I HAVE A ROUGH IDLE IT FLUCTUATES BETWEEN 600 ...

  • Tiny
  • Anonymous
  • 2001 Ford F-150
  • 220,240 miles

I have a rough idle, it fluctuates between 600 and 1000 rpm. It only does this when the outside temperature is below 70 degrees. I have replaced the dpfe sensor, cleaned the mass air flow sensor, replaced o then sensors and still have this problem. It codes a P0174.

Thursday, November 15th, 2012 AT 4:05 PM

7 Answers

  • Tiny
  • racefan966
  • Expert
  • 5,127 posts

Did you check or replace the coolant temp sensor? If not and you have a digital volt ohm meter we can check it to see if it is bad.

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Thursday, November 15th, 2012 AT 4:56 PM
  • Tiny
  • nhemphill
  • Member

No I did not check the coolant temp sensor and yes I do have a digital volt meter.

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Monday, November 19th, 2012 AT 5:25 PM
  • Tiny
  • racefan966
  • Expert
  • 5,127 posts

Ok if you would when the engine is cold unplug and ohm the coolant sensor then also ohm the air charge temp sensor. Get back to me with the readings and the air temp too.

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Tuesday, November 20th, 2012 AT 4:31 PM
  • Tiny
  • nhemphill
  • Member

Not to sound in educated, but where would the coolant temp sensor and air temp sensor be located? I have a pretty good idea but want to be sure. The coolant temp sensor is right beside where the upper radiator hose goes into the watt pump and air temp is located after the mass air flow in the intake system?

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Tuesday, November 20th, 2012 AT 4:47 PM
  • Tiny
  • racefan966
  • Expert
  • 5,127 posts

Which engine do you have?

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Tuesday, November 20th, 2012 AT 5:04 PM
  • Tiny
  • nhemphill
  • Member

5.4 L

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Tuesday, November 20th, 2012 AT 11:19 PM
  • Tiny
  • racefan966
  • Expert
  • 5,127 posts

Here is a pic of sensor locations.

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Wednesday, November 21st, 2012 AT 4:42 PM

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