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IAC Testing - Rough Idle Question

Discussion in '4 Cylinder' started by cyclechopstop, Jan 19, 2011.

  1. Jan 19, 2011 at 6:25 PM
    #1
    cyclechopstop

    cyclechopstop [OP] New Member

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    So I have a rough idle once the engine warms up to operating temperature. I've done a full tune up and cleaned the throttle body and MAF. I've finally decided to clean and test the IAC and I still can't figure out if it is bad or not. I tested it using this method:
    http://www.ncttora.com/fsm/2003/Repair_Manual/03tacoma/sf5vzfe/iacvwoet/insp.pdf

    I didn't see anything happening and the motor only made a noise when I connected it the first way. Does this mean the motor is bad since it didn't do anything when connected the second way? Any help would be greatly appreciated. I really want to get to the bottom of this.
     
  2. Jan 19, 2011 at 7:50 PM
    #2
    brelandt

    brelandt Well-Known Member

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    Terry
    Dublin, CA
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    04 Prerunner reg cab SR5
    3" lift front and back
    was the valve open when you performed the second test? it might be good. plugged with carbon? Would cause the motor to stick. Try cleaning it up perfectly. If it still does not do what the instruction says it suppose to do then time to replace it. Also air in the coolant can cause the IAC not to work right.
     
  3. Jan 20, 2011 at 3:14 PM
    #3
    cyclechopstop

    cyclechopstop [OP] New Member

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    I don't really understand what I was looking for. Basically I cleaned it up and the first test would make a noise, but I didn't see anything happening and the second test didn't do anything at all... not even a noise. I could see through from one port to the other so I'm assuming it was open, but not sure. Thanks for the input. What should it do when I connect it the second way?
     
  4. Jan 21, 2011 at 11:17 AM
    #4
    brelandt

    brelandt Well-Known Member

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    Terry
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    Vehicle:
    04 Prerunner reg cab SR5
    3" lift front and back
    re-read those instructions on testing the motor carefully again. neg stays the same and when you place positive to one pin it closes (RSC). then place the positive lead on the other pin (RSO) and it should open. The pictures shows you the terminals orientation.
    Very easy test to do. If it does nothing on any of the steps then it's either physically stuck or the motor is shot. If it stays open the truck will run lean and that is NOT good.
     
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