I have a 2003 MCS with about 91k. I recently started having misfire issues (originally Cyl. 4). After searching around, I decided to try to replace the spark plugs (start small, right?), but I’m running into a problem removing the plug wire from the down tube. The Bently manual says to pull up, gently turning form side to side, and it should come right out. I tried that to no avail. I actually pulled on the thing as hard as I could without it budging. This is the case with all four plug wires. I’m going to resort to trying to cut them out (I’ve ordered a new set of wires and a new coil pack), but wanted to know if anyone else has run into this issue, and whether or not there is any “gotcha’s” with cutting the rubber out of the down tube?

Thanks in advance.

 

Sounds like it just got baked on a bit....they should be replaced if the rubber is that bad anyway.....be sure to install you plugs into the head cool, and use a tourqe wrench!!

 

Yes, attempt to change plugs and wires with a cold engine. Heat expansion can make for tighter clearances. As for the coil pack, after I did a boatload of research, stick with the stock one (unless you still have misfires). If the connections are dark, just hit them with a brass brush. Jan from RMW swears by using stock coils.

 

Thanks for the info. The coil pack I ordered is a new OEM. I wanted to have it on hand in case the plug and wire change didn't do the trick. I'll wait a few hours after driving to let the head cool down and give it another go this weekend.

 

I would also run some SEA-FOAM through the motor.....if the misfires are due to carbon build-up from combustion products, this should do the trick too.
When you put the new coil on, be careful not to tighten it too much....or you may crack the cover it attaches to.
Plugs....if you are running a pulley should be 1 step cooler (same as JCW)...and changed as often as JCW, which is about every 30,000 miles.
Good Luck...I hope it is nothing mechanical...if this basic stuff does not fix it, the next step IMO is a compression check...to ensure the problem is not mechanical...unfortunately common, since many people run these cars on fuel that is too low of an octane.....91 is the min in the US, 93 strongly suggested since with 91, the timing is running slightly retarded in most cases!!

 

Good to hear about the coil pack. On the plugs... The Bentley manual says NGK BKR6 is stock. However, both my '02 and '06 MCS' had BKR5 plugs in them from the factory. When I had the pulley, CAI, and tune in my '02 MCS, it was upgraded to BKR7 plugs. These seem to be a sweet spot for performance.

 

Thanks for the tips. I'll run some SEA-FOAM through it as well. I don't have a history on the car, I sort of inherited it. It's bone stock. I've always put 93 in it, but I can't attest to any previous owners.

Hopefully the pack change, plug change, and SEA-FOAM rids me of this issue.

 

It looks like the wire change would have done the trick. Everything is replaced now, new coil pack, wires, & plugs. Took it for a spin around the block with no misfire issues at all. Hopefully it stays that way!

Thanks for the input.