Can anybody tell me _exactly_ how Chrysler PCMs determine 'fuel mixture lean' condition? I'm running Dodge Durango 99 on propane, and PCM consistently throws P0171 condition. Propane computer (Autronic) feeds emulated O2 sensor signal into vehicle PCM, and allows me to set emulation parameters: time low (0V) and time high (1V). I've tried reducing 'time low' to simulate richer mixture, but to no effect.
This has no effect on driveability btw... just would like to turn that damn Check Engine light off. It will always re-light after a couple of trips
Peter