Howdy folks, My 02 Disco II developed an issue the other day while we were out, started running really rough and CE light came on, limped it home and took it to work with me next morning (I work at O'Reilly so I could scan it myself) It ran fine most of the way to work, then started shuddering and running rough again. I scanned it and it brought up codes for random misfire, misfires in cylinders 2,4, and 6, and also a catalyst damaging misfire. I've got 207k miles, tuned her up 4 months ago with new plugs/wires/filters. I'm gonna start with replacing the coil packs cause I get them at a good price and go from there, but I'm also looking for possible other fixes. Normally I'd just haunt the search function, but there are so many misfire threads and I didn't have time to browse them all. Any help is very much appreciated.

 

Most misfires are plug/wire related. Coils also. Viewing under hood in total darkness sometimes reveals arcing in a particular spot. Some misfires are related to coolant in cylinders, so keep an eye out for white smoke out tail pipe after warm up, water in oil (milkshake), extenal water leaks from head gaskets, overheating.

 

Even though you may get good prices, quit guessing. Tell us the exact fault code numbers. Who's wires and plugs did you install and what octane are you burning?

 

P0300 random misfire, p0304 cyl 4 misfire, p0306 cyl 6 misfire, p0308 cyl 8 misfire, also a pai my scanner couldn't place, p1300 and p1319. I used NGK Iridium plugs and Bosch plug wires.

 

Both of those codes are also misfire related.
Did this come on all at once or gradually?
If it were mine, I would do a compression test first to rule out low compression misfires from warn out cam lobes and lifter or burned valves. At your mileage either of those can be an issue.

 

1319 is misfire detected when fuel is low
1300 is misfires in quantity and level that can damage CATS

BTW, these are all in your copy of the RAVE, and Adobe reader has good search function. They show up on page 333 and 334. Your mpg will stink until they are cleared up (closed loop fueling may not happen).

 

It came on all at once while we were in town. Check engine light came on and it started missing pretty bad. Then it stopped missing for a few minutes, then started again. It was on and off missig that way all weekend till my mechanic replaced the coil pack. Now it seems to be running alright and light hasnt come back on yet after running all day.