another possibility is...aftermarket, wet filters can coat the hot wire of the maf and put both bank fuel trim askew. they usually do not meet oem filtering standards and let crud get past the filter and onto the the maf sensor. maf sensor cleaner rarely, if ever fixes contaminated maf's. the only cars that I would put one of these filters and cai on are vehicles that do not use a maf. If it uses speed density calculations for fuel trim, there is no maf to contaminate. Cai on newer 2008+ can create false fuel trim dtc.




if it runs with the maf unplugged, does it run better? What does the fuel trim do?

 

This whole project has been a learning experience. I finally got back to it on my day off.
I have discovered I still have a lot to learn expecially about how fuel ratios work.

So this is what I have found.

The truck will run without the maf sensor. It runs pretty ruff when it is cold. Once it goes into CL it seems to level out. However the fuel trims are drastically different while unplugged.

stft B1% -10
ltft B1% 0.8
stft B2% -13.3
ltft B2% 0.8
map(inHG) 10.6