maaliish

I never paid THAT much attention to the misfire logging in VAG, but after my sparkplug change my car has been somewhat sluggish and so I went into VAG to hunt for problems. I noticed that I was getting misfires and misfire count would go up to 1-2 then clear, then go up again and so on. No errors are thrown though. Upon closer examination, I noticed that cyl 2 was usually the cause, allthough other cyls would throw a misfire also from time to time. I thought that cyl2 coil pack was bad and last night I swapped it with one from cyl 3 to see if most of the misfires move. That wasn't the case so now I'm pretty sure that coil packs are not an issue, atleast not the main one. Upon monitoring the knock sensor voltages, I found that voltage on cyl1 and cyl2 was usually higher than cyl3 and cyl4. Cyl2 had the highest voltage which was also noticable at idle (which is when most misfires occur) and even more evident at higher RPM.

Plugs are stock NGKs and when I was installing them, I noticed that they where all undergapped. This surprised me because NGK states that they come gapped from factory. I re-gapped all the plugs to 0.32 but now I wonder if that was a mistake on my behalf. The plugs I pulled from the car had the right color to them, but where all overgapped, which I thought was normal for a used plug.

Right now I'm leaning towards pulling the plugs and checking the gaps again, but I don't see how I could have messed up the plugs since I tripple checked the gaps prior to putting them in.

Any ideas?

TTschwing

Seen a few of those lately with frayed wires under the insulation jacket... You can buy the harness (VW part I believe), but it needs to be spliced into the main engine harness as it does not attach with a plug...<ul><li><a href="https://forums.audiworld.com/tt/msgs/1419073.phtml">More here from andrewTT..</a></li></ul>

Scenic Driver

I would put them back in to see if the car returned to the way it was before the sparkplug change. If not, then it's probably a coil pack harness like Steve said.

maaliish

ouch...looks like fun :-(

maaliish

I'll give that a shot, that harness replacement looks like a PITA. Thanks.

MaxHedrm

Mine was a connection to the controller for the fuel injection.

maaliish

where should I look for that? Are symptoms very similar?

mobsTTa

You'd notice it, Insulation is split in a number of places. You'll be able to see the wire. So if you can't it's probably not the harness. Even with mine that was split in numerous places on each sub harness leading to the coilpack, the missing was occuring only when weather was damp and then it was temporary until car warmed up. No Cel noted at least at this stage

maaliish

I'm still not 100% sure if thats the case, but so far thats the way I see it.

I'll look at the harness closer when I swap back the plugs.