IAC - Idle Air Control - An electric valve or stepper motor that's threaded, one turn of the valve is called a "step". It's controlled by output signals from the ECM to open and close as needed to allow enough air into the engine for starting and idle operation. It's function is to bypass the throttle blade in the intake and allow enough air to bypass the throttle blade to run the engine.(Throttle closed) The more steps, the greater the amount of air enters the engine through the IAC passages. It's that black unit you can see just inside and over the top of the air cleaner.
From time to time they get gummed up from the oil mist that enters from the engine breathers and need to be cleaned out. If you look inside the throttle body there's a hole in the upper portion and that is what needs to be cleaned out. You'll usually see some black gunk come out when you clean it. The problem it gives you when it needs cleaning is an erratic idle speed and stalling and usually does not set a code unless they fail.
A can of carb cleaner will do the trick here. One thing is to blow the carb cleaner out with some low pressure air or the other sensors in the intake will set codes from the carb cleaner.
If you don't have any low pressure air to blow it out, just let it air dry for a while before turning on the ignition.
More on the IAC...
Harley Davidson Community
From time to time they get gummed up from the oil mist that enters from the engine breathers and need to be cleaned out. If you look inside the throttle body there's a hole in the upper portion and that is what needs to be cleaned out. You'll usually see some black gunk come out when you clean it. The problem it gives you when it needs cleaning is an erratic idle speed and stalling and usually does not set a code unless they fail.
A can of carb cleaner will do the trick here. One thing is to blow the carb cleaner out with some low pressure air or the other sensors in the intake will set codes from the carb cleaner.
If you don't have any low pressure air to blow it out, just let it air dry for a while before turning on the ignition.
More on the IAC...
Harley Davidson Community
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