Hi. I've got a 2000 Excursion with 36,000 miles on it. It has a slight but noticeable miss at idle. No codes or stored misfire data in the computer. According to the very detailed service history from the original owner, it's never had the plugs replaced. It's not been 100,000 miles, but they are 16 years old. Could this be causing my miss? How about the coils/boots?


Thanks

 

Really, 36000 miles?

Both my excursions had miss issues due to water coming in from center joint of cowl (the plastic piece between windshield and hood).

I siliconed the leak and miss went away after water dried up.

I wouldn't think coils would be bad, but I would put new plugs in, if nothing else just so you can see if any water or rust is in the spark plug holes.

 

Yep. I got it in December with 33,000 on it. One owner truck from Texas. I'll check for water leaking in. Hadn't thought of that. I'm planning to replace the plugs, and I didn't suspect the coils would be bad but it never hurts to ask.

 

Probably the coil boots are ready for replacement.

 

Do I need to use OEM coil boots or are any aftermarket brand sufficient?

 

I've used "Standard" brand boots with great success. They were every so slightly different than the stock ones. I could tell the mold wasn't the same.

But, they've held up well, they've been in my truck for the past 10+ years, and never an issue.

Get some dialectric grease. Put a small amount at the top of the boot where it seals to the COP, and then a small amount around the inside of the tip where it'll seal against the plug.

Doesn't sound like you have a bad coil, especially if you don't notice a miss when it's under load.

Clean the MAF too...