New throttle position sensor?
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HT4100 4.1, 4.5, 4.9 Discussion, New throttle position sensor? in Cadillac Engine Technical Discussion; Ok I have a 93 Cadillac Eldorado sports coupe with the 4.9 and if you put the car in either ...
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    Chicano-Mexicano's Avatar
    Chicano-Mexicano is offline Cadillac Owners Fanatic
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    New throttle position sensor?

    Ok I have a 93 Cadillac Eldorado sports coupe with the 4.9 and if you put the car in either neutral or park and rev the engine it stumbles down to 500 rpm the jumps back to 1000 but the odd thing is it only does it in park or neutral the car runs great and accelerates flawlessly other wise . I was thinking it could be my throttle position sensor going (it is 15 years old) but I would appreciate any help.

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    behind-bars is offline Cadillac Owners Connoisseur
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    Re: New throttle position sensor?

    Quote Originally Posted by Chicano-Mexicano View Post
    Ok I have a 93 Cadillac Eldorado sports coupe with the 4.9 and if you put the car in either neutral or park and rev the engine it stumbles down to 500 rpm the jumps back to 1000 but the odd thing is it only does it in park or neutral the car runs great and accelerates flawlessly other wise . I was thinking it could be my throttle position sensor going (it is 15 years old) but I would appreciate any help.
    Any codes? When I broke my TPS it seemed to idle just fine, but acceleration was horrible and the shifts were all off. It could be the TPS in your case, but could be other stuff aswell.

    Does it do it all the time, or only when hot/cold?

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    Chicano-Mexicano's Avatar
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    Re: New throttle position sensor?

    The car has not given me any messages on the HUD (so I'm guessing no codes but I'll check) and it does it all the time no mater outside or engine temp but only when it idles as I said the car takes of like a beast when you matt the pedal.

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    behind-bars is offline Cadillac Owners Connoisseur
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    Re: New throttle position sensor?

    If it does it all the time then i doubt its the egr like i was thinking, I suppose you could replace the TPS since its pretty easy to do and not to expensive.

    I would go ahead and check codes like you mentioned then go from their, maybe someone else has a idea of what it could be.

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    kdcing is offline Cadillac Owners Fanatic
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    Re: New throttle position sensor?

    To be sure, test the TPS before replacing it. Get into the PCM DATA? portion of the diagnostics. PD01 will display the TPS angle....with the gas pedal at idle position, the TPS angle should be around 2-4...at WOT it is at a high value around 70-80 (I forget exactly where it should be). The critical item is that the angle that is displayed should move smoothly with the amount that you press on the gas pedal....if the display moves smoothly, then the TPS is likely good....if the displayed value jumps around (or doesn't move at all), then the TPS is likely bad (or its wiring is likely bad).

    Pittsburg yesterday, The Mets today....who's next?!?!

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    carnut is offline Cadillac Owners Master
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    Re: New throttle position sensor?

    Dont rev it in park!! I dont think you have a problem. Check codes and erase any history codes if they appear. Report back if any current codes are present.

  8. #7
    Chicano-Mexicano's Avatar
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    Re: New throttle position sensor?

    Quote Originally Posted by carnut View Post
    Dont rev it in park!! I dont think you have a problem. Check codes and erase any history codes if they appear. Report back if any current codes are present.
    What about Neutral?

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    carnut is offline Cadillac Owners Master
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    Re: New throttle position sensor?

    Please understand that these newer computer controlled engines rely on signals from the transmission and speedometer to supply fuel and timing signals. Most computers do not control either when out of gear because theres no need. So revving it out of gear is not monitored nor controlled. Once the throttle is released, the computer reads the throttle angle and then corrects the engine speed.

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