I went from a 3 1/2" MAF to a 4" what changes
need to be made to the PCM ? any body have
the specs to put in ? a pic of the HPT file would be nice.
it is a 2011 6.2

 

I'm assuming you are referencing the size of the tube the MAF is in? If so you need to correct ve if you have not already and then make your MAF adjustments. I believe the sticky about tuning 101 address this if you have further questions.

 

Right, both airflow tables need to be re-tuned. It's now going to read a totally differnet amount of air coming into the motor because the intake tube is now much larger than before.

 

Not sure if this helps but this is a table for the lingenfelter 100mm maf

 

Oh Lord, please do not copy and paste some BS into your tune. Retune the truck the right way.

 

Amen. Please do not do that. Air flow modeling is how fueling is calculated. This is by no means a one size fits all equation. This is not a bash at all. This is all an attempt to help. Please read the stickies above. There is some real good info in there. This may help fill in some gaps for you as it has helped fill in some for me as well. I'll help if I can but Research is King in all of this. I sure wish I had all the answers but unfortunately The educational process is never over no matter who you are.