I'm helping a friend with their 2004 D2 with the 4.6

Misfire #3

We changed the spark plug and changed all the spark plug wires while installing Extinct's relocation kit.

Still getting Misfire #3

We have a backup coil pack, so I'm hoping that may be it so we don't have to remove the upper intake to swap out a fuel injector.

I've never had a coil pack go bad...what are the signs? ...does just one plug for a single spark plug wire go bad or do they usually all go bad?


Thanks,

 

As it’s a wasted spark system a bad coil would probably affect 2 cylinders, unless there’s a problem between the 2 wire sockets, but I think it’s unlikely. If you have a spare, it’s worth a try. Also, you could swap coils to troubleshoot.

 

The coils are siamesed, so each coil pack has two coils integrated in it and with the wasted spark system each internal coil fires two cylinders. Usually it starts with one breaking down and then it will go down both cylinders. As the firing order is 1-8-4-3-6-5-7-2 three and two are on the same siamese coil. The best way to diagnose the coils is swap left to right (or with it relocated front to rear).

 

I thought you might mention the possibility of one circuit shorting out on the hood.

 

Early report is the swapped out coil pack worked. I gave my friend one of my back up coil packs and they changed it yesterday. They only had about 20 minutes of driving time but the the check engine light did not come on. In the past they were only able to get maybe 1 mile before it came on.

So it looks like a bad coil pack can only affect one plug.

 

Following up on JohnZo's short circuit. The kit came with a piece of rubber with adhesive on one side that fits under the hood insulation. I've had the kit for a couple of years now without the piece of rubber with no short circuits.

 

Glad to hear it worked out.

 

Usually that is only tower 5, tower three is not that close to the hood because the stiffening rib is only over the rear two and even then just barely. By the time you reach tower 3 its like 1 inch clearance to the metal.

 

There is some variation in stackup tolerances between trucks, some have plenty of clearance, some are tight and need some help. Even those it is typically only 5 and 8.