Hey folks, recently got a 2000 XJ8L over the summer with 60k miles and its been driving fine until mid month last month. Its been real hot where I live and one of they days I went out I saw the restricted performance message pop up and my car started shaking, not super violently but similar to an idle engine but with a bit more of a bump each time. Sorry if that isn't specific enough as to how far the shaking is but I have more info. The 2nd time I took it out I got check engine lights and have since gotten an OB2 scanner and read the codes:

#1 P0308 Cylinder 8 Misfire Detected
#2 P1314 Misfire Catalyst Damage Fault Bank B
#3 Ignition Coil H Primary Control Circuit/Open

From what I've read I should go replace the the set of ignition coils and see if I still have the issue but I wanted to reach out here as this forum has been useful for finding fuse diagrams and yall are much more experienced with these cars than I am. My scanner can read live data and I took a snapshot while the car was running with the shake see attachments:






Im not the most car savy person but I can follow instructions, what is the right steps I need to take to fix this problem? Im using this car to go to college and I don't have the money to take this into a mechanic without putting it on a credit card or something.

Non critical unrelated problem when I was replacing the fuses to get the cigarette port power again my passenger door no longer auto locks (it used to but I clearly messed something up), I still got a full pack of fuses if anyone knows what fuse is causing that or why id be appreciative.

Thanks.

 

I'm not sure if 1 bad coil would do restricted performance I had burnt coil no codes except engine was not smooth anyway I would disconnect the battery for while that's for the door lock , check if it's the coil or spark plug you can pull the coil while the engine running see if there's sparks or not if no get new coil rock auto have them I think 23$ for aftermarket coil or get used coil pack set from ebay
Also check if there's oil leak around the spark plugs oil leak can cause misfire and lastly clean the MAF with MAF cleaner but first fix the coil issue

 

You can swap the coil position and see if the fault shows at the swapped position

Would have to clean fault history before hand , there may be a cycle requirement before fault shows again like maybe 3 engine starts

There was a coil tester ( Innova 4400 ) in the back room of the O'reily's auto parts stores , call around to make sure the store has one , not all have them and they were being removed

Test coils as they are hot ( hot is where they fail )

Be prepared to run the machine yourself and bring heavy leather gloves

The power switch is on the back ..............................ask me how I know

 

From the codes it sounds like a bad coil on cylinder 8, which is the left rearmost plug (driver's side USA, the be clear). I agree with moving the coil from #8 to #7, which is 1 forward to see if the problem moves with the coil or stays with the plug. Personally I'd be picking up 1 coil and 1 plug to see if it cures the issue and if the cat code goes away. If the cat is saved then I'd be doing all 8 plugs and possibly the other 7 coils so I know when they were all done instead of having one newer than the others.

If you disconnect the battery, make sure the trunk key lock mechanism works before you close the lid, otherwise you're going to have to deal with trying to either energize the car with a charger or maybe drill a hole or something to get the trunk open.