How does idling work?

[Maelfyn]

Is this electronically controlled by the ECU or something? Makes the car idle within a certain range? If your car fails to idle, what could be wrong? If the throttle is closed I don't understand where the air is coming from allowing it to idle.

[autxr]

The throttle body has an air bypass built into it. So, with the throttle plate closed enough air goes by to feed the engine at idle.

If the car is running poorly at idle there are a lot of things that could be wrong. Faulty sensor(s), plugged air bypass, a vacuum leak (too much air will cause a stall too), clogged/dirty injectors, etc.

Scott

[Slant]

Why is it that you idle higher when running A/C?

[tool462]

It adds load to the engine. It would probably stall if the idle was set lower.