Thread: Rpms on the highway?????

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  1. #1 Rpms on the highway????? 
    SE Level Member nickdemio's Avatar
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    When im on the highway my rpms will go up & down between 1000 and 2000 even if my foot stays on the gas...does anybody know what could cause this?? It just started today while driving to work and has never happened before.
    2001 GP GT
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  2. #2 Re: Rpms on the highway????? 
    GrandPrix Junkie
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    So the tach is bouncing, but how does the car run? Any different or it runs fine while its doing this?
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  3. #3 Re: Rpms on the highway????? 
    SE Level Member nickdemio's Avatar
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    Well, i only feel the difference when it jumps up...the car kinda accelerates & then when the tach jumps down the speed just evens out to the amount of pressure im putting on the gas pedal..guess u can say it evens out. Not a big difference tho...car dosent chug or anything.
    2001 GP GT
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  4. #4 Re: Rpms on the highway????? 
    Killa Bee Scottydoggs's Avatar
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    are the rps, actually going up and down or is it just the tach, or is it more like you are slipping out of overdrive and into 3 rd gear?

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, gen 5 N* 3.0 pulley, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW
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  5. #5 Re: Rpms on the highway????? 
    SE Level Member nickdemio's Avatar
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    Jus the tach i guess..cuz i dont feel a big difference in the way the engine is performing..cuz it should with the rpms jumping between 1000 to 2500!
    2001 GP GT
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  6. #6 Re: Rpms on the highway????? 
    GrandPrix Junkie
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    I wonder if the CPS is starting to go? Usually the tach just bottoms out before the engine shuts down, but I guess an intermittent signal would do this.
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  7. #7 Re: Rpms on the highway????? 
    SLP, GTP or call it MUT! thunder71173's Avatar
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    It is the common fluctuating rpm condition that is caused by one of the sulenoids on the tranny. Mine has had the problem since I purchased it. Check tep's site
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  8. #8 Re: Rpms on the highway????? 
    SE Level Member nickdemio's Avatar
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    Is that something i need to worry about & get fixed? Is it a easy fix..like how much would it cost to fix? and wouldnt it throw a code?
    2001 GP GT
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  9. #9 Re: Rpms on the highway????? 
    GrandPrix Junkie PurpleGuy's Avatar
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    mine does it...never throws a code. However you should be able to feel it jerking. If you can't and it's fluctuating a whole 1500 rpms then I think it would point more toward a CPS. Does your tach ever just die?
    2001 Regal GS, PLOG, 3" DP, 1.9's/L76 springs. 21* of timing on a 3.4"
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  10. #10 Re: Rpms on the highway????? 
    SE Level Member nickdemio's Avatar
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    Tach never dies & today was the 1st and only time it has done this.
    2001 GP GT
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