Misfire and backfire

[jah4ha]

2002 Windstar codes P0302 and P0306.

New plugs and wires. Plug five (front center) had heavy carbon buildup. Is this caused by clogged EGR ports? Revving at high rpm it stumbles and what sounds like backfiring.

Any suggestions appreciated

[12Ounce]

One easy thing to get "off the list" is the EGR system. Find the EGR valve, lift and plug the vacuum control line that connects to the EGR valve. Go for a drive. Does it run better? If so, you have EGR issues. (Ignore the Check Engine light that you will get... it will go away when everything runs properly again.)

[jah4ha]

No there was no difference with the EGR unplaugged.
With engine running I unplugged the injector wires one by one. Only number 6 had no change. I can feel it clicking and I can smell unburn fuel. Could the coil bank be the probem?

[12Ounce]

Yep. But why not remove that plug, hook it up again ... letting the plug base rest against engine metal (ground). Let the engine idle and see if the plug sparks.

[jah4ha]

Checked. No spark to no.6 and no.2
Could the coil pack serve most of the sparkplugs and not the other?

[12Ounce]

Not sure how your model year is laid out ... but on my '99, the coil pack is a package of three separate coils, each coil serving two plugs. And, yes, a single coil in the pack is likely to fail all by itself.

[jah4ha]

Replaced the coil bank and that did it.

Thanks 12ounce for your input.

Just a note to anyone that might change the coil bank.
I searched but initially got wrong info on the wiring positions for the coil bank.
Standing in front of the car:
The back of the engine (windshield side) is from left to right is 1 - 2 - 3
and the front is 5 - 6 - 4.