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revs seem funny?

This is a discussion on revs seem funny? within the General Help forums, part of the LSx Technical Help Section category; today i noticed (of course right before storage tomorrow) that my car's RPMs seem to float higher once i put ...

  1. #1
    Lead Foot mammoth713's Avatar
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    revs seem funny?

    today i noticed (of course right before storage tomorrow) that my car's RPMs seem to float higher once i put in the clutch and go to shift into the next gear... and my foots not on the gas at all... and it just floats a little higher... just enough for me to notice

    actually, i first noticed it when i put on the catback and it seemed to just breath better...


    is this normal or is it a throttle position sensor or something?

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    Miss October toi tyme's Avatar
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    my car sits at a higher RPM when in neutral than in park or drive.... is this what you mean, i have an auto.

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    Slow'er'Ass Mr. Luos's Avatar
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    How many miles ago did you install the catback?

    How much higher does it 'float?'
    If you are coming to a stop and have it in neutral, does the car normally sit at regular idle? Or does it hang around 1300-1500 RPM?
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    The instructions with our catback system directed that the battery be disconnected in order to force the PCM to "re-learn" with the lower restriction exhaust. This may be your issue -- but it could also easily be a vacuum leak or sensor problem as well.

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    Senior Member casperss's Avatar
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    Quote Originally Posted by Mr. Luos View Post
    How many miles ago did you install the catback?

    How much higher does it 'float?'
    If you are coming to a stop and have it in neutral, does the car normally sit at regular idle? Or does it hang around 1300-1500 RPM?
    Hey thats what mine does. I thought it was normal, or am I wrong?

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    Lead Foot mammoth713's Avatar
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    installed the catback around 1k miles ago? maybe a little over 1k?

    but yeah i deffinately noticed it started "floating" lets say it goes up around 300 rpms tops once i put the clutch in to shift to the next gear... my friend and i noticed it right when we test drove it after the install but figured it was cuz the engine was "breathing" better... but i am not sure..? its not like it happens on every shift but it is prevalent enough so i noticed it.

    i dont remember the directions saying anything about that but you may be right... i never fully read directions hahaha. so by disconnecting the battery the PCM recalibrates the intake/exhaust senors etc...?

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    Slow'er'Ass Mr. Luos's Avatar
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    Quote Originally Posted by mammoth713 View Post
    i dont remember the directions saying anything about that but you may be right... i never fully read directions hahaha. so by disconnecting the battery the PCM recalibrates the intake/exhaust senors etc...?
    No.

    The PCM will relearn without disconnecting it.
    It could just be a change in the air. Or a dirty MAF.

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    Quote Originally Posted by Mr. Luos View Post
    No.

    The PCM will relearn without disconnecting it.
    It could just be a change in the air. Or a dirty MAF.

    Agreed. The PCM will always be changing things based on sensor feedback. Disconnecting the battery forces it to do so on initial start up. Usually, the engine rpm will start out a little low and it will hunt for idle. Took our car under 2 minutes to get back to where it was supposed to be.

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    Lead Foot mammoth713's Avatar
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    hmm well the car is in storage begining today... now i'm driving my 93 lesabre and hating this. ahhaah

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    Moderator Cutlass's Avatar
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    Reminds me a little of this thread...
    high idle only when moving
    BTW my car just starting doing this too. Wonder if its the cold weather? I'm gonna hook up the scan tool and check the IAC counts, TP sensor, and Fuel trims to see if I can come up with something.

  11. #11
    Lead Foot mammoth713's Avatar
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    eh my car does that too but this is different

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