Need Help To Eliminate A P0101 Code

[Mike_Vermont]

Hello,

I have a new to me '03 Sierra 2500HD with a 8.1L/Allison and 72,000 miles. Soon after I bought it the P0101 (MAF circuit range/performance problem) started popping up. It has a OEM air cleaner, I have checked for air or vacuum leaks between the MAF and the intake. I have cleaned the MAF with electronics cleaner.

My questions are:

Is there a way to test the MAF to see if it is bad?

Is there a way to test the MAP to see if it is bad?

And there is a check valve on the air box, what is the check valve suppose to do and if it is not working correctly can it cause the P0101?

I have done some searching on this site and the internet and found that a leaking intake manifold could cause the P0101. I am not getting any other codes, like a too lean or too rich code, so I do not think it's the manifold, but has anyone had a P0101 and the problem been the manifold?

 

I want to say this is a great site, I have learned a few things already, this is my first GM truck, and I really like it. My wife and I are almost fighting over who gets to drive it.

 

Thanks alot,

Mike

[Rat4go]

IIRC, that code tends to set when the MAF sensor reads lower than it should based on how much fuel the engine needs to run the right A/F ratio, so looking for Vacuum leaks AFTER the MAF (between the MAF and the intake valves) is the right place to start. Notorious for this is PCV system stuff. If the PCV hose isn't connected to the inlet duct (or intake manifold...it goes to different places on different motors and I don't remember where it goes on the big big block) or if it's not connected to the PCV valve on the rocker cover, you'll set the code, typically at idle where that 'small' vac leak is most significant.

 

Good luck!