Misfire confusion

gthphotography

Well-known member
Aug 27, 2008
312
3
chicago
www.greghanrahan.com
So, I have been having issues with cylinder 1 misfiring on and off for a very long time, like years. The most recent version has really got me puzzled.
Here goes:
1 month ago I noticed P0301 with steady MIL and flashing MIL. Normally the issue is the end cap on the spark plug unscrews itself and/or the spark plug itself comes loose, or the misfire corrects itself and the MIL turns off. Normally I retighten the plug and cap and clear the codes and everything is fine for a while. This time was the same, and I then drove 800 miles round trip with no issues. In the last few weeks though, the P0301 is constant. I plugged in my Nanocom and watched the misfire screen, and basically cylinder 1 did not fire for about 3 days. Then it became intermittent. Then it actually cleared the MIL itself and ran great for about 36 hours. Now the constant misfire is back. I did a compression test and it reads 0 for cylinder 1.
My question: What the hell is going on in that cylinder and what should I do?
Also: it's bleeding oil from the spark port and the plug is covered in oil.

any help much appreciated.
 

mearstrae

Well-known member
Mar 15, 2017
106
5
Pennsylvania
Sounds like a stuck or bent valve and/or missing valve seal. Could also be a problem in the cylinder itself, broken rings for example. I'd say the head has to come off and then things will become more clear.
 

pdxrovermech

Well-known member
Jul 3, 2009
1,726
28
Portland, OR
if you're sure it not a bad plug wire and you've already eliminated the plug itself then I would have to agree its likely a valve issue