Cylinder 3 misfire-at wits end

[Alishia655]

Ok. So a little backstory. I bought my 97 Expedition 4.6L almost 5 years ago. It has been my baby. This was the best vehicle I have ever owned. About a year ago, my brother in law needed a larger vehicle to carry his kids in since he now has custody. We gave him my expedition.

Last week, he changed the spark plugs and wires because it was running rough. He put in NGK plugs and cheapo wires. Then the CEL started blinking (Raw fuel in the cat.) Cut to now-we drove 200+ miles to him and another 200+ to get the expy home. Cylinder 3 and 8 were blowing the plug wires off the plug. After replacing all plugs with motocraft and putting "premium" wires on, cylinder 3 has NO fire but neither blow off the wire. Changed out the coil packs with a brand new ones, same problem.

I haven't tested the compression yet, but either than that I have no idea what the problem could be.

Anyone have any ideas? I appreciate any advise! My husband doesn't want to put any more money into it as we now have a 2011 f150 with a hefty monthly payment.

 

[Bedrck47]

I doubt that your problem is the coil packs Could have been a plug or the wire but since you have changed them. The attached link will give you some useful information and a better understanding of the systems.
You may also want to check the fuel injectors

First you need to understand how the 2 coil packs work.
Click on the link below

http://troubleshootmyvehicle.com/ford/4.6L-5.4L/index-of-articles-1

Then read the article

How To Test The 2 Coil Packs (Ford 4.6L V8)

 

[stamp11127]

How did you determine that #3 isn't firing?

 

[Alishia655]

My scanner lets me watch each cylinder. It had 70,000 misses in a very short time. (I'm not sure of the exact amount of time) I pulled the plug out and it's still clean. Can also smell the raw fuel that isn't being burned.

 

[stamp11127]

All the plug wires need to be routed through the oem wire holders to avoid the spark jumping to ground. Inspect the wire for evidence of firing through the wire insulation, it is usually white in color.
Can you read wiring diagrams?

 

[Alishia655]

I can, but I'm not great at it. My brother in law didn't route the wires the same way as factory or through the clips. I'll check those tomorrow. Thank you.

 

[rjdelp7]

Disconnect the fuel injector on bad cylinder, if you plan on driving it or you will ruin your catalytic converters. It may be already to late.