wrx580

I'll check out the repair manual today and try to figure out where that one is. Anything is worth a shot at this point.

Zaphodb17

It sounds like you have a secondary ignition short to ground. If you're hearing a "click" every time the misfire occurs, you need to double check that somewhere between the coil pack and the spark plug the current is shorting to ground. For instance, on my 2.8L 30-valve, the coil packs are mounted on the top front of the plenum and each has a plug wire to individual spark plugs. Anywhere in the run to the plug there can be a burn through to ground. It looks like you have cylinders 4 and 2 misfires, so I'd start with a visual on those. Even if you have individual coil packs above each spark plug, isn't there still a 3 or 4 inch wire and boot sticking down to the plug? Look for a small "dusty" looking mark on the side. Good luck.

wrx580

I'll certainly give this a shot. However, wouldn't this occur all the time, and not be intermittent? I have the 2.8 30V as well, with the packs all mounted together at the front of the plenum.

Airbag

if you hear clicks I agree , sounds like escaping spark ... when it is doing it go out at night and pop the hood , you will see it for sure if it is escaping spark ..

wrx580

Good idea. I'll pull off the engine covers and do this when it gets dark tonight. It sounds like it's coming from the driver side of the engine. I guess if I don't see anything, I should assume it's happening inside the head/near the spark plug?

Airbag

could be but you should still see it .. Sounds like you could just have weak leads

wrx580

Okay, I finally had a chance to check for sparking tonight.

The car had been sitting for a couple days. When I went out and started it up, it ran fine. I took it for a drive to warm it up. It ran fine for the first minute or two, then slowly began to get worse and worse. After about 7-8 minutes I brought it back to the house, parked it and popped the hood.

Here's a strange thing. I put the parking brake on and put the car in Reverse to put the engine under load and induce the misfire. Initially, it was "stumbling", but I didn't hear any electrical clicking. I also didn't see any obvious sparks under the hood. After letting it run a while longer, it finally started making a clicking noise (still coming from the left side of the engine). I pulled up the plastic cover on the cylinder bank, and sure enough, there was a big fat spark coming out of the spark plug wire every time the engine misfired. It was right at the point that the wire makes a 90 degree turn into the engine block.

Now at least I know one thing to try. It bothers me that I didn't hear the sparking noise during the initial stumbling. Could it be that there is another factor at play? I guess all I know to do is replace that plug wire and see what happens. Don't even want to know what that's going to cost...

edit: I forgot to mention that I did see some faint, flickering sparks around the ignition coil. Is this normal, or could that be a symptom of a malfunctioning coil?

Airbag

You should see no sprak anywhere .. that is what the spark plug is for ..if one lead is failing you can bet the others are degreaded too as they have been in the car the same length of tim. gaet yourself a COMPLETE set of leads, and plugs. use dielectric grease on the inside of the boot to make sure they slide on and seat correctly.

wrx580

Will do. I guess I'll start with a full set of spark plug wires, and if that doesn't do it, I might be replacing the ignition coil as well.

Does anyone have any insight into why this problem seems to vary depending on how hot the engine is? Expansion of the rubber surrounding the wires? It seems strange...

Johann2.7t

Im still betting it has something to do with either of the coolant switches, at least mine is. I have a small leak back there and I think the coolant switch isnt fully submerged.

Did you track misfires with vag com?