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Old 12-25-2008, 03:06 PM
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Default Why wont my 4.0L Ford Ranger stay running when cold?

I have a 1997 Ranger (2WD, 4 litre, 5 speed) and when it is cold it starts right away and goes into high-idle (approx. 1800 RPM) but unless I am giving it gas, the RPM's drop after 5 or 6 seconds and it either stalls out or idles very low (approx 200-300 RPM). Once it warms up for a minute or two it idles fine and continues to idle normally when started providing the engine is still warm. Also, I am not sure if it is related, but at time when I take my foor off of the accelerator while driving, the accelerator seems to stick for 3-4 seconds, and if i press the clutch while it is stuck the RPM will jump when go back to idle as normal. Any ideas?
I dont think that the idle hanging is a normal function. It only started when the other problem started (wont stay running on its own when cold) and when I take my foot off the gas, the vehicle continues to accelerate causing it to lunge forward fro 2-3 seconds, and if I push the clutch the idle spikes 800 or so RPM before dropping to idle speed.
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Old 05-18-2009, 08:33 AM
night455 night455 is offline
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Join Date: May 2009
Posts: 18

Clean your IAC valve... it bolts onto the intake and lets the truck idle... you can replace it for 100 bucks or so though...

Another thing check every inch of the intake, if there's any holes or loose fitting clamps replace and tighten... sometimes a simple air leak into the intake will cause the truck to idle higher...

A third option would be change the O2 sensors, because when the truck is cold it needs more fuel to start, and if there is a bad 02 sensor it might stay stuck on causing the engine to flood and bog down.

Back to the sticking accel pedal... Visually examine every inch of cable, make sure that there's no damage to it causing it not to return. Another thing on that is to look at the throttle body "flapper" spring, that might just be gunked up and not responding to pressure like it should...

These are a few items that come to mind just by reading your initial post... Hopefully something in it will be your trouble.

Last edited by night455; 05-18-2009 at 08:36 AM. Reason: forgot a detail
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Old 05-18-2009, 10:46 AM
98blownranger 98blownranger is offline
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Join Date: Feb 2009
Posts: 718

yes it is your IAC valve very easy fix they are about $30 to do yourself, it is not your O2 sensors but they could be bad but will not have anythign to do with your problem
Originally Posted by redrumedge View Post
98blown you should be an MD! that's the same stuff my doc asks and ur spot on man!!!
98 4.0 2wd-----supercharger fully build heads cam...all show with go......3 time world of wheels champ 5 time national winner

lots of ranger parts for sale leftovers from my 94/96
96 sitting on the frame, waiting to go lower

custom billet parts by me intake adapters and billet steps for the step sides

please sign my guestbook!!
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Old 07-28-2010, 06:52 PM
jarhizzy jarhizzy is offline
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Join Date: Jul 2010
Posts: 4
Default Re: Why wont my 4.0L Ford Ranger stay running when cold?

got the same problem. to me it sounds like the IAC. if you dont want to buy one, try cleaning it with some electrical cleaner. i cleaned mine and it was carbon black. After i cleaned it it worked better.
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Old 08-29-2010, 02:47 AM
smokebug smokebug is offline
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Join Date: Aug 2010
Posts: 4
Default Re: Why wont my 4.0L Ford Ranger stay running when cold?

Hey guys, To confirm the IAC valve next time it does it turn engine off then lightly tap the flange of the IAC valve with a small hammer. Not to hard and only on the flange. then restart the engine if your tap was enough it usally will restart normally. Then you know the IAC valve is sticking.

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