Tuning MAF from 3.5 intake size to 4.0 intake size.

[peadarharmon]

2012 Silverado 2500 HD 6.0 L96 with E78 ecm.

As part of my swap I replaced the factory intake with a 4" OD intake and K&N. The old intake at the MAF was approx 3.7" OD. I'm getting a lean condition ( +25% stft ) on both banks.
The lean condition is caused by the new 4" intake because the lean code disappears when I replace it with the old intake using same MAF.

I could just spend ~ $200 to get a smaller intake + filter but I thought going the HP tuners route would be money better spent.

Has anyone experience configuring the MAF to do the math based on the 4" OD intake vs. the 3.7" OD intake. If can you let me know what's involved or how difficult it is.

I'm trying to avoid the $800 tune but that may not be possible.

thank you.

[Pulse_GTO]

I would multiply the MAF table by 1.35 and see how your trims react. Fine tune from there.

[Fast4.7]

Need to measure the ID of both, calculate the area of both, then calculate the percentage difference. Assuming 0.040" wall tubing. 3.7-0.080=3.62 / 2 = 1.81. 1.81 squared x 3.14 = 10.29. 4-0.080 = 3.920 / 2 = 1.96. 1.96 squared x 3.14 = 12.06. Then calculate the difference in percentage. (12.06-10.29)/10.29 is 0.172 or 17.2%. Multiply the MAF table by 1.172.