This seems to be a common complaint on this car. Though I did not find anything with my visual inspection of the IAC valve, a new IAC valve or solenoid did fix this issue.

Engine Performance Diagnostics chapter 20


  • intermittent high idle
  • intermittent stalling
  • humming, moaning, hooting sound from the air cleaner box
  • idle speed control error fault codes

fix 50

  • replace idle air control valve (solenoid)

test shown

  • how to interpret IAC duty cycle on a scan tool
  • how to determine if the computer is causing or compensating for the idle speed problems
  • how to remove the IAC valve

Tools used

  • scan tool

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(Chapter 20) Idle Speed Problems and Testing

Related videos:

Ford Idle Air Control (IAC) valve test (how to adjust minimum idle speed):


P0506 IAC System RPM below expected (vacuum leak) - Ford:


Ford idle air control valve (IAC) test - stalling problems


How to test an idle air control valve (IAC) using a Picoscope - Ford:


end faq

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For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available as an eBook or paper book.

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