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Why is my engine acting worse with new TPS?

I have a 1991 Buick Century with a 3.3L V6 and the check engine light came on and off and on and off this past week and the transmission wouldn't shift when the pedal is like at 50% to WOT and the speed would drop and the check engine light wasn't on and i wanted to see if a code was stored in the ECM. I got home and did the paperclip method because i couldn't find a OBD I scanner anywhere and i got code 22 which means Throttle Position Sensor voltage low and i went and spent 70 bucks on a new throttle sensor. I put the new sensor in and reconnected the battery and started the engine and the check engine light was still on and didn't turn off and now the engine shakes and then dies. I was surprised and confused at the same time. I did the paperclip method again to see if there was another code and i still got code 22 and only code 22. I checked the wiring to the TPS and everything was solid and good. I don't know what to do now.


2 Answers

  • 6 years ago
    Favorite Answer

    That TPS has to be adjusted. You would need to loosen the screws and rotate the TPS until it is giving the correct voltage. You can read the voltage with a multimeter, or with an OBD1 scanner.

    Source(s): 34 years in the auto business
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  • 6 years ago

    A fault code doesn't tell you "What is Wrong", It tells you that the ECU is not seeing what it expects to see on one of its inputs/outputs. A "TPS Fault code" MAY mean that the TPS is faulty but it might ALSO mean a fault in the wiring between the TPS and the ECU and perhaps even a fault in the ECU itself.

    This is why relying on fault codes alone for diagnosis frequently results in people wasting their money. Confirming faulty components with an oscilloscope is necessary for an accurate diagnosis (Although even that doesn't always work, for instance if you are dealing with an intermittent fault)

    The fault code is just a guide as to where to start looking. Not a diagnosis in itself. It is the analysis of the fault code that you are paying for when you take your car to a competent workshop.


    Source(s): (Source 30 years, vehicle diagnosis)
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