96 Deville high idle.

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Northstar Engines and System Technical Discussion Discussion, 96 Deville high idle. in Cadillac Engine Discussion; Hi everyone. I need some help here. I got the car is idling high. I was able to shut the ...
  1. #1
    skeet83951 is offline Cadillac Owners Member
    Automobile(s): 1997 Cadillac Deville
    Join Date
    Feb 2010

    96 Deville high idle.

    Hi everyone. I need some help here. I got the car is idling high. I was able to shut the engine off, start it up and it would run at 625 650 RPM. Now it seems like when the temparture goes down to 35 degress the idle goes up and wont come down.
    I have replaced the IAC the TPS andcleaned out ever inch of the thottle body by soaking it in cleaner for 2 days and blowing it out with compressed air. Checked every stinking square inch of the top end of the motor for air leaks. I have checked all the eletrical plugs for dirt and moisture. I have had this thing apart 6 times in the last two weeks. I have now dumped over 300 dollars into just parts alone. I spent 4 hours Friday staring into the engine compart not doing anything, just staring trying to figure this thing out. I have spent numberous hours search these threads and forums.
    I cleared all the codes about 1 1/2 months ago, I regularly check to see if any codes pop up. Nothing, not so much as a peep from any codes come up.

    What the hell could this be, is it eletrical, computer, or a devil mouse living in the engine.

    Anybody with suggestions, solutions, recommendation. I cant afford to take it to the dealership (hence all the money has gone into part alone).

    Thanks for any helpp you can give

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  3. #2
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
    Automobile(s): 2002.5 F55 STS, 2004 F150 SuperCab 4x4
    Join Date
    Feb 2006
    MD Eastern Shore

    Re: 96 deville high idle.

    Depending on temperature the normal cold start sequence is: 1200 rpm for maybe 30 seconds to a minute and a half, 900 or so rpm for another minute or so, then to 650. Entirely possible that, in extreme cold, the IAT may hold fast idle for a while longer.

    How much different is your hot idle ?

    (Just saw your identical post up in Deville - - - )

  4. #3
    skeet83951 is offline Cadillac Owners Member
    Automobile(s): 1997 Cadillac Deville
    Join Date
    Feb 2010
    Thread Starter

    Re: 96 deville high idle.

    Sorry for the double post. I went back to find the first post, could find it thinking it didn't go through. I am not sure about the hot Idle spped but, the car is at operating temp. It still running different speeds. once at 200 degrees or even dead cold, the speed is around 1300 jumps from that to 1800 down to 1500 up to 2025. Its really all overthe place. Again I replaced all the obvisiuos parts checked for air leaks. Strange I just cant pinpoint the problem. I drove all day yesterday, temp outside was 40 degrees and no problem. once the dark come and it gets colder, it starts acting up. Like as if the cold may becauseits denser air, causes the idle problem

  5. #4
    magistrate_apeman is offline Cadillac Owners Member
    Automobile(s): 1996 Deville Base
    Join Date
    Sep 2011

    Re: 96 deville high idle.

    Ever discover the problem? I'm going thru the exact same rotten ordeal...

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