Misfiring problem just before boost kicks-in, bad MAF or O2?

[JDMSIL80]

There's some violent misfiring and random cut-out in low rpm especially when the car is cold, and its getting worse each day. Ive already replaced the coil packs and new plugs, still does the same thing. But once I hit boost and rev pass 3000 rpm, the power is smooth without misfire. Pretty good chance the MAF sensor might be going at this point, since they one I got is used and wasn't in perfect condition. Im also wondering if it could be the 02 sensor, what do you think?

[r34 gtr]

its gotta have something to do with the ecu's open/closed loop control. i would check the 02 and maf, but it could also be something like a coolant temp sensor. try swapping the ecu out to if you can, its worth a shot.

- tim

[JDMSIL80]

Think i found the problem.

I recently installed Megan turbo exhaust and took out the temperature sensor since the exhaust doesn't have the O2 bung for it. It hasn't been welded back in the exhaust yet.

Is it neccesary to put it back in? I assume yes because it might be screwing up fuel delivery.

its gotta have something to do with the ecu's open/closed loop control. i would check the 02 and maf, but it could also be something like a coolant temp sensor. try swapping the ecu out to if you can, its worth a shot.

- tim