[SOLVED] Cylinder 1 Misfire - P0301 / P0300 Mystery

[Toothbrush]

Originally Posted by Skyline

Well that compression test is NOT a favorable result. Usually, when adding oil does not bring the compression up, that means the leak is through a valve. This is better confirmed with a leak down test. When you add shop air to the cylinder through an adapter into the suspect cylinder, you can see where the air comes out; oil fill cap, tailpipe, or intake. I could see a scenario where a valve guide seal was bad for so long that the carbon build up is now preventing a valve from completely closing.

Second/new gauge + leak down test is the next 'to-do'. I'll post those results (maybe early next week) once done.

Originally Posted by Skyline

Was this car exhibiting the classic signs of bad valve guide seals? (Punch the gas after idling a few minutes and get a big cloud of smoke out the exhaust; but otherwise running more or less normally.

Yep, I didn't wait very long to do the valve seals once the smoke started (maybe a couple of weeks, after heavy research). No lights up to that point, and a couple of codes that I fixed. One for coolant, which was a rotted fitting for the upper radiator hose and one caused by a bad seal or crack in the crankcase vent hose (replaced same day). No other codes or Lights.

Originally Posted by Skyline

Assuming it's an valve leak, you might want to get a boroscope into that spark plug hole and see if you can determine what's wrong. If there's heavy carbon build up around the valves, getting that removed might solve this problem. I had previously suggested a way to do that.

The cheap boroscope I have stopped working, so need to pick another one up. Went to use it while I had the valve cover off and no picture. I know for sure the top of the piston is covered.

I've been looking at the kit you suggested and am 95% sure I'm going that route before anything else. I've keep hoping it's a sludge/carbon issue that just needs to get cleaned up.