Subaru Open Source MAF Scaling - Predefined Curves

In the practical reflash course there is a big emphasis placed on calibrating the mass airflow sensor, especially If you have a modified intake. Generally, my understanding of the method recommended to calibrate it is as follows:

1.) Start out with a broad %age based adjustment to the curve based on the difference in the cross sectional area of the MAF housing (eg: +20%)

2.) Collect AFR data in various load states (eg: MAF voltages) and RPM levels, for both open loop and closed loop states.

3.) Compare measured AFR data to commanded AFR data to obtain trim levels / error

4.) Adjust MAF curve based on error at various points in the observed error data

Rinse and repeat until error is at a minimum.

Completing this process without a dyno via road tuning obviously would take considerable time to generate the required data in all the various states, so Im wondering.... If you have an intake that likely already has had an accurate MAF curve generated for it (eg: Cobb SF intake)... would it not make more sense to just seek out some kind of MAF curve file/data for that specific MAF housing rather than attempting to do the data collection/adjustments yourself?

Obviously this wont work for every intake but In my case finding a MAF curve seems like a better option and I would imagine a lot more work has been put into getting a good MAF curve for that intake than I would be able to do myself via road calibration.

You could try and find a pre-defined curve, however, you'd still need to validate this to be sure you're not entering junk.

Normally, what happens is once you've tuned a few cars you build up a database of your own that you can refer to and know should be good.

G,

While this may seem like a lengthy process at first, with enough practice it can be done in a couple minutes. At first take your time, enjoy the process, keep your curve smooth by avoiding step changes, and avoid using data collected during transients.

While prior work performed on an intake can save time on future projects as Chris mentioned, ideal MAF scaling won't be the same on every vehicle using that MAF housing. In practice, MAF based tunes without VE correction rely on the MAF scaling table to account for more than MAF scaling.

In your #2 I'll just clarify in closed loop as long as the car is staying on target, you can use the total trim (short + long term) to know what % correction to apply to the MAF scaling.

Then in open loop, the actual AFR error to target AFR relationship shows you the correction needed to the MAF curve.