[Gregski]

Volumetric Efficiency VE Table Calibration

So now the MAF has failed, but the PCM won't start solely using the VE Table until a failure code is written to the log. So in order to do that we need to go to Engine Diag \ DTCs tab and change the Error Mode on P0103 Mass or Volume Air Flow A Circuit High to MIL on First Error.

This way as soon as the PCM sees the MAF has exceed 100 Hz it will write a P0103 code to the log and acknowledge the MAF has failed and only use the VE Table for airmass calculations.

If we were to leave the Error Mode on MIL on Second Error, we would need to start the truck run it, then turn it off, and start it a second time and hope the code was thrown on the second start.

Now as far as the SES Service Engine Soon light, you can leave that on or you can leave that off it does not effect functionality, it just lights up the check engine light. I prefer not to turn it on because I expect this error, but I may want to see others so I don't want it coming on and me thinking it's just this MAF failure and ignore it.

also very important, in Speed Density mode your PCM only relies on the Low Octane table so you must copy the values from the High Octane table to the Low Octane table while calibrating the VE Table

GM considers 93 Octane high octane (if all you can find is 91 Octane in your neck of the woods, then be sure to run that) hey if you are taking the time to tune your engine, then I assume you are feeding it the good stuff

the High and Low Octane tables can be found under the Engine \ Spark \ Advance section

during the calibration process both tables need to match, afterwards you can change the Low Octane table back to Low Octane values or leave it set same as the High Octane if you promise to always fill your tank with High Octane fuel (once we get to tuning Timing Advance we will check for knock and may reduce the Low Octane table manually by 2 or 4 degrees)