I have a 99 Ford Expedition that started running rough, checked the codes because it is showing check engine soon light, shows code for spark plug 4, took wire off put back on and erased the code


Asked by Aug 29, 2015 at 04:51 PM about the Ford Expedition

Question type: Maintenance & Repair

my Ford Expedition is running rough, have replaced fuel filter, air filter, changed the oil. After running a scan it is showing with a P0304 code and when I looked that up it said misfire on number 4. I am fairly broke right now until payday next week and need to make an approximate 200 mile rt trek on Monday. Should I start with just one spark plug to see if that cures the problem? I cant really afford to buy all 8

4 Answers


You have done the troubleshooting, now replace the plug(s), Caution... if this is the 5.4 engine, the plugs are a bi..h. search YouTube for ford 5.4 replace sparkplugs and pay attention.


lol thank you oldtimer37, its a 4.6 but I am getting someone to replace the plug for me, don't have the tools and right now cant afford to buy them. Thank you so much for the response, I am so thankful to have found this site, you and another person have been so helpful. Made me feel better that it isn't something serious

Bob Beaman

The problem is likely one of the following...spark plug, spark plug boot, coil on plug or a fuel injector. How many miles on this vehicle and how many miles since the plugs were changed?


Bob, about 8 months ago, however, it ran just fine until I got gas at a place that apparently is noted for watering down their gas. Didnt know they watered it down as I had just moved here. Think I will start with the sparkplug and see how it goes from there. I have tried changing out the fuel filter, checked the air filter, changed the oil and when running the codes it came out as the 4th sparkplug misfire

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