Idle Air Control Valve - IAC?

Tiny
SSCATHERINE
  • MEMBER
  • 2001 FORD RANGER
Okay, I need help. I just had a mechanic put a new/used motor in my truck. It runs smooth and quiet, but there is a problem, it won't stay running. We put a new mass air flow sensor on it and a couple other new parts that I don't think have anything to do with the problem. If you unplug the wires that go into the idle air control valve the truck will start up and idle. If you plug it in, the truck shuts off. Also, the oil pressure gage when you are starting the truck jumps erratically from 0 to mid way instead of just moving up, it jumps. My mechanic and I are both almost done, can not figure this out. Can you show me how to replace the IAC PLEASE HELP!
Sunday, November 22nd, 2009 AT 8:25 AM

36 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
It does sounds like the IAC is not working correctly here is a guide to help walk you through the steps to replace it with diagrams below to show you how on your car.

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

and

https://www.2carpros.com/articles/stall-at-idle

Check out the diagrams (Below). Please let us know what happens.
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Sunday, November 22nd, 2009 AT 8:31 AM
Tiny
SSCATHERINE
  • MEMBER
  • 2 POSTS
That fixed it! Thanks for the guides they helps help this site is great.
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Sunday, November 22nd, 2009 AT 8:36 AM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Good to hear, please use 2CarPros anytime we are here to help.
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Sunday, November 22nd, 2009 AT 9:05 AM
Tiny
JOHN HARPER
  • MEMBER
  • 2 POSTS
  • 2000 FORD RANGER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 110,000 MILES
My truck has recently been idling abnormally high when cold started. I unplugged the IAC and it drops the idle then plug back in and it usually stays lower. I cleaned the passages in the IAC, but the problem still occurs a few times a week. Does my IAC need to be replaced? Is the computer doing this? Hope not.

John
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Friday, October 9th, 2020 AT 9:48 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,071 POSTS
Has the check engine light ever come on?
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Friday, October 9th, 2020 AT 9:48 AM (Merged)
Tiny
JOHN HARPER
  • MEMBER
  • 2 POSTS
The check engine light has not gone on while this problem started, pretty sure it's the IAC valve.

John
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Friday, October 9th, 2020 AT 9:48 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,071 POSTS
Chances are you are right, but I hate to recommend things if I am not sure. Without the check engine light, it is a guess. That is the part I hate.
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Friday, October 9th, 2020 AT 9:48 AM (Merged)
Tiny
2000RANGERGUY
  • MEMBER
  • 1 POST
  • 2000 FORD RANGER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 132,000 MILES
When replacing the IAC are there any reset procedures or manual calibrations that must be done on this vehicle?
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Friday, October 9th, 2020 AT 9:48 AM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
No adjusting should be done make sure the air way clean before installing the new one after installing turn key on for about a min then off for a min start and let it idle
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Friday, October 9th, 2020 AT 9:48 AM (Merged)
Tiny
NOFISH
  • MEMBER
  • 1 POST
  • 2000 FORD RANGER
  • 4 CYL
  • 2WD
  • MANUAL
  • 245,000 MILES
Do I need to do anything other than replace the IAC valve like re do something to the computer? In my 2000 ford ranger 2.5L
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Friday, October 9th, 2020 AT 9:48 AM (Merged)
Tiny
ERNEST CLARK
  • MECHANIC
  • 1,730 POSTS
No, you don't have to do anything. If there's a code in the computer (check engine light), then you'll need to turn it off with a scan tool. But the computer has an internal memory and will recognize the new part without you doing anything.

If you disconnected the battery, the computer will reset itself. It may seem like it's driving messed up for a while, but that is only the computer in "re learn" mode. It'll clear up.
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Friday, October 9th, 2020 AT 9:48 AM (Merged)
Tiny
DAVID NAUCH
  • MEMBER
  • 2 POSTS
  • 1999 FORD RANGER
  • 4 CYL
  • 2WD
  • MANUAL
  • 75,000 MILES
I have a 1999 Ford Ranger 2.5L I4 5 speed manual transmission. Occasionally, the engine will not return to idle speed between shifts. The idle will keep the engine @ rpms estimated above 2 - 3K. I have replace the Idle Air Control valve (IAC) but the problem still exists. It only seems to be a problem after the vehicle has been driven and sits for some time. If I start from a cold engine I don't notice the problem but after sitting for 30 minutes to an hour or so is when the problem seems to develop.

Could it be temperature related?

Thanks,

Dave
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Friday, October 9th, 2020 AT 9:49 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,071 POSTS
Has the check engine light come on?
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Friday, October 9th, 2020 AT 9:49 AM (Merged)
Tiny
DAVID NAUCH
  • MEMBER
  • 2 POSTS
No, the check engine light has not come on!

Sorry, I should have noted that in my question.

Dave
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Friday, October 9th, 2020 AT 9:49 AM (Merged)
Tiny
KIKILYNN
  • MEMBER
  • 1 POST
  • 1999 FORD RANGER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
My idle is too high and I would like to know how to adjust the idle on a 1999 ford ranger 6 cyl. Thanks
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Friday, October 9th, 2020 AT 9:49 AM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
The computer adjusts the idle on your truck automatically. If it is too high, you most likely have a vacuum leak. Pop the hood and see if you can hear a loud hissing noise, if so locate it and repair the hose as required. Fords have issues with the lines from the PCV valve to the intake leaking. Also try spraying the intake carefully with carb cleaner while it is idling, if the idle changes, you have sprayed a leak. If there are no vacuum leaks, the Idle Air Control Valve may be bad, but check forvacuum leaks real good first. If the check engine light is on, have the PCM scanned for any trouble codes, this may point us in the right direction for a fix
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Friday, October 9th, 2020 AT 9:49 AM (Merged)
Tiny
SKAIMDUANE
  • MEMBER
  • 1 POST
  • 1998 FORD RANGER
  • 260,000 MILES
My truck has been idling very rough this year, recently my "98 ranger has been stalling at most every stop light or sign. It is a manual 5 speed 2.5L engine. I have been working on this on and off for the last 6 months. I changed all of the spark plugs & spark plug wires. What advice can you give me to remedy this? Thank you for taking the time to help.
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Friday, October 9th, 2020 AT 9:49 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,071 POSTS
The iac needs removed. Have a helper turn the key from off to on. There is a pintel valve that should move on the iac. Also, check for vacuum leaks.
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Friday, October 9th, 2020 AT 9:49 AM (Merged)
Tiny
DAVID KITE
  • MEMBER
  • 2 POSTS
  • 1998 FORD RANGER
  • 4 CYL
  • 2WD
  • MANUAL
  • 89,000 MILES
I have 1998 Ranger 2Wd, 2.5 liter engine. When I push the clutch in to coast to a stop the engine continues to race at high RPM. If I let out the clutch the engine is dragged down to appropriate speed, but if I push the clutch back in the RPMs race back up to high speed until I come almost to a complete stop. Then the RPMs drop to idle speed.
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Friday, October 9th, 2020 AT 9:49 AM (Merged)
Tiny
DANLESABRE
  • MEMBER
  • 230 POSTS
This sounds like the IAC needs to be replaced here is the location in the diagrams below. Check out the diagrams (Below). Please let us know what happens. HEre is the IAC location in all three engines that come in your truck.
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Friday, October 9th, 2020 AT 9:49 AM (Merged)

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