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Thread: Rough at idle

  1. #1
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    Rough at idle

    Hey Guys,
    I've been noticing that the car runs rough at idle, or when I stop at a light. So i've already replacing the fuel filter, no change. I have cleaned the air filter and MAF sensor, no change. I noticed inside the intake that it was really dirty inside, so I cleaned it out really good. I have replacing the spark plugs, no change. When the check engine light comes on, tells me that cylinder 8 is misfiring, and then I get random misfires. Next I replaced the coil pack in cylinder 8, and of course no change.
    I decided to change my driving habits . I took the car down the shore for three days, the car ran great, I DID NOT beat the snot out of the car. I Noticed it ran great. On way home I stopped over to gas. I opened the car up, ran it alittle hard. After running it hard I stopped at a light, there it goes, it was running rough, the check engine came up.
    I'm thinking, should I replace the Injectors now? What do you guys think?
    Wondering if the injectors are all gunked up, like inside the intake.

  2. #2
    Join Date
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    SEAFOAM IT!!!!
    No Marauder

  3. #3
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    it sounds like a bad coil pack

    it sounds like a bad coil pack,

    it can be hard to find the right one,

    cylinder 8 does run hotter due to head water flow

    good luck, hope its not a toasted head
    Sold on 1/16/2012
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  4. #4
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    Quote Originally Posted by Marauderjack View Post
    SEAFOAM IT!!!!
    Two or three times. With a FULL bottle, not 1/2 like it says. Let it sit 10-15 min. Your neighbors may call the FD, but the car will thank you for it.
    Magindat: (majin-dat) Imagine That.
    2013 Ford Taurus SHO

    Lemonade - living with Fruit Punch - in Blackmobile's Garage...
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  5. #5
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    I don't know how much your catalytic converter will thank you for blowing tons of oil residue through it
    Steve H., Charles County, MD www.carfap.com
    1994 Lincoln Town Car. 98-02 front brakes, P71 steering and sway bars, Eaton swap build underway using TorkTech 4.6 2v intake kit.
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  6. #6
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    I had a problem with rough idle. Car ran fine while driving but idled rough and even quit a few times. I cleaned the MAF and replaced the fuel filter. I even replaced the Cats. My problem ended up being a vacuum leak! I couldn't hear it until the day I found it (right after replacing the Cats.) Mine developed a hole where the line from the PCV valve connected to the intake. Of course, they don't sell just that piece so it was $38 for the whole assembly from PCV valve to the piece I needed.
    http://www.mercurymarauder.net/forums/image.php?type=sigpic&userid=3139&dateline=1166318856
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    Larry W. Blum, Jr.
    Walnut Hill, FL.

  7. #7
    Quote Originally Posted by mtenderenda View Post
    Hey Guys,
    I've been noticing that the car runs rough at idle, or when I stop at a light. So i've already replacing the fuel filter, no change. I have cleaned the air filter and MAF sensor, no change. I noticed inside the intake that it was really dirty inside, so I cleaned it out really good. I have replacing the spark plugs, no change. When the check engine light comes on, tells me that cylinder 8 is misfiring, and then I get random misfires. Next I replaced the coil pack in cylinder 8, and of course no change.
    I decided to change my driving habits . I took the car down the shore for three days, the car ran great, I DID NOT beat the snot out of the car. I Noticed it ran great. On way home I stopped over to gas. I opened the car up, ran it alittle hard. After running it hard I stopped at a light, there it goes, it was running rough, the check engine came up.
    I'm thinking, should I replace the Injectors now? What do you guys think?
    Wondering if the injectors are all gunked up, like inside the intake.

    First of all why would you change the injectors with out first determing the DTC code?, if its missing it could be a bad plug bad coil or broke piston, first of all determine what the DTC code is, if that leads you no where, then pull the injector plugs off one at a time replacing the plug each time to determine what cylinder is missing, then check that plug and run a compression check.

  8. #8
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    Hey thanks for the update. I should check the PVC valve. Yeah just like you, the car runs great when I am driving, once I stop and sit at a light or in traffic, its rough. I'll look at my PVC Valve and that line too

  9. #9
    I have the same problem, but no CEL. I have stalled a couple of times.
    Last edited by Aren Jay; 06-03-2008 at 01:32 PM.

  10. #10
    Quote Originally Posted by Diabolical1 CC View Post
    I have the same problem, but no CEL. I have stalled a couple of times.
    Same here, no CEL, but kinda "loopy" at idle and sometimes its a little hard to start, sounds like it wants to die. Runs like a champ though, no mis-fire or anything like that. Ive swapped out the fuel filter and no help. Anything else to check?
    03 Black Marauder - Garage Queen/Weekend Pimpmobile

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  11. #11
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    Just picked up a Marauder last week and it has the same symptoms. No lights thrown just a rough idle.

  12. #12
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    Are you guys all selling the same car to each other?
    Steve H., Charles County, MD www.carfap.com
    1994 Lincoln Town Car. 98-02 front brakes, P71 steering and sway bars, Eaton swap build underway using TorkTech 4.6 2v intake kit.
    2011 Infiniti M37x
    2004 F250, v10 6 speed manual. ex-US Forest Service truck
    2000 BMW M5
    1976 Jeep DJ5 (postal)

  13. #13
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    Quote Originally Posted by VicsEvilBrother View Post
    I don't know how much your catalytic converter will thank you for blowing tons of oil residue through it
    What's this Catalytic Converter you speak of?
    Magindat: (majin-dat) Imagine That.
    2013 Ford Taurus SHO

    Lemonade - living with Fruit Punch - in Blackmobile's Garage...
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    World's first BLOW THRU ProCharged Marauder - Reinhart Tuned

    #1649
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  14. #14
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    It's probly a vac leak. These motors HATE un-metered air. When idling, the proportion of unmetered air in the leak is higher than at higher RPM's. It wreaks havoc with closed loop operation since the ECU tries to correct the unknown mixture via O2 sensor input.
    Magindat: (majin-dat) Imagine That.
    2013 Ford Taurus SHO

    Lemonade - living with Fruit Punch - in Blackmobile's Garage...
    FIT Procharger Kit #31 - 3.7 pulley - 9 PSI
    World's first BLOW THRU ProCharged Marauder - Reinhart Tuned

    #1649
    boi

  15. #15
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    The avatar is PERFECT

    Darkside's avatar is crazy perfect. I love it. I showed it to my Honda driving friend. He turned red.

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