I have an '03 Disco II with 98,000 Miles, I have a P0300, P0308 misfire code. It idles fine but is missing terribly at 2k RPM.
I changed Plug wires to Magnecor 8.5MM wires and changed plugs to autolite double platinum. No change same problems. Pulled the new plug from #8 and it was dry with dark soot on it. No noticeable loss of coolant. I don't want to start throwing parts at it, just not sure what direction to take.

 

Have you tried coils? The cheaper eBay ones work fine, and you'll need a new intake gasket, but that would be my bet.

 

Thanks, Is there any easy way to check the coils before replacing?

 

I knew a mechanic who would stick an old timing light to the wires on the effected cylinders to see if they were getting juice, but other than that I dont know of a good way.

By the way, dont drive it AT ALL other than if you need to move it around the driveway once or twice, because the unborn fuel from the misfire will melt your cat converters. I killed one like that and had to cut it out sitting beside the 4 lane.

 

You could try swapping a wire, just to see if the problem stays with cylinder 8 or follows the wire, but yeah, you're probably looking at a coil pack. I'd do both, while you're in there.

 

Im having same issues with same year model disco. i used the kingsborne wires and same plugs the op did. Codes are p1000 for cylinders 3-4-6-8.

Youre not alone...

 

I just ordered new coils, will update after I change them this week end.

 

Make sure that the braided ground wire from the engine to the fire wall exists from the driver's side head (USA driver) to the firewall.

Could be a bad ground too.

Check all the wires grounded to the Plenum / intake are all fitted and there is no green gunk on the bolts holding the wires to the plenum or intake.

 

Odds are you have a faking coil, may be a little early but does happen at your mileage.If that is the case, because of the mileage on your engine, replace both coils for balanced voltage to all plugs and don't buy junk coils, they do not provide the higher voltage of a OEM coil.

 

Just changed the coil pack and I have the same issues and codes p0300 & p0308. When I had the upper intake off the port for cyl 8 had dark black residue in it, the others were clean and dry.
It runs fine up to 2k rpm but then starts missing.
This is so frustrating!
Thanks for any help on how to proceed.
-Hart Bordelon
Hammond, LA