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4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

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Old 02-21-2010
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Rough Idle

My 94 4.0 Ranger starts fine and begins to idle aroung 1700-2000 then after awhile will drop to about a 1000 and run very rough and sometimes stall. A little touch to the accelerator fixes this for a few seconds and then it continues to run horribly at rest. Where do start with this idle issue? Also I found a bolt in my driveway yesterday and am not sure if it can be identified as a ranger bolt or other. It is about 1 1/2" and has a I over 109 on the head. Any ideas? I hear no new noises or running issues as of yet.

Thanks for any help.
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Old 02-21-2010
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Have you ever done or recently done a tune up?
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Old 02-21-2010
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Nope sure haven't it's due though.I thought it was possibly a sensor or Idle control unit but I'm not familiar with idle issues. I guess I'll have to give it a try though. Start with plugs, and wires?
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Old 02-21-2010
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I would also guess it's your IAC. You can try taking it off and cleaning it. I did mine a little while back and it helps a lot.
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Old 02-21-2010
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Clean your IAC to start with. I don't know if these have that coating in them so try to get a cleaner that won't strip it off.

Clean your MAF while you are at it. When you take off the MAF turn on your headlights and unhook the negative battery cable. While you are cleaning the MAF the ECU will reset and when you hook everything back up the computer will relearn it's idle. It's a start anyway.
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Old 02-21-2010
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Just curious, what does turning the headlights on do?
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Old 02-21-2010
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what would you recommend I clean it with/ I have it apart but worry about damaging it.
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Old 02-21-2010
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Quote:
Originally Posted by powerranger262 View Post
Just curious, what does turning the headlights on do?
it drains the stored power in the system that is usually used to keep the ECU memory in case of pulling the battery. Draining that power sends the ECU into a relearn mode that will make it kind of start from scratch when you put in a new clean MAF or other item like that. No sense in using the old values from a dirty MAF it it's no longer dirty right?


Clean the MAF with electrical contact cleaner. If you search it, you should find a good brand. As far as the IAC, I think there are certain brands of carb cleaner that are safe for use with a coated IAC or throttle body. I don't know if it is a Ranger problem, but I know some Mustangs of the era have a coating on the inside of the throttle bodies and IACs that can be removed with a standard carb cleaner. That's bad.
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Old 02-21-2010
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^Good to know.
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Old 02-21-2010
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well that isnt really necessary once the problem is fixed the idle will be fixed there is really no need to reprogram it in there, since its due to prolly a faulty part and not a faulty programing.
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Old 02-21-2010
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I will tell you I recently had a very bad idle problem and it was a vacuum hose causing it. But that also caused my check engine light to come on. Once I replaced it, the idle is better and engine light went off.
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