John MI blk/blk '01

When I start my car (from cold) I notice that my idle is rough and I can feel a slight miss. When it warms up the idle smooths out somewhat but I think I still feel a very light miss. I checked my plugs and they were all clean and none were loose. My concern is that the gap on the plug from number 3 cylinder has opened up...out of spec.

I correctly adjusted the gap and thought my troubles were over. The problem still exists. Any suggestions as to what would cause the plug gap to open? Could the plug be defective or the coil? Perhaps a bad injector? Any suggestions greatly appreciated. I am taking it to the dealer next week.

John

CMiS2K

my plugs were as follows, .39, .40, .40, .40, I have 4400 miles on the car, I re-gapped as owners manual calls for .43 all the way through, my gas mileage has increased and idle is stable. this fixed my problem and the car runs much better now that the ecu has cycled the change.

2kturkey

The plug gap will always increase with age. Each time the plug sparks you wear a little of the electrode away. Regapping the plugs, has always, and always will be, a standard maintenance item.

Having said that, the newer thin electrode plugs are made from tougher metals (e.g. palladium) and do not wear quite so quickly as plugs used to. Due to manufacturing variations it is not unusual to have one plug wear more or less than the others.

BTW, a plug gap variation of 0.03 is well within normal tolerance and I would not expect to notice any difference in performance.

RT

John, were the gaps all correct at some point? Is it possible that plug was always gapped bigger than the rest?

John MI blk/blk '01

Thanks for the responses. RT- Cheap insurance...I make it a habit to check the plug gap and torque every couple of months or so. The gaps have always been right on.

I switched the coil from cylinder 3 to cylinder 2 and will check in a week or so to see if it causes the plug gap in cylinder number 2 to open up. If so, I will replace the coil. What's strange was Friday night the temperature was cooler (around 70 degrees) and the car ran flawlessly.

I have to say that this has been the most tempermental vehicle I have ever owned...but I still love it!

Good news is that it has finally stopped burning oil with this last oil change...I have 17,000 miles!

John