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Engine slightly revving while in idle


newnthused

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I've cleaned the IAC valve and throttle body. I also change the spark plugs and wires.

My truck starts at a pretty high rpm. Hits about 1500 then after 3 seconds jumps to 17. Warms up to about 1400 then down to 800 after driving around a bit.

But especially when it hits this lower range, like when I come to a stop, the engine revs just a tad like it's huffing and puffing. You can see the tach jostle just a bit. I'm wondering if this crack in the line going to the for has anything to do with it or if this is a problem.
Or if anyone else would know where to point me that would be great. Thanks
 

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franklin2

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That cracked line is the fuel line. I am assuming that is just the protective cover, since if it was the actual fuel line you would have a fuel leak.
 

RonD

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That is the fuel line IN, from pump and filter, if its not leaking gas then not a problem
The line above it is the Return fuel line, it attached to the Fuel Pressure Regulator, just FYI

How old is the PCV Valve?
This is a "metered" vacuum leak
It should be changed every 3 oil changes, and cleaned on each oil change

After engine is warmed up and idling unplug the IAC Valve's 2 wire connector
RPMs should drop to 500-600 engine may even stall, either is good, it means no vacuum leaks
If if idle stays higher then either throttle can't close all the way or there is a vacuum leak somewhere

Also you should set/check the spark timing just to be sure its OK
 

newnthused

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Ford Ranger XLT
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That is the fuel line IN, from pump and filter, if its not leaking gas then not a problem
The line above it is the Return fuel line, it attached to the Fuel Pressure Regulator, just FYI

How old is the PCV Valve?
This is a "metered" vacuum leak
It should be changed every 3 oil changes, and cleaned on each oil change

After engine is warmed up and idling unplug the IAC Valve's 2 wire connector
RPMs should drop to 500-600 engine may even stall, either is good, it means no vacuum leaks
If if idle stays higher then either throttle can't close all the way or there is a vacuum leak somewhere

Also you should set/check the spark timing just to be sure its OK
The PCV valve is probably old as heck. I got passed a star certified smog check recently and the PCV valve came back with good readings, but there is some mean black stuff around it. Could probably use a good clean.

I'm still having the high idle issue. I'm going to try your IAC valve trick to see if it drops. I also want to check for vacuum leaks but am nervous to try the carb cleaner method because of flammability.
 

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