Did you try tightening the plug with a plier? (do it carefully)

That happened to me while doing mine ('03 DII).

 

The instructions here are GREAT & very easy to follow. Actually the wire change out wasn't as bad as I thought it would be. Although I still think who ever put the Coil Pack next to the Firewall should be severely punished.

Side note I also ended up replacing the front O2s same time for some reason after wires & Plugs.

 

Just popped over from Landroversonly.com and must say...well done. I saw how these wires were going to be a pain in the neck and am glad to see someone had some details on how to change them. I hope to do it without busting a few knuckles open and keeping my sanity at the same time.

 

Since you didn't post again, can I assume reseating the wires resolved this issue? I have the exact result after replacing plugs and wires. Mine is a misfire on #4. Had to replace the wires since the one on #4 was faulty and was arching nearly all along the wire. My best guess is that the resistance change from arching fried that terminal on the coil. I ordered a single coil pack from Advance. Very much dreading replacing the pac, wires were difficult enough. But I did it without removing the IM. Here are some things I learned
DO - slide the Secondary Air tubes to the passenger side, and lift out the driver side single tube first. The dual tube passenger end straddles two coolant tubes and it's easy to lift the single tube side up and toward the double and wiggle up and out from there. Replace the same way. DO - lay on your engine from front to rear to access the coils. DO - tighten four accessible valve cover bolts while you have pieces off, they loosen over time. DO - start by removing the neg batt lead. DO - dump debris from the catch "tank" on the bottom of your Mass Air Flow Assembly while off (I had dirt in mine). DO NOT - loose patience or confidence. My first time with a project like this. You'll be proud when you get it done. Spend your saved money on a party after.

Anyone here think I'll have problems replacing one of the two coil pack with a $62.00 aftermarket replacement?

 

Did it! Truck is running great now. The coil pack was the problem. I really wish I was that guy. The one who wants a big truck because I'm small with a complex. Next time I remove the intake Manifold, there is not much room back there to wrench. Couple notes if you try.
Replacing one of the two packs works, short term diagnosis only. If you replace the whole assembly you will need to remove the IM. I was able to take the one I removed out by wiggling it toward the passenger side. Of course the secondary air pipes were off.
1/4 inch drive(small is needed), universal adapter, 2 and 5 inch ext(3 and 5 would have been slightly more comfortable), and an 8 mm slim socket worked for me. All bolts on the coil pack are 8mm. Secondary Air pipe connection to the bracket is 10mm, bracket connects to the engine with 8mm.
I plan on having this great truck for some time, cause I luv it. Could everyone who succeeds at a task post how to and best practice? I will.

 

Hey guys just ran into a problem while installing a new coil set. i need to know what size screw is used to hold it in place.

please help

 

It's 8mm

 

thanks Martisthree, I just finish changing my coil and i did not remove the IM, Its hard but you can inch it out towards the passenger side and got it back in the same way. Regarding the bolt on the coil to the bracket, mine is not 8mm but its a bolt w/ philip screw not flat head screw if that make sense.

 

Dear all, I had a misfortune of hitting an unpainted sharp speed bump last night on my 2001 Disco II, it started running rough, SES light came on flashing. Upon seeing an arch between the coil pack and firewall I established the #4 wire is hanging loose (the second in the lower row). Spent much of the day today laying on the engine trying to get the wire back to no avail... The lack of space plus the other wires in place make me think its an impossible task, without taking half the engine apart. Please share your thoughts, i'm in Outer Banks, have to head back home to DC tomorrow... Is it safe to drive on 7 cylinders? Many thanks in advance!

 

I would not drive like that. Get a long thin screw driver and bend it in kinda a J shape to get at the wire and push it in.
Look under "Write ups" and "How To" at the write up about changing wire without removing the IM, you'll get the idea.