Took the car for a drive yesterday and it started running like crap. Obviously it was running on 3 cyl. Last year I had a burnt exhaust valve in #3 and I was hoping this was not the case again.

As I pulled plug wires to locate the culprit cylinder, it was #3 again. I pulled the plugs and #3 plug was heavily coated with black carbon. The rest of the plugs were brownish so they seem to be working well.

Did a compression check (cold) and this was the result #1 - 152, #2 - 155, #3 - 152 and #4 - 150. all looked good.
Ohmed the wires and they were fine. Cleaned the plugs and regapped, car works great.

My question is, why does #3 always seem to be running rich? I am probably due for a fuel regulator change but wouldn't this effect all the plugs?
When I did the head last year I also installed rebuilt, flow matched injectors.

I am running Bosch WR7DC+ plugs. Should I go with an NGK BPR6ES, which I believe is one step hotter?

 

If you only have one cylinder fouling - then it is not an issue with spark-plug heat range...
Is the plug fuel fouling or oil fouling?
What injectors are you using?

 

My car is stock except for a LBE and I am running stock injectors rebuilt and flow matched by Markus Blazak.

I have attached a couple of pics. The single is of #3 (looks lke oil fouling to me) and the other is all four, with from left to right, #4, #3, #2, #1.

Often times when I bring the car to full boost I can see black smoke from the exhaust. Never blue, just black. i was thinking FPR.

 

Yep, #3 looks oil fouled. It looks like mine did when I broke a piston ring-land...

 

If that were the case would I still get the compression numbers I am getting? Also, do you think a hotter plug will help?

 

A hotter plug is not the correct answer... You need to find the reason why that cylinder is oil-fouling.
It is possible to get good compression with a bad oil-ring.

 

Makes sense. If it is limited to one cylinder than it has to be something with that particular one. Other than the oil-ring what else could it be?

 

A very bad off valve guide/seal.

 

I do have a couple of FPRs for you to try if you want to eliminate a variable, though it doesn't sound as though that's the cause.

 

Definitely oil fouled, stem seals or rings. Do the stems first as there easiest and cheapest. It's the 'While your in there' thats a killer. This is fairly deep with a head removal, so make a plan then triple your budget. Next year you'll be happy. You have looked in the J-boot right?

 

When I had the burned exhaust valve in #3 last year (oil fouling could have caused the carbon build up that led to the burned valve), I purchased a completely rebuilt turbo head from Markus Blaszak. Valve seals should be fine. Usually you get some blue smoke at startup as well when the valve seals go because of the oil leaking by. I don't have blue smoke at any time. Just black when accelerating hard.
I have had the J-boot off, and yes there is some misting of oil along with a little puddling here and there in the intercooler pipes. I think my turbo seals are a little leaky. It is the original turbo and the car has 223,000 km (138,000 miles) on it.
Looks like a bad oil ring then. Are there any motor decarbonizing methods that could help that?