Misfire after plug+wire change

[BillyCobin]

Alright, I did a plug and wire change on my 96 3.8 After I finnished I ran AutoTap to make sure it was running smoothly. I had a Gauge window open with the Current Misfire #1-#6 so I could see on which cylinder, if any, there was a problem.

At idle I would get a misfire every 10 seconds or so on one or two cylinders, usually the same ones. I reved it up a bit and got no misfires. I drove around the block, and while accelerating or at a constant speed, I wouldn't get any misfires. But when I idled at stop signs and in the drive way I would get a few misfires. Unfortunatly I did not run AutoTap before hand to get a base reading, always and after thought, so I am wondering if a misfiring at idle, but not under load is normal?

Let me add a little, all the wires are firm and snug, triple checked. The wires where lightly greased with dielectric grease. The wires have not melted or been visibly damaged. I can not see a spark arcing when under the car.

The plugs that I put in are Bosch Platnum +4. They have 4 electrodes, and I was told not to gap them. I am wondering if these might be the problem.

[ June 14, 2002: Message edited by: BillyCobin ]</p>

[daWhoady]

misifre at all is not normal. I once didn't put a plug all the way on snug and it gave me a misfire here and there.

[Brian Dieckman]

If you don't get the plug in tight the first time you fire up, the coil might be damaged.

I would check that all the plugs are tight, and I would get rid of those Bosch plugs.

I've had three different kinds of Bosch plugs (including the Platinum +4's) in my car and none of them ran as good as the AC Delco that were in it before.

I have a 95 3.4L, so I didn't get any misfire codes or antyhing, but it would miss once every few seconds on random cylinders. Changed the plugs to AC and problem fixed.

I have no idea why this is the case, but it is in my case.

Good luck.

-Brian

[mailman]

I recently had a misfire situation with the SES light flashing. Had the dealer check and they replaced a bad plug wire (free under their campaign). One week later, got another SES light but steady this time. Took to autozone (free scan check) and they showed a cylinder misfire. Cleared the code and have had no more problems. I gotta believe that GM has a major problem here but is too cheap to own up to it.