View Full Version : Help with misfire!

10-20-2015, 09:02 AM
I daily a 98 A4 1.8t that has forged pistons and stainless valves and a Eurodyne tune running at 20psi. Last week I blew a seal on my turbo and started dumping smoke out the exhaust. I swapped turbos (both were K03's) and then I was having a misfire on cylinder 2. So I pulled the plugs and the one on cylinder 2 was caked with oil and in the worst condition I had ever seen a spark plug. The other cylinders were aged but not as rough as #2. So I replaced all of them and still had a misfire. I swapped coil packs with cylinder 1 but still had the misfire on cylinder 2. All of this took place 600 miles from home and I had to drive home for work on Monday. So, I drove the 600 miles without any issue... well I started leaking gas from injector #1 as the o-ring was bad but I thing that is unrelated... Last night I sea foamed it and that didn't seem to help. I am continuing to drive it because it is the only car I have that runs. The misfire seems to be only when the RPMs are below 2000. The CEL flashes below 2000 rpms. The CEL codes I am pulling are P0302, P1198, P0140, and p1338. Also my boost is being cut at 5 psi so I think the p0302 is causing the limp mode.

What I am thinking... I think the oil that blew out of my blown turbo when into the cylinders and was what cause the plug in cylinder 2 to get destroyed. There was a little bit of oil around the coil pack in the hole for the plug so I think my valve cover gasket is bad. There is also an oil leak coming from the back of the engine but I cant figure out where from, So tonight I am replacing my valve cover gasket. So oil could be leaking into the cylinder and cause the misfire as well. Now I have read that the PCV valve could be bad and cause the added pressure which causes the leak, so I am going to try and figure out if my PCV valve is bad.
I also am going to do a compression test and see if cylinder 2 is bad.

If anyone has experienced a similar thing, or has any knowledge on this whatsoever, PLEASE HELP!

10-21-2015, 05:31 AM
I had an oil leak this weekend. dripping... I have a 2.8
i replaced the PCV components, including clearing a clogged Jet pump thingy
no more oil leak so far, its been 3 days

10-21-2015, 09:34 AM
So you didn't do any gaskets just the PCV stuff?

10-21-2015, 10:48 AM
Thats right.
I was planning on doing all gaskets and seals but after much research it seems blocked PCV system can cause pressure build and leaking.
I believe it is highly recommended to check this prior to replacing gaskets/seals.
Im pretty sure you have the same jet pump/valve deal. The 45 degree portion on mine was clogged. I just drilled into it lightly and the bit popped through the crud pretty easily.

Sorry all my info is for the 2.8 but the idea is the same.



10-22-2015, 09:10 AM
Thanks, I'll look into that as far as the oil leak goes.

I did a compression test last night and have no compression in cylinder 2...