2004 Deville very rough idle in morning
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Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, 2004 Deville very rough idle in morning in Past Cadillac Vehicle Discussion; Hello about 2 weeks ago I started my car in the morning and the idle was very rough, the car ...
  1. #1
    bluesteve1 is offline Cadillac Owners Member
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    2004 Deville very rough idle in morning

    Hello about 2 weeks ago I started my car in the morning and the idle was very rough, the car was shaking. I ended up driving another car that day, because of the shaking. I went home that night and started my car and the shaking had stopped. The car ran fine until 3 days ago, when I started it in the morning and the same thing happened. I let it run and sit for a while and pressed on the gas a few times and it went away. it's happened every morning(3) since. I smells like it's running rich while it's sitting there as well, but goes away after it starts running right. there are no check engine lights on and the temp gauge always is below medium. Car has around 96,000 miles and only seems to do it the first start in the morning. Anyone have any idea what the problem is? where should I start?
    thank yall in advance

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    basscatt's Avatar
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    Re: 2004 Deville very rough idle in moring

    check for Diagnostic Trouble Codes -

    if you don't know how - go here and read the ENTIRE post -

    http://www.cadillacforums.com/forums...odes-dtcs.html

    if you have any codes - post them here -
    ALONG WITH THEIR DEFINITIONS -

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    Ranger's Avatar
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    Re: 2004 Deville very rough idle in moring

    If it smells rich I'd check for a leaky FPR.

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    bluesteve1 is offline Cadillac Owners Member
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    Re: 2004 Deville very rough idle in moring

    Quote Originally Posted by Ranger View Post
    If it smells rich I'd check for a leaky FPR.
    Thanks to both of y'all for the replies. I will run the codes tomorrow.

    Ranger, is FPR. Fuel pressure regulator? How can I tell if a leaky FPR is the problem.

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    Ranger's Avatar
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    Re: 2004 Deville very rough idle in moring

    Yup, that's it. Remove the silver beauty cover and locate the FPR on the fuel rail. Pull the vacuum line while at idle and look for any sign of fuel at the nipple. There should be none.

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    bluesteve1 is offline Cadillac Owners Member
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    Re: 2004 Deville very rough idle in moring

    Pulled the codes today and these are the current ones that came up:
    B0429- temperature/mode #3 circuit range/performance
    P0300- engine misfire detected
    U1000- class 2 communication malfunction

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    basscatt's Avatar
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    Re: 2004 Deville very rough idle in moring

    the P0300 is a generic misfire code -
    that is the one area out on-board scanners fall short -
    it won't tell us which cylinder/cylinders are misfiring -
    take the car to AutoZone or any large autoparts store and have them scan for codes -

    P0301 is cylinder #1 - P0305 is cylinder #5 - P0308 is cylinder #8 - etc -

    once you find out which cylinder is misfiring -
    you can check the fuel injector - spark plug - etc

    my guess is that you will have a bad ignition coil -

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    bluesteve1 is offline Cadillac Owners Member
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    Re: 2004 Deville very rough idle in moring

    So more than likely that code is causing the rough idle?
    Also ranger I checked the FPR and there was no leak

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    Re: 2004 Deville very rough idle in moring

    Yes, but before you go any further, when was the TB last cleaned? A dirty TB can cause a rough idle. Probably would not set a P0300 code, but can't hurt to give it a good cleaning first.

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    basscatt's Avatar
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    Re: 2004 Deville very rough idle in moring

    ------------------------------------------------
    So more than likely that code is causing the rough idle?

    well - not exactly -

    something is causing a misfire -

    the misfire was detected and set the code -

    once you find out which cylinder is misfiring - we can help diagnose the cause -

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    Re: 2004 Deville very rough idle in moring

    Something to think about as well: How old are the spark plugs?

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    bluesteve1 is offline Cadillac Owners Member
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    Re: 2004 Deville very rough idle in moring

    I believe I found the problem to the rough idle! I started changing my spark plugs and I did the front 4 just fine. I went to tackle the back ones and I noticed that a hosed seemed loose. I jiggled it a bit and realized it was completly broken at the rubber connector. The part that is broken is under the manifold. What all do I need to do to replace it? Also what is it called and could I pick it up at an autozone or other store? Here are some pics:


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    MoistCabbage's Avatar
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    That's the PCV "dirty air" line elbow. Any appropriately sized rubber elbow will work. Check the "HELP" isle at the parts store.

    You may be able to replace it with some 90 degree pliers (or some other specialty pliers), or you could remove the manifold.

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    PineyJustice is offline Cadillac Owners Fanatic
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    Re: 2004 Deville very rough idle in moring

    You should be able to grab it and pull it straight out the front of the manifold, just keep in mind getting it back on that nipple inside the manifold is going to be a PAIN.

    Better off getting a chunk of rubber hose that fits over both the plastic pipe and the PCV valve nipple and not taking it out while you do it.

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    Re: 2004 Deville very rough idle in moring

    The only place you would find that particular PCV pipe/hose/connector is Cadillac - either from Chris in Parts at Rippy Cadillac over there >>>, www.gmpartsgiant.com, or maybe (maybe) special order at a local dealer.

    IF you want to remove the intake manifold and replace the entire pipe you can use a length of proper sized fuel hose from any parts store - that pipe is subject to manifold vacuum working against the fixed PCV orifice in the right (rear) cam cover, so you need fuel hose which has a reinforcing braid in the cover.

    The intake manifold is dry - no coolant involved - tutorials down in Discussions; Cadillac Tech Tips. Pictures in my albums.

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