Hey guys,

Man, I hope someone has a great idea for me here. I've been fighting a misfire on cyl #2 for over a week now, and have tried everything I can think of. Here's the wrap up:

- Tried swapping coils, misfire didn't follow.
- Tried new plugs, no change.
- Had a smoke test done, identified one leak, patched it. No change.
- Checked compression. All cylinders were around 180, so looking good there.
- Swapped the fuel injector on #2 to #3, misfire didn't follow.

There's also an occasional misfire on 5, but it's very intermittent. (#5 also has a new coilpack and plug).

When I went to do the injector swap, I looked down in the manifold and everything was clean but #2. Inside of #2 was pretty heavy carbon deposits, so obviously there's an issue there.

Btw, the car is a 2001 A6 2.7t with 225,000 miles on it.

Any ideas? Could it be the wiring to the injector or plug? I'd think it might be ICM, but neither of the other cyls on that bank are misfiring.

Would love some help!

Justin

Swap the ICMs and see what happens.

Since you have compression, you are either missing spark or fuel to #2. Just test the injector with a noid light to see if it is getting a pulse signal, then test the #2 plug for spark by pulling the coil out, putting the plug in it and touching the plug base to ground while cranking. One or the other is not happening. As gasser said, the ignition module may be at fault.

@hxgaser - I'm going to give that a try tonight and see if there's a change. I'll definitely update once I figure that out.

Am I right in assuming that if there are carbon deposits in the manifold, it means that fuel is being delivered? If so, it looks like I just need to troubleshoot the spark path.

Quick update:

Swapped the ICMs last night, and the misfire moved to 5, so it looks that's most likely it. Ordered a new ICM from ECS and will put it in the car tomorrow and see how it goes. This *should* solve it.

Think it's worth throwing some SeaFoam in the gas tank to help flush out that carbon buildup in cyl #2 once it's firing again?

I wouldn't worry about it. WOT a few laps around the block and it will be fine. Not to mention that your local law enforcement may want to have a talk with you...

If you really want to then feed it through a vacuum line. That will be more direct hit.

Update:

Installed the new ICM this morning, and it's running as smooth as silk. VAG-COM shows no misfires, so it looks like we're fixed up!

Thanks for all the help here, this forum is priceless.

Justin