[mbtoloczko]

Finally did some AFR runs. I don't have rpm, TPS, or MAF datalogging enabled yet. Here's the mods I've done to my car:

1) I'm running an Impreza 2.5 RS fuel pressure regulator in my car which should richen the AFR by one point in open-loop mode (greater than 25% throttle).
2) The car has a custom exhaust.
3) I'm running aftermarket sparkplugs.
4) I've got a very mild ram-air system installed.
Otherwise, the motor is stock.

My first general observation is that when the engine is operating in closed-loop mode (light throttle), the afr is right on stoich. I'm surprised the SVX doesn't get better gas mileage.

My second general observation is that at aggressive throttle positions where the engine is operating in open-loop mode, the afr is super rich with the Impreza 2.5RS fpr. Its in the range of 12.5:1 to 11.5:1. No wonder the exhaust tips on my car are covered in soot!

Anyhow, I did four runs, with each run a little different. Some of the plots are shown below. In every case, once the ecu goes open-loop, the afr quickly richens to 12.5:1, and then gets even richer as the engine goes past 5000 rpm.

So, the next step is the throw the OEM SVX fpr back on the car and do another set of runs. Glad I kept it. This should put the afr in the range of 13.5-12.5:1, but its probably not the best solution either. Below 5000 rpm, the afr will be a little to lean for max power, and then beyond 5000 rpm, it will be right on the money for max power. The best solution would probably be to install an SAFC-II so that the afr could tuned to 13:1 across the entire rpm range.

It would be very interesting to see what afr values would be obtained on a completely stock car.

Run #3 (afr vs time): 3rd gear, WOT, uphill



Run #3 (afr vs rpm): 3rd gear, WOT, uphill



Run #2 (afr vs time): 4th gear, WOT, slight incline



Run #4 (afr vs time): 3rd gear, about 1/2 throttle, slight incline