Originally Posted By: The_Eric
Don't replace any parts solely on my input, but yes, a MAF sensor can cause the driveability issues and shifting issues.
One guy I do work for has an 02 Tahoe that would shift all sorts of mushy into 3rd (IIRC)- especially when you're hard on the throttle. The few times preceding the fix, I would do something unrelated to the MAF and test drive it and set a code. The first time, I cleaned it and told him to keep an eye on it. The heck of it was that it would never code for the owner. Whenever I did any work to it, it would code. Turns out I drove it hard enough to kick the code for "MAF out of range" Finally convinced him to replace it and BAM! Trans shifted perfectly and no more MAF code.
As a test, you can unhook the MAF. The computer will default to a predetermined value based on engine speed, TPS and MAP. The computer will always have the predetermined value, but the MAF will report back the actual. If the MAF varies too much from the computer's idea, then there is usually a code. But not always.
Yeah, PCMs seem to try too hard to believe a faulty sensor. When I installed the wideband in my '04, I used a factory O2 hole and removed the original O2. I just tied it up out of the way. It would go to about 10:1 AFR at idle on that bank trying to get that O2 to switch before it would give up. There was an audible change in the engine noise when it finally set a code and went to the tables.
