Let me add that if you pull the injectors you will need a tool and replacement seals, here is a procedure 2.0 LNF Engine How to install injector seals (LNF) - Cobalt SS Network

It would seem these Colbalt guys have everything figured out with regards to the LNF R & R of anything. FWIW I did read a post about someone with a LNF that had a miss of some sort and and it turned out to be one of the DI injector seals. I tried to find post again but no joy, it must be an old age thing.

It's a topic on the Scion /Subaru forum, Direct Injector Failure Poll - Scion FR-S Forum | Subaru BRZ Forum | Toyota 86 GT 86 Forum | AS1 Forum - FT86CLUB

 

I'll do the top wires first
Won't be able to work on the lower sensor for a few weeks though.. :S

Read about the injectors. Even if just replaced, new seals are needed and yes, a special tool :S

Well... let's see

 

Well... quick update

Did the top sensor, nothing really changed
3 weeks later soldered the wires of the bottom sensor
Seemed better for a day but the the misfire came back
always cylinder 4 for 2-3 weeks
The other day got a cylinder 3 misfire, and the day after cylinder 1 or 2 I think.
After that only cylinder 4 so fat.

I looked at the intake between cylinder 3 and for with an inspection camera through the brake vacuum line. Doesn't look like there is carbon build up there.

 

Just to drop a note here, have you resolved your miss issues yet?

 

There's probably enough buildup to make it look even. I recently scoped my wifes intake the same way. Even after only 1400 miles on the new engine and turbo there's buildup..way to much. In fact, there's less buildup on the valves from the 150,000 mile 2.2 I just rebuilt. Need a methane injection/5th injector to wash off the valves

 

My issue was the MAF sensor on the intake tube by the airbox. It was coated in oil and dirt from the K&N filter and the other part was the air filter came off of the intake tube. Once I checked that everything was back to normal. Check those since they are easy to do.

 

Have to remember the 2.2 in PFI so it will wash off the back of the valves.

 

Thanks for asking
No, I have not solved it yet.
After my last email, no big changes
I would still get cylinder4 misfire most of the time, not ALL the time, when boost goes over 16psi
CEL would come on and blink, the car would sputter for a few seconds (max boost 10-12psi) until the CEL goes away and like an ON/OFF swith, the full turbo is back and engine is smooth again.

I got another inspection camera and looked ad intake 3 too.. looks the same as 4.
I will post a couple of pictures later

 

Not the best pictures ever... I visually intake on 3 and 4 really looked the same

 

Wow, obviously the pictures tell the story of the LNF PCV system and it's effects on coking/sludge.

I'm sure the intake of mine will look the same. And as Dbeluscak suggests, a 5th inject will go a long way in helping reduce that issue. I believe an effective catch can/separator and the addition of the 5th injector will help a lot. Only time will tell.