Starter problems
Sick 'n Tired
Joined: May 2006
Posts: 2,969
Likes: 47
From: League City, TX
I had the same problem on my mustang. The simple fix was to put the car in "On" for a few seconds before turning it over to "Start". That always worked. I don't recall if replacing the IAC (also known as the Idle Speed/Throttle Actuator) mitigated the problem.
IDLE AIR CONTROL (IAC) VALVE
NOTE: The IAC valve assembly is not adjustable and cannot be cleaned, also some IAC valves are normally open and others are normally closed. Some IAC valves require engine vacuum to operate.
The IAC valve assembly controls the engine idle speed and provides a dashpot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The PCM determines the desired idle speed or bypass air and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine RPM and increases or decreases the IAC duty cycle in order to achieve the desired RPM.
The PCM uses the IAC valve assembly to control:
IDLE AIR CONTROL (IAC) VALVE
NOTE: The IAC valve assembly is not adjustable and cannot be cleaned, also some IAC valves are normally open and others are normally closed. Some IAC valves require engine vacuum to operate.
The IAC valve assembly controls the engine idle speed and provides a dashpot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The PCM determines the desired idle speed or bypass air and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine RPM and increases or decreases the IAC duty cycle in order to achieve the desired RPM.
The PCM uses the IAC valve assembly to control:
- no touch start
- cold engine fast idle for rapid warm-up
- idle (corrects for engine load)
- stumble or stalling on deceleration (provides a dashpot function)
- over-temperature idle boost
Freshman User
Joined: Mar 2008
Posts: 45
Likes: 0
wow ok thanks a lot for the help. that information is very helpful to me.. im gonna try turning it on first though cause i dont want the dealership messin up my truck like they have before. ha ha thanks again!!!
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