I have a 2000 DII with 91,500 miles throwing error code P0307. Cylinder 7 misfire. I changed the plugs and wires using the suggested Bosch Platinum +4 and Magnecor 8MM. Still getting the misfire code. Could the cause be the coil? Would just 1 of the 4 sections fail or would they all fail? Is there any way to check the coil by it’s self to determine if it’s working? I did remove the plug wire and attached one of the old plugs to it, ground the plug and did see it spark as it should. Any suggestions?


BIG greg

 

Check the spark plug for a crack.
Others have had problems with cracks Bosch +4's.
If you do not see a crack move that plug to another spot and see if the mis fire follows.

 

i would swap the plugs to a NGK iridium,,,,

 

I've had good luck with my Magnecors and Platinum +4. Biggest problem I had is I shut one of the plugs in the drawer of my tool box while installing them and spent an extra hour looking for the plug.

I have heard of cracked plugs causing problems before. Also make sure the plug wire is seated all the way on the plug. I know #7 & #8 on my D1 were a pain to get the wire on all the way.

 

Your coils can go bad, but not likely.
#7 is a common one to have problems with, I have yet to hear of a bad coil, but it could happen. But I doubt it.

 

It's not the plug. I forgot to metion that I switched the plug for another location and the problem stared with cylinder 7.

BIG g

 

WHY ????

 

Greg, did you clear the codes after replacing the wires and plugs, is the engine running rough at an idle?

 

Mike,

Yes I did clear the code after each attempt to correct the problem.

The first thing I did was to change the plugs and wires.
The second thing was switch the plug out.
The third thing was to just ground a plug on the motor to see if I was getting spark and I did.

Greg

 

Carbon can cause a mis fire as can a stuck or chipped valve. If it were mine, I would also check the compression. Past that, possibly a coil, not have fault codes but don't always throw them when failing.