o.k. cars been running real rich at idle. black sut coming from tail pipes. i have been monitoring all the sensors and values with your scanmaster write up. everything looks normal, the bl's go down to 108 saying it's rich, i have a feeling it's the mass air sensor. this reading is 6-7 fluctuation at idle which is normal. next i get a mac mentor scanner from a friend and monitor with it everything is perfect except the maf and it is 10.4! which i believe would make it run rich. why does the scanmaster say onething and the mentor scanner say another? they both take their values out of the pcm? any help or direction would be greatly appreciated thanks Brad

 

Were both MAF readings taken with the engine fully warmed up, coolant temp normal, and idle speed the same in both cases?

 

yes they were taken simultaneously scanner then switched of and read scanmaster then turned off scanmaster and rechecked scanner temp of 176 and iac at 40

 

Did you have both scanners connected simultaneously? I would be surprised if either of them worked if that's the case, because there is some 2-way communication involved. If you read 6-7gps with the ScanMaster, disconnected it and connected the Mentor, and got 10.4gps, and nothing changed in between... RPM in particular, I have no idea why you would get different readings.

The PCM is reading the frequency output of the MAF sensor, then converting it to GPS using the calibration table in the PCM. Can't see where it would be interpreted differently by different scanners???