Thought I'd start with you guys on this one since I can't find a past post that applies. I have an intermittant misfire on my '02 Sport Trac 4.0. It started about 3 years ago when it would only misfire once about 3 or 4 times a year that I would actually notice. It only happens warm, at idle, and in drive at a stop light. The frequency of single misfires has increased over the past year to about 2 or 3 times a week. There is never more than 1 misfire and some weeks it's fine all week. I use it mostly as a commuter. It has 50k on the odo. I refuse to take it to the Ford stealer for fear of the inevitable "Sorry, it didn't do it in the shop and the computer didn't show anything. That'll be $95." I'd like to nip this in the bud before I get stranded. I'm not a regular poster so please help with terms like "COPs", which I still haven't found the meaning for.

 

I would start by pulling the codes to see what they reveal. There may be a code stored even if the CEL is out. Most autozones will pull them for free. You could also consider replacing the plugs, wires, air filter, and fuel filter.

 

I didn't consider the wires because of the low miles but they are getting old. But plugs last for 100k, right? Guess I'll look into them too. In the past I have replaced Motorcraft plugs with Autolite since it used to be owned by Ford anyway. Side by side they are identical except for the name. Wouldn't surprise me if they both come from the Fram plant. Fuel filter is unchanged but the air filter is yearly. Even without pulling the codes it seems that it's time to tune-up.

 

If you are going to replace the wires, I'd do the plugs as well. Half the battle is getting to the plug which you need to do anyway to do the wires. With the price of gas, and since you have some sort of problem, I'd do both. You will find it easiest to get to the plugs through the wheel wells.

 

Yeah, plugs and wires together are a given in my book. At least I don't have a cap and rotor like my Ranger. Thanks for the advice on the plug through the wheel well thing. Think I'll stick with the Motorcraft stuff. Don't want to upset the computer.