Originally Posted by
RobZL1
Zeroing the home cell means to chose an ITT cell that is "normal" where your car typically runs. For example, the 122 deg.F cell in the ITT table.
Do your MAF tuning while the car is running at close to 122deg.F ITT. Once you have that squared away, and your MAF is looking good at 122 (or wherever yours is), then you leave the MAF curve alone and adjust for fueling error in the other ITT temperature cells by adding or removing a small amount in the relevant cells in the ITT table.
Otherwise, you'll chase your tail forever trying to get MAF perfect when the ITT changes. It makes a pretty significant difference to fuel trims when your ITT changes. A small offset can be a significant adder percentage-wise, especially at low pulsewidths with larger injectors.