Yes. I figured you'd be back.

A clue.

Start here.

 

Appreciate the help, but I’m not much of a mechanic. What could foul up a PCV?

I bought the tool to adjust the valves and a new valve cover gasket. I figure I’ll try that since it’s something I want to learn how to do anyhow.

if it helps here’s my spark plugs from cylinder 1 and 2.

 

Plug on the right looks like it's running a little leaner than the one on the left. Could just be the lighting, the whiter the ash, the hotter/leaner it's running

 

Blowby and carbon deposits building up over time in the PCV valve, slowing down it's ability to open and close.

 

Do a leakdown and compression test to determine whether combustion is leaking into the crankcase.

A valve adjustment is a good idea also.

 

Sounds good, I'll start with the valve adjustment and hope for the best. If I have compression issues, then it will have to be taken to a real mechanic.

 

+1 on compression and leakdown. I had an intermittent misfire that occurred mostly when the engine was hot, turned off for a few minutes, and then re-started. The car ran fine and didn't have any power loss. Idle did sound more subaru like than it should have. The second time the CEL happened under those circumstances, I checked compression and cylinder 4 was pretty low. I had a shop leakdown it and was leaking a lot through the exhaust valves. I had burnt exhaust valves on Cyl. 4. I had the head rebuilt and got my compression back.

 

I took a look at jwong’s car tonight. Did a valve adjustment and it was within spec. Proceeded to do a compression test to validate the head was indeed good and it held 265 across the board.

Figured I would try and reproduce the issue and see what I could find with the live data over OBD2. Short term fuel trim at idle seemed to be consistently at 10-15%, closed loop. I need to validate what is normal on my working car but when the issue surfaced fuel trims would linearly increase to almost 50% and the idle would get really rough.

Apparently the O2 sensors and ignition coils are new so I’m leaning towards an injector issue, especially since the pending code seems to show up on cylinder 1. The car does not break up under load or exhibit issues on open loop mode so doesn’t seem to be MAP related.

Edit: Long term fuel trim on my AP1 was -3% which is more in line with what I would expect.

 

If swapping injectors moves the pending code that is likely the culprit. Thanks for your regulator vid btw doing that now.

 

Figure I'd update this thread, we swapped out all injectors, the car ran great for a few days (similar to when I replaced the PCV), but now the misfire is worse than before, it even misfires at cold idle when then rpms is high. I've bought a new Walbro fuel pump and we'll throw that at the car next.

Also, I read that bad O2 sensor can cause this, but I replaced both O2 sensors about a year ago with the corresponding Denso part. So I think its unlikely its that.