IAC motor question HELP
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IAC motor question HELP
I have had to replace the IAC (idle air control) motor on my truck three times in less than a year. At 47.00 apiece it is getting old fast. Any ideas as to what could be causing these things to go bad or get so dirty they start whining? 1999 4.6. Thanks!!
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First thing is to be correct, it is not a motor in any way.
Next, you need to explain why you think you had to replace it and what was the drivability issue you had. They normally don't go faulty that often, even over the total life of a truck.
I am not trying to be smart but it's important get the facts as you know them for any help to be worthwhile.
.
IAC background operation:
It is a spring loaded 'dash-pot' that is pulsed by an electrical signal from the computer to it's solenoid coil..
The pulsing opens a pintel to allow air to bypass the throttle plate.
The rate is tries to close is the spring loaded slow return action (dash pot).
The crank sensor tells the computer what the engine rpm is and corrects it to within +/- 50 rpm by pulsing the IAC opening amount addiing/subtracting air until the rpm agrees with a software table by a reference compair.
Next, you need to explain why you think you had to replace it and what was the drivability issue you had. They normally don't go faulty that often, even over the total life of a truck.
I am not trying to be smart but it's important get the facts as you know them for any help to be worthwhile.
.
IAC background operation:
It is a spring loaded 'dash-pot' that is pulsed by an electrical signal from the computer to it's solenoid coil..
The pulsing opens a pintel to allow air to bypass the throttle plate.
The rate is tries to close is the spring loaded slow return action (dash pot).
The crank sensor tells the computer what the engine rpm is and corrects it to within +/- 50 rpm by pulsing the IAC opening amount addiing/subtracting air until the rpm agrees with a software table by a reference compair.
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The thing starts "whining" kinda like a tug boat. If you barely touch the gas pedal it stops whing ie IDLE control. I put a new one one it when a 40 year ford mechanic told me that was the problem. It stopped. 2 months later it started again. I figured since the one i bought was a 19 dollar ebay one I had gotten ripped off. I went to Ford and got the one thats one it now and it has been about 3 months and now it is whining. As long as you are touching the gas pedal it is fine. The second you stop it starts whing.
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Mine's been doing the same thing, and it has nothing to do with cost. The one being used now is a Motorcraft, and was $85.00. It's also the first one to humm or whine at idle speed. I don't care for that, but it does everything else it's suppose to do.
Incidentally, this is IAC #5 in the last 4 1/2 years. No explanation for that. It's a 1999 4.6, and used the original for 7 1/2 to 8 years. The only thing I can think of is some sort of periodic electrical fault. In every case, they flunked the pin test for signal, resistance.
Since the truck I want/need is $58,000, I guess I'll keep this one running like new ( humm included).
Dave
Incidentally, this is IAC #5 in the last 4 1/2 years. No explanation for that. It's a 1999 4.6, and used the original for 7 1/2 to 8 years. The only thing I can think of is some sort of periodic electrical fault. In every case, they flunked the pin test for signal, resistance.
Since the truck I want/need is $58,000, I guess I'll keep this one running like new ( humm included).
Dave
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