hans j

Have a car at work that we got a used engine for (his had severe rod knock) and after all said and done, I get that code.

I have boost tested and smoked the intake, checked wastegate lines, logged and am finding the N75 appears to act normal but MAF seems to read high (at least higher then mine).

ECU is from VAST and has GIAC written on it, gutted pre-cats and exhaust and Hitachi MAF conversion. I checked reference voltage today at the MAF connection and everything checked out.

With the MAF plugged in, it has an intermittent stutter, nearly dies and goes into limp mode. MAF unplugged, car runs awesome. No boost spikes and very solid.

I am thinking about swapping N75's as that seems to be what STFA says but looking for some other ideas. I don't want to think too hard when I can be thinking about snowboarding about the two feet of snow that fell in the last two days

nyet

post logs of req vs actual boost.

hans j

let a small piece of foam into the CAI, allowing it to get stuck on the MAF and create serious driveability problems

nyet

P1557 is a MAP problem, not MAF if your boost is fine...

hans j

screwed up with part of the MAF blocked. Sometimes I would see the MAF pull over 315g/s (at 4500 feet above sea level), a little high for a stage 2 plus car here.

So it is possible sometimes the MAF was reading low with actual and requested boost met, yet at a lower load then the computer expects, creating a positive deviation.

The car would run perfect with the MAF unplugged as well, definitely not the case if it had a bad MAP or actually over boosting.

edit: And an intermittent MAF code also led me to believe it was related, but the boost code was always there when driving with the MAF plugged in. It was a hard lesson to learn, I hate getting peoples sloppy seconds! "Here, I put this engine in and now it doesn't run right. Make it run."