The crankshaft position sensor doesn't affect idle speed. When it starts to fail, it does it when it gets warm, then will work again after cooling down about a half hour. It CAN cause intermittent problems if you didn't use a spacer to set the critical air gap when you installed it.
Idle speed problems have two common causes. The most common one is the battery was recently disconnected or run dead. The Engine Computer has to relearn "minimum throttle" before it will know when to be in control of idle speed. Until that happens, the engine will idle so low it may stall unless you hold your foot on the gas pedal, and you usually won't get the nice idle flare-up to 1500 rpm when you start the engine.
The less common cause is an air passage around the throttle blade that is plugged with carbon. Controlling air flow through that passage is how the computer controls idle speed. If it's plugged, idle speed won't increase when the computer wants it to.
SPONSORED LINKS
Sunday, July 17th, 2011 AT 9:12 PM
