I was logging a couple of runs today to figure out what needs fixing on my car. There's definitely a boost leak in there, and I'll fix it ASAP. However, I was also wondering about the MAF numbers I saw. From an article in the Audizine forum:

So what should numbers be like on a stock car that hasn't been chipped? My MAF numbers progress linearly from 24.5g/s @ 2000rpm to 116.5g/s @ 6000rpm.

 

Hasn't ANYONE taken MAF readings on a stock car?

 

I have been suspecting my MAF may be on the fritz but I'm not sure yet. I checked the values at idle and they were 3-4 g/s; about 10 at 2500 RPM. Mine is a V6 though and I would imagine it would pull more air. I was going to log on the way into work but got lazy. I'll check it tomorrow and see what the log shows.

 

I did finally get some answers on another forum. Apparently the numbers I've recorded are normal. From what I understand, if I divide the g/s value by 0.8, I end up with an approximate amount of crank horsepower that the engine is putting out at that time. So in my case:

116.5 / 0.8 = 145.6hp @ 6000rpm

This makes sense considering I'm missing about 6psi of boost on my AWM engine, which explains why I'd be short about 25hp. If everything was running as expected, I *should* be seeing about 134g/s or so.

Knowing whether my MAF is accurate helps me to determine whether I should be looking for a boost leak or some other problem (like a big exhaust restriction). If there was a boost leak, I'd probably see the full g/s reading (or higher) since the MAF measures air pre-boost. Now I'm leaning towards a clogged-up cat. Not terribly surprising at 228,000 miles.

 

time for a down pipe

 

I've got a 3" high flow cat sitting in the garage and waiting to go on I was gonna wait until after my upcoming provincial inspection to install it so that it doesn't draw visual attention. Meanwhile, I guess I'll get my ECM flashed so that damn P0420 stops popping up (which would also cause me to fail inspection).