L31MaxExpress
I'm Awesome
Picking up on the idle issue. What does the IAC valve do ie open or close to say, increase idle speed (against a load) and are the injector durations altered? Curious as my LPG system is entirely independent of injector durations (not all LPG systems are) and my idle is as stable as can be asked for. When I've noticed the odd tremor idling it has been when running on gasoline but as not up to temp in that situation, I'm reluctant to condemn it as unstable.
The PCM first alters the timing, then if the error is too great for the timing control it moves the IAC. The 02 sensors provide feedback for the PCM to continuously vary the air/fuel ratio. The AFR swing from the factory is pretty aggressive, where I have it down to roughly a 0.02 lambda swing now rich and lean. 0.98 to 1.02 lambda.