Rough, loping idle...

Discussion in 'SVT Forum' started by Kilgore Trout, Nov 29, 2006.

  1. Kilgore Trout Fried or Broiled ?

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    My Cobra idles rough.

    So far I have tried:
    -seafoam
    -changed plugs
    -cleaned MAF
    -reset PCM

    Is it normal for there to be a bit of roughness in the idle?

    Other things I am planning to try are:
    -new fuel filter
    -new x-pipe because I think my cats are clogged

    But maybe the lope is just normal for the engine??? :scratch:
    Kilgore Trout, Nov 29, 2006
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  2. timeless2 Vi Veri Veni Versum Vicus Vici

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    It's not throwing any codes, right?

    Why would your cats be clogged with the low mileage you have?
    timeless2, Nov 29, 2006
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  3. Uncle Meat Banned

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    These engines do not lope with the stock cams. Should purr like a kitten. Haven't heard of problems with the stock cats getting clogged. This rough idle happens warm or cold at idle (approximately 750RPM's)?

    U.M.
    Uncle Meat, Nov 29, 2006
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  4. Kilgore Trout Fried or Broiled ?

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    Clogged cats seems to be a pretty common issue people post about for 03s...

    The check engine light is not on.

    It does it when warm.
    Kilgore Trout, Nov 29, 2006
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  5. Uncle Meat Banned

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    I've rarely read about clogged stock cats on a STOCK '03. Seems if they were clogged though the down stream O2's would be throwing a code.

    U.M.
    Uncle Meat, Nov 29, 2006
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  6. Kilgore Trout Fried or Broiled ?

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    What do you think is causing my idle issue?
    Kilgore Trout, Nov 29, 2006
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  7. 68torinogt Hey guys, guess what--I have a bi-pass!!!

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    [IMG]
    68torinogt, Nov 29, 2006
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  8. STRTRENEGADE354 New Member

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    What did you use to clean the maf?
    And what plugs and what gap do you have them at.
    STRTRENEGADE354, Nov 29, 2006
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  9. Kilgore Trout Fried or Broiled ?

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    I used quick drying electrical contact cleaner spray to clean MAF.

    I installed Motorcraft AGSF-12FM1 gapped at .035
    Kilgore Trout, Nov 29, 2006
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  10. Kilgore Trout Fried or Broiled ?

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    You know this is a tech forum right? Keep that kind of "crap" in talk... :notnice:
    Kilgore Trout, Nov 29, 2006
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  11. Kilgore Trout Fried or Broiled ?

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    Well, I just recleaned the MAF and also cleaned the IAC plus I again reset the PCM.

    The idle still sucks :(

    Next up is a fuel filter, if that does not correct it I have a feeling it is gonna be something expensive to fix... $$$
    Kilgore Trout, Nov 30, 2006
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  12. Uncle Meat Banned

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    If you just recet the PCM, make sure you give the car at least a half-dozen drive cycles and see if it clears up. Did it idle rough prior to repacing the plugs?

    U.M.
    Uncle Meat, Nov 30, 2006
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  13. Kilgore Trout Fried or Broiled ?

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    Yes, the idle is exactly the same as it was before I started doing things to attempt to correct it. Nothing I have done has had any effect on the rough idle.

    However, driving in to work this morning in the cold rain with the a/c on the idle was much smoother. Perhaps the fuel trims are re-learning to smooth it out. I will keep a close eye on it for the next few days.
    Kilgore Trout, Nov 30, 2006
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  14. Uncle Meat Banned

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    I say give it a few more drive cycles before taking it in for professional help. :D

    U.M.
    Uncle Meat, Nov 30, 2006
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  15. Kilgore Trout Fried or Broiled ?

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    Yeah, until I get my tax return professional help is not really an option... Christmas is killing me this year :(

    Thanks for the advice sir :flag:
    Kilgore Trout, Nov 30, 2006
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  16. 68torinogt Hey guys, guess what--I have a bi-pass!!!

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    im sorry,


    i suggest putting a scanner on it and pull off sensor info,

    we have a snap-on scanner and it gives tons of good helpful info.
    68torinogt, Nov 30, 2006
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  17. midlifecrisis99cobra Founding Member

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    My 99 has done the same thing since day 1. Slightly rough idle at about 750-800 rpm when warm. Idles smoothly about 850-900 when cold. Gets better for about 15 minutes after changing plugs then goes back to same old deal.

    I occasionally wonder about an injector/coil issue. Doesn't seem to be generating any codes.
    midlifecrisis99cobra, Nov 30, 2006
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