Contour Enthusiasts Group Archives Forums Modifications 3.0L Duratec The 3L is up and running!

Todd, I can't answer that. From what I've seen there have been different MAFs on the same year and model of car, the calibration numbers being different.
This isn't a big deal as the computer can adapt to these different calibrations easily enough if you had to change it and if it was the only change.
As far as the 'size' of the MAF, regarding its airflow capability I would think all of the 2.5 MAFs would be pretty similar, in the 700 kg/hr range.

However, if the chip/tune has disabled the learning features, or if the maf calibration is off just enough combined with the added effects of different manifolds or hardware, displacement, TB size, etc., then I'd say it could knock it far enough out that you'd get driveability issues.

The biggest factors I've found in tuning this engine were:
the maf calibration and getting it correctly entered into the computer,
throttlebody size and amount of leakage past the throttleplate,
length of the intake tract between the MAF and the TB,
PCV system routing,
injector size.

Some of these are easy to fix, some not. The TB sizing issues can be hard to solve if you have a leaky throttlebody. I've even filled in the pre-drilled hole on most of the larger TB plates to reduce airflow at idle so the engine will be able to drop down to 700rpm range. I had one TB that was leaking around the shaft bearings enough that it would idle at 800-900rpm even with the IAC tube pinched completely shut.

The only way to determine the throttlebody leakage issues (assuming you have no manifold leaks) is to plug/pinch the IAC line and Plug off the PCV line so that they don't introduce any more air.
If the engine stalls out, then the PCM should be able to control the idle by adjusting the IAC. IF it will still idle with the IAC tube pinched off, then how high is the idle and try plugging the PCV line off. Eventually you can determine where the air is coming from and work on it. THe troublesome TB that I had gave me lots of grief until I installed sealing o-rings with grease onto the shafts on the outside of the bearings. THe it worked like a charm.