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-   -   RPM's stay high or vary randomly at idle (http://www.focusfanatics.com/forum/showthread.php?t=309495)

p58ff 02-17-2013 09:44 AM

RPM's stay high or vary randomly at idle
 
As the title says the engine speed has been acting strange recently. I first noticed that the engine speed was staying high when I stopped for stop lights and the like. It was up in the 2K RPM zone. The accelerator pedal is not sticking from what I see.
Yesterday after using the car to jump a dead battery on my truck the engine speed just started climbing then went back down. After a few minutes it did it again and I also noticed that both cooling fans came on and I thought I heard the A/C compressor 'clack' on. Again it cycled and after a minute or so it was normal again.
I'm looking for some ideas on places to have a look to solve this mystery.
Pav

whynotthinkwhynot 02-17-2013 10:15 AM

Is the DEF or DEF/FLR selected in the vent selector? If so, that will turn on the AC even if you have heat on.

p58ff 02-17-2013 12:42 PM

It could have been as it was in the 30* degree temp range and I was clearing snow among other things. I had forgotten about that possibility.
That may account for the fans spooling up but that still leaves the erratic idle speed/raised idle speed issue during regular driving.

whynotthinkwhynot 02-17-2013 01:32 PM

Not really, as long as you're on those settings the AC idle is going to be set.

Which engine do you have? Have you checked the usual suspect- the PCV valve line? That or any other vacuum leak you can find under the hood by listening for a hiss. Follow the VECI vacuum schematic for locations. Just trace down the lines- there are only about 5 or 6.

focusse13 02-18-2013 07:55 AM

IAC valve maybe?

p58ff 04-21-2013 10:06 AM

IAC did not help. Thinking it might be a vacuum leak as I just noticed the rubber fitting that connects the PCV line to the throttle body was in bad shape. Need to address that first I think.


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