Thanks Jack for your effort.
I understand your point of view and the method how to show that the oscillating idle is due to LPG setup. However, how can this explain that the idle only oscillates when the engine is cold after the engine had enough time to cool down (~8 hours when outside temperature is ~10C). In summer or when the engine is warm, the engine runs perfectly with both petrol and lpg, at idle or when driving, when the engine is "cold" or warm... It actually runs perfectly without absolutely any difference between petrol and LPG. If your reasoning would hold for my case, than I would have problems regardless of the temperature. Am I missing something here?
I anyway tried this morning what happens when the idle oscillates on LPG and I switch back to petrol. There is no rise or drop of RPM. The RPMs simply stop to oscillate. If I switch back to LPG, no drop or rise of RPM as well. It immediately starts to oscillate around the petrol RPMs. Sometimes the oscillations dampen but most of the time they remain until the engine is warmer. When the engine is warm and I switch from LPG to petrol or the other way, you can hardly see any change in RPM.
Also, when I started the engine this morning (after I drove on LPG yesterday an ECU didn't have time to recalculate fuel trims for petrol), the RPMs initially raised a little above 1000 and then fell to about 900 like you suggested that it would be in case when ECU had correct trims for petrol.
What I also tried once is that I reset the ECU first thing in the morning but the problem was still there...
I also noticed that sometimes the oscillations are stronger and sometimes (very very rarely) there are no oscillations at all or only a couple. However, I can not figure out any correlations...
Cheers,
Jan
|