2004 Jeep Cherokee Spark Plugs keep going bad


Engine Performance problem
2004 Jeep Cherokee 6 cyl Two Wheel Drive Automatic 85000 miles

I have a 2004 jeep Cherokee with about 85k miles on it. I did a tune up on it a few months back, replaced the normal spark plugs pvc valve, air filter, fuel filter and so on. Everything was great for about 2k miles (about 2 months). I was on the free way driving from San Diego to Tucson az and was about 4 hours into the trip, when the check engine light came on, the car started running rough and maintaining 65mph was no longer an option. The light started flashing so I pulled over. I waited a few mins and started driving again. Everything was good until I hit 40mph. Once above 40 the car would start shaking and would run rough, like it was miss-firing. I stopped and had the jeep towed to a shop, where they looked at it, pulled the codes and said it had a random multiple miss-fire. They pulled the plugs and said a couple of them were fowled. They went ahead and replaced all the plugs again. Everything has been fine until today ( a month after they replaced the plugs). The car is having the same symptoms, (running very rough, hard to maintain above 40mph and the check engine light is flashing). I had the work done in Tucson so I cant drive it back there since I live in San Diego. So I am wondering what is causing the spark plugs to keep going bad, (im assuming its the same problem, since the symptoms are the exact same). I am unable to pull the plugs and look at them right now wsince im not with the car. Thanks for your help

Do you
have the same problem?
Sunday, April 18th, 2010 AT 12:37 PM

1 Reply


Hi there,

Thank you for the donation,

We do need to be able to inspect the condition of the spark plug as what we see will give us a good indication as to where the problem may lie, but first thoughts are that you either have a faulty injector and the plug is becoming fuel fouled, a low compression problem or a ignition issue, I would have these items inspected first.

Mark (mhpautos)

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Sunday, April 18th, 2010 AT 6:39 PM

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