I have a 2001 5.4 that misfires under a load and from all the searches on this forum I have troubleshot my problem down to a bad coil on plug. The problem is, I don't get a check engine light so I can't tell which cyllinder it is, so I can just buy one at $67 and fix it. If you don't get the light, is there a good way to find out which one it is without spending $100 at the dealer to run a check? I was thinking of pulling the plugs to see which one looks black if that works.

BTW, I would just spend $200 and change them all if I could, but Troyer Performance has been on backorder for their 8-pack since Aug., so that is out of the question since it's getting worse every day.

Thanks in advance everone for the help!

 

If you do a search on the net, you will be able to find a site with the resistance values of the coils(sorry, but I can't remember which one, just plug some info into a search engine and something should come up), and if you are capable with a multi-meter or know somebody that is, you should be able to determine which one is bad. Otherwise, you will have to chase them individually around, i.e: pulling one and replace it with your new one, assessing any difference in perfomance, and if there is no change, then you move on to the next coil. I had a coil go south on my wife's V10 work van, along with dealer installed plugs that were inproperly gapped, and an air intake system that was loose(dealer again),but I narrowed the hesitation problem down to a coil. I didn't know which one either, so I bought eight slightly used ones of ebay for $200.00 Canadian, swapped in the back eight on the V10(front two are easiest to change if I had to), and it was like driving a new van. I know I've rambled on, but, they can be bench tested.

 

Found it! I went and bought a coill and just started changing it out one cyllinder at a time. #6 was the culprit. Thanks for the help.

 

I had a bad miss and the code showed misfire cylinder #1. I checked the resistance on the coil pack and it was right in the middle of the specs. Replaced it anyway and the miss was gone. Can something else go out on the coil and still keep the resistance correctly?

 

Found this website:

http://www.aa1car.com/library/2004/us20406.htm

An interesting exchange of information concerning ignition systems, coils, COP, and troubleshooting tools. Hope it helps the next guy!

Curt

 

Another way to tell is an exhaust port that runs cooler than the rest.