In Reply to: Spark Plug Question. (m) posted by Dinan M3 on October 04, 2000 at 14:27:34:
My car has been running a little rough. I have had the car for a few months now. It has a supercharger, but up until about 2 weeks ago, my motor was as smooth as a sewing machine. Now, when I am stopped I get a low rumble every so often. It shakes the whole car just a little, but noticable. The idle is not rough, I mean the RPM gauge does not move up or down; it is constant. Also, it does this while it is cold, and also after being warmed up and driven (so It's not the normal, cold start rough idle thing).
At first I thought I was low on oil, nope. Then I thought bad gas; got gas at 3 different good gas stations; the same. Then the gas filter, but if it was a gas issue I would suffer from speed performance and that has not changed (It is as fast as the day I got it).
With all this said, I took it to the shop. The mech. says it sound like a spark plug miss fire, from either a bad plug or a bad coil. If it was miss fireing, even a little, wouldn't the RPM gauge show that? I am no mech., but I think the motor might be unbalanced (motor mount?) or something like that... What do you guys think?
The car has 27k miles, coulld the plugs ne to be replaced so soon? Also the coils? Thank you for your input.