Sooo my brother has a 2005 STI and is getting a misfire code on cylinder 2. He has swapped the injector and the coil with different cylinders and it keeps coming back, always on cylinder 2. He says he is also getting really bad gas mileage, and his knock correction is at 1.0, which he says means full retard (lol). Anyway, wondering if anyone has an idea of what else he can check to see if it might be the issue. He cleaned some grounds also, and is going to check the wiring to the #2 coil to make sure nothing obvious is going on, and do a compression check to see if it is low on that cylinder or what. Help if you can, thanks guys.

Does he have an aftermarket intake?

Naw it is bone stock IIRC. he did clean the MAFS though and it didnt help.

something is causing a lean condition which is what that is...bad gas or he's not running premium.

almost any aftermarket intake, downpipe, catback will cause a lean condition, they are tuned as lean as possible from the factory.

have the codes cleared, disconnect the battery pump the brake pedal and use premium year round.

I dont think he has any mods at all, and only uses premium. He lives in California though so you know its 91 only there. But its a new issue and he has had it for 3 years or so (the car). He says it has happened through a few tanks of gas from different places, and he ran some fuel system cleaner through to make sure nothing was clogged. Also tried some octane booster. No help

is it a Cali car?

Mine throws one every once in a while. I just clear it and slide it on.

Not sure if it is a Cali car, I will ask. I think so but I will double check.

knock sensor is bad.. pulling timing.

That makes sense, I will tell him to check it out.

the outback did something similar over a year ago.. and when the knock sensor would pull the timing.. the car felt like i was trying to drive with the brakes dragging.
a knock sensor code never came up.. it was always a misfire code.

also.. tell him to be careful tightening the knock sensor when he installs the new one.. it's like 15 ft/lbs or something like that.

those cars are real bad for blowing rings out too.