if a throttle position sensor (tps) is bad but engine idles, could it knock once fixed?

my car would idle ok but once you press the gas it would die. After having it diagnosed i was told the throttle position sensor was bad, but the mechanic was able to adjust it long enough for it to work but said the engine was knocking very bad when he did that. I can still start the car and it will idle without any knocking until you give it gas it dies. could this be true? or where they just trying to sell me an engine? im thinking of buying the tps since there only around 50 bucks and get it put on, just to see if it fixs it.


UPDATE>>>>>>>>>> im think the tps is bad the real problem though because it was diagnosed by a dealership after taking it to other places that couldnt figure it out and the dealership tested it and stuff so i belive them that its the tps i just dont belive the engine is bad because the car was driven once since its been like this. and it will still drive on its own power when its in drive just cant give it gas thanks to all who have answer so far!!!!

4 Answers

  • 1 decade ago
    Favorite Answer

    the knocking could have happened because the spark tables are based on tp and if the tps was not adjusted correctly the spark advance may be too high at certain engine speeds. if knocking wasnt a problem before the tps went bad there is no reason it would suddenly start to knock if the tps was fixed. got to have the right diagnosis to be sure what to fix and it seems ur guy cant give it to you. take it to another shop

    Source(s): Mechanical Engineer, FSAE engine guy
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  • 1 decade ago

    A TPS is nothing more than a potentiometer, and any of the windings in its sweep area can go bad, most common is at off idle. Knock from the engine should be compensated for by the knock sensor. You may have more than one problem. You may not be reaching closed loop status to allow the other sensors to perform their designed function. Proper diagnosis is the key to a good repair. Good Luck

    Source(s): ASE Master Tech 41 Years
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  • If the TPS is completely bad then adjusting it would not fix it.

    Knocking would not have anything to do with the TPS.

    The guy is trying to rip you off, there is another problem but it can be anything from timing to your fuel system, it would have to be diagnosed to be able to even make a good guess.

    Source(s): Owner of an aftermaket Import shop...
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  • hurdle
    Lv 4
    3 years ago

    If the rpm is below four hundred, perhaps. extra apt to believe it would want to be the idle air administration valve. even as they bypass undesirable the motor stumbles and rpm fluctuates. If the TPI is undesirable the rpm will be to extreme or too low yet at a tender rpm. wish you've got entered the three hundred and sixty 5 days make and style of the motor vehicle in question. A depended on inner most mechanic or broking service of the motor vehicle will be able to inform you which of them one is giving you the issue.

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