I’m tuning my LT-8 for emission testing but I can’t seem to get the idle AFR leaner than 13.5. I have not touched the factory timing settings yet but I was wondering if I could run more advanced at idle and then lean out the AFR closer to 14.7? I’ve only done a rough tune in the NORMAL mode and now I plan to switch over to MATRIX mode.

Also I’m leaning out just before 3000rpm’s. I think I need to up my %stage from 50% to 65%.....will that help or should I just tune that out in the MATRIX mode?

Engine specs:
Stock S5 engine (stock ports)
Stock turbo & intercooler
Stock 550 primary injectors
720 secondary injectors
Idle fuel pressure 38psi

-Bill

 

Run an airpump into your exhaust. Run the gas tank low and put a couple bottles of rubbing alcohol in there. And a cat.. or 2. It was TOUGH getting mine to pass. Oh and make sure your out giving it one hell of a good run before you get there to have the turbo cook'n.

 

rotaries do not like to idle under 12.6AFR, you are misunderstanding stochiometric values, those are based mainly on piston engines and for cruising light load applications.

with a good catalytic converter and airpump blowing on it then toss AFR values out the window, lean it out til it just starts to want to hunt/misfire/die at idle then richen it up a tad and that should be good for emissions testing basis.