High Idle Problem .. 95, 4.0L, OHV | Ford Explorer - Ford Ranger Forums - Serious Explorations
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High Idle Problem .. 95, 4.0L, OHV

dwbab

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City, State
Toronto, ONT
Year, Model & Trim Level
95 Eddie Bauer
My idle speed has crept up to 1,000 to 1,200 RPM
when warmed up. When I remove the connector from
the IAC valve it slows down to normal. I removed & cleaned the IAC valve ..... same symptom.
Could it be another sensor that is bad causing this ?
Appreciate any help !
Don
 



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Texan01

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Year, Model & Trim Level
1995 Explorer XLT
Check your coolant temp sensor (for the computer, not the gauge) cause on mine if the coolant temp starts climbing towards the red (bad water pump) the idle speed will start rising to around 1000-1500 rpm.
 






dwbab

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95 Eddie Bauer
Engine temp is OK...... not overheating ... temp guage showing normal. I checked the resistance of both the coolant and air intake temp sensors and both are OK. ?
 






B94Sport

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Is your idle RPM high in all gears or just drive? I was driving down the street and when I came to a stop my engine was idling at 1200 RPM... I shifted into park and it climbed to 2000 RPM! I figured it was something that the tranny repair shop had messed up, but after a quick inspection I discovered that the plastic sleeve around the end of the throttle cable by the TB had snapped in half, and caught on another piece further back, preventing the cable from ever going back in all the way and always keeping my TB slightly open... So I popped it back into place and all was well.
 






dwbab

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95 Eddie Bauer
In neutral it's at 1,000 to 1,200 RPM.
Still stays high when you put it in drive rather than the normal 650 or so.
I checked around the throttle & cruise cable ... the throttle closes OK .... cables are free.
 






Rhett

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Cape Girardeau, MO
Year, Model & Trim Level
94 Sport 4x4
Check for vacuum leaks all around--on the intake manifold octopus, on the intake tube, on the throttle body. And check all the vac lines for cracks and holes.
 
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dwbab

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I can't hear any vacuum leaks .... but I will check it out.
 






Opera House

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With IAC unplugged

The engine rpm should drop to the point that the engine almost stalls. If engine warmed up, it will run but too low to actually drive. So if the idle is decent there is something holding the throttle body valve open (I've seen them gunked and stick) or there is a vacuum leak.
 






Glacier991

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About a year ago I picked up a used vacuum leak detector... basically an untrasonic sniffer... for about $75. It came with a transmitter (great for finding wind sound leaks in a car, but the sniffer was GREAT at locating otherwise unfindable vacuum leaks.) Since I got it, I often wondered that shops never advertised their ability to find those pesky leaks using their equipment. Maybe if you check around to various shops and find one with such a device, they could easily help you localize any vacuum leak. Eyes and ears won't always do it.

Chris
 






Rydin Dirtay

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Could be something in the throttle body.. most vacuum lines being disconnected or leaky would cause a loss in RPM's i had a problem with sensor and had to replace them all.. usuall when one goes out most all of them follow suite for some reason. its always the part you dont check or replace thats royally f00ks you
 






dwbab

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95 Eddie Bauer
Question .... when I had the IAC valve disconnected
and removed I then cleaned it. While cleaning it I remember that the little valve disc inside it was not completely closed. It was open about 1/8 inch.
Should it have been closed while in my hand ... disconnected ?? Would a new one be open a bit like this ???
 






dwbab

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I changed the IAC valve. Still idling high at 1100 - 1200.
Drops to just under 1000 in drive.
 






Rhett

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Since you replaced the IAC, you probably eliminated the possibility of the IAC being the problem. So that leaves 2 things:
Is your throttle body/cable dirty?
And are there any vac leaks?
 






dwbab

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Rhett, Thanks for your help. I'm getting close to taking it to the dealer ! Throttle body looks good, butterfly not sticking and still resting on the stop screw. Throttle & cruise cable clean and not sticking. As for the vacuum leaks, all hoses look good & connected. Also, with motor running , a buddy of mine used propane all around the top end figuing that a leak would suck it in and the rpms would change but couldn't find any problem.
 






00sport4x4

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I Have an 2000 sport with a 4.0 ohv it idles at 1200 to 1300rpm cold in park and 1000rpm hot in park. I thought that was a little high but I took it to the dealer and they said that it was right where it should be between 800 to 1200 rpms hot.I was thinking about adjusting the idle myself?
 












dwbab

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rydinhigh,
If you mean a reset of the PCM module ..... I have had the battery disconnected a few times. Also tried another
PCM module a few days ago and the idle is still high
1100 - 1200 in park, 1000 in drive. After a reset and with the other module it seems to take about 2 - 3 min to sort itself out and then the idle goes right back up again.
 






springtensi0n

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95 XLT
i've never had a low idle [500] like everyone else seems to have. mine's always been around 1000. i tried adjusting my throttle body, but that didnt seem to do too much. when i started with my iac unplugged, i had to rev it up, then slowly ease it down. when it was a little above 500 rpm, it wanted to die so i had to give it more gas... if everyone else idles at 500, why does mine struggle to stay alive?
 






dogfriend

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'97 Sport 4x4
Originally posted by springtensi0n
i've never had a low idle [500] like everyone else seems to have. mine's always been around 1000. i tried adjusting my throttle body, but that didnt seem to do too much. when i started with my iac unplugged, i had to rev it up, then slowly ease it down. when it was a little above 500 rpm, it wanted to die so i had to give it more gas... if everyone else idles at 500, why does mine struggle to stay alive?

500 is too low, the 97 manual says hot idle should be 750 -830 rpm for both the 4.0 OHV and SOHC.

IAC and idle speed thread
 



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dogfriend

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Originally posted by Rhett Browning

And are there any vac leaks?

I agree with Rhett - I think you have an intake air leak or a vacuum leak that is letting too much air bypass the throttle body.

Off the top of my head, here are some possibilities:

Throttle body gasket
IAC valve or gasket
EGR not closing completely
Vacuum motor leak or other vacuum sys leak (brake booster, heater door controls,etc)

To see if it could be a vac motor leak, disconnect non essential vacuum hoses and plug the lines at the manifold - test to see if idle speed goes down
 






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