Quote:
Originally Posted by redpoint5
I don't know anything, but I'd think main concerns with low idle have to do with alternator power output, AC cooling ability, and NVH concerns.
On my motorcycle, I lower the RPM to the point that I end up stalling it too frequently, then bump it up slightly.
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I think you are right and none of those are much of a concern in my application.
Alternator works great. Even with my lower idle and all electrical loads on, the voltage always stays above 14V since the Acura TSX alternator is so overkill for the small electrical demands of my Civic, especially since it has all LED lighting.
I don't have AC, so that's not a concern to me. But as weak as some AC systems are at idle, I could definitely see an even lower idle being a problem on some vehicles.
NVH is somewhat of a concern to me, but not much. It's plenty smooth at around 650 RPM and realistically a 4 cylinder on stiff mounts is never going to be as smooth as something like a straight 6 or V8, which is fine with me.
Actually at least the first of those two problems could easily be solved by simply programming the ECU to increase idle speed when the electrical load is high and/or voltage drops too low or the AC is on. As for why they don't do this, my best guess is probably because a changing idle speed could be annoying and might make people think something is poorly designed or malfunctioning.