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Microtech idle AFR for emissions?

Old 08-22-06, 09:57 AM
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idle AFR for emissions?

Iím tuning my LT-8 for emission testing but I canít 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? Iíve only done a rough tune in the NORMAL mode and now I plan to switch over to MATRIX mode.

Also Iím leaning out just before 3000rpmís. 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

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Old 08-22-06, 04:01 PM
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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.
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Old 09-07-06, 04:59 PM
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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.
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