RomRaider

Looking to put together a nice "stage 1" file for my 2017 STI (AE5Z000V).

My only problem is the Cobb SF intake, does anyone have a good starting point in terms of MAF scaling?

On the stock tune with the intake (yes I know bad and shouldn't be done, was removed right after) I got an extended crank and strange cold start behavior.

Physical measured area difference is about 30% but that seems like such a large bump to make in the scaling.

Any help is greatly appreciated!

so what i normally do on an intake I've not tuned before is to let the car go through a cold start and warm up. Once its up to temp then take a look at your A/F learning and A/F correction values, you'll see they will probably be at like +10 or something so take that value and bump the whole maf scale by it as a very rough starting point. From memory the cobb kit does need quite a bit added in before you get back to target AFR.

After tuning many cars with these intakes there is no consistent scalar to use, you really wanna have a wideband to scale maf in OL.

You can get it sort of in the ball park range if you follow your fuel trims during CL under mid load and globally multiply the maf scalar globally but it most likely wont be linear to get it dead on using say 15% or whatever the fuel trim error may be.

Scaling it globally base on idle / low load fuel trim is really just "ball parking" it, it can still be off by as much as 10-20% at high loads which is a huge deal. I've seen intakes that require negative scaling at idle but positive scaling at high air flows.

A wideband is a must for proper fuelling.

yes just to clarify my suggestion was only to get you somewhere in the ballpark so you can start properly tuning it in with your wideband. If you dont have a wideband yet then pop the standard airbox back on until you're ready to tune.