1987 2.3 high idle


Fordstraydog

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Help, I got a 87 ranger with 2.3 . After driving for 10mins or so it idles at 1200 to1400 but if I have a 1/4 tank of gas or less it's fine. Any help would be appreciated thanks
 


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rusty ol ranger

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87 2.3 is EFI correct?

If so clean/replace your IAC. (Idle air control).
 

racsan

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Check all your vacuum lines/connections
 

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I appreciate the help!!! Checked vacuum lines ,nothing . When I drive it and it stays idling high, I unplug IAC and it goes to normal. So leads me to a sensor or something in wiring causing it. I unplugged the tps too when it's high and it stays high . Can intake air temp sensor cause this?
 

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How I found it runs fine under 1/4 tank of gas . Drove to feed store one morning it ran fine so I drove it around more and it was fine. Stop at the gas station filled it up drove home which is a mile from there.I ate lunch then drove it and high idle was back. I siphoned gas to 1/4 tank where it was before I filled it up and it was good again!
 

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How did you check for vacuum leaks?
 

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How did you check for vacuum leaks?
Unplug and plug with caps, spray carb cleaner which a couple people say do, and even took it to a shop and they checked too. I found the tank vent grommet was loose so I changed that too
 

rusty ol ranger

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Does it seem to run rich when warm?
 

rusty ol ranger

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Rusty ol ranger, I don't think so. It's like something is telling it to idle up,. Going to ohm out intake temp sensor tomorrow hopefully! !!
Check your coolant temp sensor while your at it.

Not the single wired one going to the gauge, the 2 wired actual plug one that tells the ECM how hot/cold the engine is.
 

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I just fail to see how fuel level in the tank has an effect on engine RPM... but strange things happen.

When you unplug the IAC you say it goes to normal.. what RPM is that? The RPM should drop low... maybe to low to run and stall.

Nine times out of ten... when you get this high idle condition... you are bypassing air around the throttle plate (Vacuum Leak). I know you've checked it but I can't help but think something is being missed... maybe a small leak in the brake booster... intake manifold.... throttle body base. I would check it again... and check it when the high idle condition is present.
 

Fordstraydog

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Check your coolant temp sensor while your at it.

Not the single wired one going to the gauge, the 2 wired actual plug one that tells the ECM how hot/cold the engine is.
The temp sensor that's below thottlebody was changed out recently . Had issue before and after.thanks for your input it helps
 

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I just fail to see how fuel level in the tank has an effect on engine RPM... but strange things happen.

When you unplug the IAC you say it goes to normal.. what RPM is that? The RPM should drop low... maybe to low to run and stall.

Nine times out of ten... when you get this high idle condition... you are bypassing air around the throttle plate (Vacuum Leak). I know you've checked it but I can't help but think something is being missed... maybe a small leak in the brake booster... intake manifold.... throttle body base. I would check it again... and check it when the high idle condition is present.
OK I'll go back and recheck that. When I say drops it goes from 1400 to 700or a little lower. Thanks keep helping I need it! !!!
 


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