MSS54 with 116k miles.
I have a cold start misfire issue where cyl 3 would misfire every morning, but if I allowed the car to warm up and go into closed loop and then turn it off and back on again the misfire would disappear and it would run fine for the rest of the day.
While trying to track down the misfire issue I noticed a small amount of oil on the coil and a large amount of oil on the spark plug threads of cyl 3.
My first thought was valve cover gasket/tube seals so I ordered the kit. But while doing the job I had a closer look at the design on the spark plug tubes. They are one piece that protrudes out of the top of the valve cover, so the tube seals don't seem to be there to prevent oil from entering the tube. Instead it seems they prevent the oil from exiting out of the top of the valve cover which isn't an issue for me. I went ahead and finished the job anyway.
My next thought was maybe it was getting past the piston rings. So I did a compression test and have between 172 and 176 PSI on all cylinders which seems to be in spec. I also did a leak down test with a cheap tester. It can only provide 15 PSI but it past none the less. I then skipped the tester and just provided 90PSI to each cylinder. I could hear hissing in crank case through the oil filler cap, but cyl 3 sounded just the same as the rest of the cylinders. I figure since the rings don't seal 100% that a little hissing is normal. Couldn't detect hissing from intake or exhaust.
I installed new spark plugs and did some other maintenance (valve adjustment, IAC and throttle body cleaning, new MAF) and the cold start misfire went away for 4 days. But today the misfire returned
Pulled the spark plug from cyl 3 and sure enough there is oil on the threads again. Not nearly as much as the first time, but the plugs are only 4 days old.
Other than spilling oil down the tube, what else could cause it? The only thing I can think of is valve seals.
Or maybe it's possible the misfire is completely unrelated to the oil on the plug, and that the misfire is actually causing the oil to accumulate somehow?
Any idea?
I have a cold start misfire issue where cyl 3 would misfire every morning, but if I allowed the car to warm up and go into closed loop and then turn it off and back on again the misfire would disappear and it would run fine for the rest of the day.
While trying to track down the misfire issue I noticed a small amount of oil on the coil and a large amount of oil on the spark plug threads of cyl 3.
My first thought was valve cover gasket/tube seals so I ordered the kit. But while doing the job I had a closer look at the design on the spark plug tubes. They are one piece that protrudes out of the top of the valve cover, so the tube seals don't seem to be there to prevent oil from entering the tube. Instead it seems they prevent the oil from exiting out of the top of the valve cover which isn't an issue for me. I went ahead and finished the job anyway.
My next thought was maybe it was getting past the piston rings. So I did a compression test and have between 172 and 176 PSI on all cylinders which seems to be in spec. I also did a leak down test with a cheap tester. It can only provide 15 PSI but it past none the less. I then skipped the tester and just provided 90PSI to each cylinder. I could hear hissing in crank case through the oil filler cap, but cyl 3 sounded just the same as the rest of the cylinders. I figure since the rings don't seal 100% that a little hissing is normal. Couldn't detect hissing from intake or exhaust.
I installed new spark plugs and did some other maintenance (valve adjustment, IAC and throttle body cleaning, new MAF) and the cold start misfire went away for 4 days. But today the misfire returned
Pulled the spark plug from cyl 3 and sure enough there is oil on the threads again. Not nearly as much as the first time, but the plugs are only 4 days old.
Other than spilling oil down the tube, what else could cause it? The only thing I can think of is valve seals.
Or maybe it's possible the misfire is completely unrelated to the oil on the plug, and that the misfire is actually causing the oil to accumulate somehow?
Any idea?
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