First off: Awesome thread.
I purchased a modified 2002 WRX from a friend a bit ago. Modified meaning non-stock looking maf, FPGreen, WRX Modded injectors short ram and intake hardpipe to turbo. So... lots of mods to the air intake path.
This car has been road tuned once by a reputable tuner, but still has a couple driveability issues I want to fix, so i'm starting with MAF scaling.
Injector scaling set to 780cc in the tune, havent touched it yet. This morning I did some logging with the Romraider MAF Scaling tool. Its results are below, what concerns me is that I have one area with 40% error and several around 25% in several areas and I need some advice: 1) Should I attempt to smooth out the entire Open/Closed loop curve based on results below. Its obviously way off, I put a proposed curve in there with the changes I would make, but it scares me to do 30% change at 1.72 G/Rev
2) Ultimately I want this car to be really dialed in, I want to have a good baseline without having to use the MAF scaling to band-aid everything. Given that its already modded heavily, what would be a good approach to be assured injector scaling and MAF Scaling are both accurate within a couple percent?
Below is a graph of a MAF Voltage vs MAF g/Sec. I used two different scales so you can see some detail down <100 g/Sec.
Measured = recommended curve from Romraider MAF Scaling Tool.
X-Tune = What the car came with
Modded = the changes i'm thinking about making
LGT/LGT Stock = Some stock MAF curves for sanity check
MAF Scale Closeup
, on Flickr
MAF Scale Full
, on Flickr