issues began once you loaded CSL software?
    Which ECU do you have? non HP or HP?

    When you ask diagnostic information from the ECU the values are first read by the ECU from RAM and then processed on the diagnostic line. Sometimes TestO shows strange behavior. Do you have error codes?

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      #3
      This is in a swapped e36, so I’ve only ever had this program. I’ve always had a bit of a lazy throttle response that I tuned over with throttle maps, but I think this problem has been a problem from the start.
      I have considered that Testo has a bug as far as two TPS readings. I don’t have enough cars to try data logging. Though could try a friend’s shop scanner.

      I think at this point the only thing I have left is put an oscilloscope to see if this is a hardware problem and/or try a stock full flash and see where that gets me.

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