RomRaider

Tried rescaling the front O2 sensor scaling today. It seems to work at idle where I see a measured AFR of ~15.8. Once moving though, the ECU adds fuel until I see about 14.8. Probably adding enough fuel to "toggle" the rear O2 sensor between rich and lean.

I will try the LC-1 analog output when I have some time tap the ECU harness for the rear O2 signal.

I just recently picked up a copy of the new RACE Tuner software for the APv2 and they have a "Closed Loop Target AFR" table for the AT/MT at both IDLE and a very wide load/rpm range. This table let me go over 14.70, I am currently testing 15.0:1 with good results.

With the 32-bit ECU, the CL target is always 1.0 lambda (which you cannot change). However, there are a number of correction factors that could be used to impact fueling - this is probably what Cobb has done. With the 16-bit ECU you can manipulate the actual CL target and various correction factors are applied to the target.

To make my '06 WRX run leaner than Lambda=1 in CL, I had to:

- Rescale Front O2 sensor scaling
- Rescale MAF below 2.8V to keep fuel trims ~0%
- Replace the Rear O2 sensor signal at the ECU with the Analog output of the LC-1 (programmed to toggle high/low near 15.6AFR)



Will see how well it runs like this for the next while.

Airboy, just wondering how it ran this past week. Got my LC-1 at home waiting and was looking to do the same.

Hopefully you can duplicate or find that table the is in the Cobb software, it helped my car considerably with freeway cruise. At idle I could see the AFR#1 showing 15.06 or higher depending on what I set it to in the 3D table.

The 2008 model also has this so it may be helpful for any of the years that contain it. The 2008 model is 11x11 with 800 to 5600 rpm and 0.20 to 1.60g load. The 2006 model is 11x10 with 800 to 5000 rpm and 0.20 to 1.60g load.

Messing more with closed loop fueling is on my to do list in the future. Just one of those things that I haven't spent too much time with for the 32-bit ECU but plan to.

It ran fine over the last week. Had some extend highway driving as well. I am going to add a bit of timing to the area below 1g/rev to compensate for the slower burning mixture.

Thanks for the comeback. Last tankfull I changed the AFR Sensor scaling, MAF scaling and used a voltage adder on the rear O2 sensor but it still didn't trip the sensor to rich all too often during the commute. AFR's went from an average of 14.53 the prior week to 15.13 this week. Not a drastic change but I did get 20 more miles on this tank. EGT's actually went down 50 degrees but then again weather was cooler. Knock seemed no worse than stock either. Want to try and push it a bit more now with the LC-1.

Cheers

Bump for any updates. I plan to play with this when I get my STI next month. The LC-1 will be permanently installed.