Misfire problem

[triad]

I changed my plugs and wires about 2000 miles ago and about 2 weeks ago I started to get a misfire in my sixth cylinder causing a SES light (I had Autozone scan it) The next day I got under my car and replaced my spark plug in that cylinder and the SES light went away.
Yesterday I tryed to pass someone and stepped on it and my car felt like it misfired again and the SES light came on AGAIN. Had Autozone scan it again and it was the same code - Cylinder 6 Misfire.

Other than a Plug and a Wire being bad what would cause this to happen!?
Timing? Fuel Injector?

[triad]

Anyone?

[RedbirdV6]

Coil Pack!! Get them checked can't remeber which one controls #6 cylinder off the top of my head but you have 3 of them. If I was you I would just replace all 3 at the same time and save yourself trouble down the road :cool:

[black98V6]

it's tough to test a coil pack.. the best way I know is to get one from somewhere with a rather liberal return policy.. try it out and if that isn't the problem bring it back in a day or 2.. had the same problem about 3 weeks ago.. and low and behold after changing plugs and swapping the #5 wire(this was shown as the misfiring cylinder) all was well again..

or you can just buy one.. it's not necessarily a bad idea to have a good one lying around.. luckily I did when mine died suddenly.. oah btw.. this may have NO bearing whatsoever on your problem but when mine went it went all at once.. I mean i was driving and it was like someone hit a switch.. and suddenly it was missing constantly..

[ July 19, 2002: Message edited by: black98V6 ]</p>

[triad]

What is the coil pack? Is that the thing on the engine were the plug wires plug in on the top?

[rockotman]

Yeah - the coil packs (there are three of them on the 3800) are at the top of the engine. Wires run from the packs to the plugs.

You can also test the coil pack in question by swapping around the wires on the coil in question. On the top of the engine, look for the coil with a 6 on it next to one of the wires. The other wire on this coil will have a 3 next to it. Swap these connections at the coil - don't worryThe plugs fire at the same time, even though one cylinder is in compression mode, and the other is in exhaust mode) If the problem is a weak winding in the coil, the problem will move to the #3 cylinder.

If it doesn't (you still get a misfire on 6), then I would suspect the wire. The #6 cyinder on the 3800 is a pain in the butt to get at, if the wires are no the type with a 90 degree boot at the plug end (factory original), they can rub against the manifold heat shield, and eventually you'll get arcing and sparking at the top of the boot. I know you indicate that the wires aren't that old, but I had one go bad after only about 8 months. And it was on #6, because of the heat shield.

Another possibility is a clogged fuel filter. Since #6 (and #5) cylinders are at the far end of the fuel rail, any low fuel pressure due to a clogged filter will make itself evident on these cylinders first.

Another possibility is a clogged injector. If you use crappy fuel, or haven't run any injector cleaner through the system in a while, it might be worth a try. If you really like a challenge, you can pull the injectors and get them tested. But now your getting into a lot of work and expense.

I would swap the wires at the coil pack first, and if you stil get a misfire on 6, then check the plug end of that wire for heat cracks and evidence of arcing.

[ July 19, 2002: Message edited by: rockotman ]</p>

[triad]

So swap them at the coil not underneath the engine?

Leave the 3rd boot on the sixth spark plug and the 6th boot on the 3rd Spark plug?

[rockotman]

Yup!

If you can see the plug boot on six, inspect it real carefully too.

[triad]

I can jack my car up just enough to see it

What am I looking for exactly

[rockotman]

Cracks, splits, any part of the insulation rubbed through or melted.

The best way to inspect it is to pull it off and look at it closely.

The jacket should be soft and pliable. If it is hard and brittle, it probably is damaged.

If you see any signs of what looks like a white or gray residue, that is a tell-tale sign that the jacket is not insulating properly and that the spark is sometimes jumping out there instead of through the plug (which can happen under heavy load, such as stepping on it or going up hill).

[hockeyman]

I posted a problem solver just like this awhile back about the #6 spark plug wire for my 96 camaro 3.8. The wire sits right on the intake manifold and burns the outside of the wire causing it to arc on the intake manifold. I had the same problem you described a few years back, and after giving it to GM two times and three spark plug changes, I finally put new wires on and my problems went away. The key is, when you put the wires going from the coil packs to the passenger side of the engine, put some header wrap around the wires so they dont burn on the intake manifold. If you don't have header wrap, find a way to mount the wires so they aren't resting on the manifold, about 1" or higher above is good.
Good luck,
Marc.

[rockotman]

<blockquote>quote:</font><hr>Originally posted by hockeyman:
I posted a problem solver just like this awhile back about the #6 spark plug wire for my 96 camaro 3.8. The wire sits right on the intake manifold and burns the outside of the wire causing it to arc on the intake manifold.<hr></blockquote>Had the same thing happen on my son's 97 3.8. #6 was the culprit there, too.

[Infernal]

On my friends 2000 3800 it was a clogged cat.

When he romped on it on the highway by the time he got up to around 75 or 80 he got a constant cyl 6 misfire due to too much back pressure.

The dealership replaced the cat. Misfire gone.

[Joe Wallace]

When my 97 started mis firing I changed plugs, wires,coil pack etc... Culprit was the
O2 ( Oxygen Sensor ) I have had my car 1 year and it has failed twice. One I paid for the other the dealership replaced because it was still under warranty. Cost me $480.00 parts and labor.

Hope this helps

[Guardsman]

Double check to make sure that the plug boot is on the plug right. I was having the same problem, the only problem was that the wire wasn't all the way on the plug. The location of the boot makes it a PITA to put on, as everybody knows, and if you're not really, really, really careful (as I found out), you may knock it off as you're pulling your hand out from putting it on.
Also, another way to check the coil (this is from the dealership) is to pull both of the wires off of the coil, and turn the engine on for a second, and if it makes a good arc between the posts, it's good (You will want to have somebody else to either observe or turn the key, so you don't have to have the engine on for more than a second).