Why Is The Ignition Coil In Cylinder 8 Of My Ford Mustang Gt Going Bad So Quickly/causing My Car To Misfire

Posted in Ignition Systems | Asked on May 14, 2010

I have replaced the ignition coil in cylinder 8 of my 1999 ford mustang gt 4.6l 5 speed/manual 3 times within the last 3 months. The last time i replaced the coil in that cylinder i also changed out all my spark plugs. the car has 100,000 miles on it, and the problem always seems to come back and it rains and then stays…. When i replace the ignition coil in cylinder 8 the car stops misfiring and goes back to normal but when the problem comes back the service engine light blinks and when i accelerate the car stumbles and stutters. According the the owners manual when the SERVICE ENGINE LIGHT BLINKS IT INDICATES A MISFIRE. someone please help, the coil is expensive and advanced auto parts isn’t going to keep replacing it, something is making the coil/car in cylinder 8 do this. I first learned cylinder 8 was the issue by plugging in a scanner which revealed the code for a misfire in that location. The same went for the 2nd time this occurred and I am positive it shall go again when I do it next..
KEN I GUESS U WERE TOO DUMB TO SEE THIS CAR USES COIL ON PLUGS LIKE I BRIEFLY EXPLAINED THE YEAR AND CONFIG ABOVE… THERE IS NO DISTRIBUTOR LET ALONE A CAP OR WIRES… PLEASE DONT ANSWER WHAT YOU HAVE NO IDEA ABOUT..

There are 6 Answers for "Why Is The Ignition Coil In Cylinder 8 Of My Ford Mustang Gt Going Bad So Quickly/causing My Car To Misfire"

  1. J J says:

    Theres a reason our folks used terms like “Found On Road Dead” and “Ford – they circled the problem.”

  2. ididntdoit99 says:

    If you change one coil you should change all of them… The idiots at advanced should have told you that. And check ebay for the coils… way cheaper.

  3. FleetTech says:

    I habe at least 100 4.6 and 5.4 Ford engines in the trucks in our fleet.
    Since 1997 I have never replaced all coils just because one of them is bad. Not necessary and too expensive to do.
    We use coils from Ford, NAPA, Auto Zone and Advance, no problems with any of them.
    Main reason for a coil going bad is either excessive heat- or water getting on it.
    In your case I go with the water as you said it happens after / during a rainstorm. Cold water on a hot coil is asking for a failure.
    Somehow water may be getting on the coil. Maybe the cowl to hood seal is bad or missing. Perhaps you will need to add something to deflect the water away from the engine and coil.
    On ht etrucks some had a leaky heater hose and dripped coolant onto number 4 coil ruining it. The heat gets the last 2 on each bank.
    My son tells me you can get high performance coils as a set of 8 from Summit Racing , check their web site.
    Good luck and hope you can get the problem stopped.

  4. ken k says:

    at that miles you should have replaced all the coils and the wires and dist cap etc/in other words replace the ignitions system

  5. dwayne c says:

    Alright. got a friend who had this same problem with his 03 lightning. he replaced coils like five times. And he washed it one day at the car wash and it did it again. Water was dripping on to the engine between the back of the hood and cowl area. He replaced the hood rubber and it fixed his problem. you could lay some blue shop towels over the engine at the carwash and wash it and then check and see if the towels are wet. this would tell you if thats it.Hope this helps good luck

  6. AmericanMuscle.com says:

    When you experience the misfire – have you tried swapping that coil out to another cylinder to see if the problem follows the cylinder? If it does, then it is a problem with the coil (obviously); however if it doesn’t follow the coil then it could be a problem with the spark plug or the ECU’s coil driver.
    Since you mentioned that it happens most often when it rains it sounds like you may have an intermittent short or bad connection somewhere in the system. You should check to see if you have water/fluid dripping onto any part of the ignition system. Also, to trouble-shoot the problem when it’s not raining you can take a spray bottle full of water and, with the car running, spray down the ignition system to see if you can get it to misfire.

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