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post #1 of 4 (permalink) Old 03-18-10, 05:27 AM Thread Starter
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1999 Explorer 4.OL SOHC idle-die issue

Greetings, its been a while since Ive been out her posting...

Ive got a 1999 Explorer Sport, 4.0L SOHC, automatic.. and for the past few months the starting has gotten progressively worse. It would crank and crank, but not fire. Once it would start, it would run fine. But once it was warmed up, it would struggled to restart.

At first I thought it was bad fuel, so I ran injector cleaner for a few tank fulls. It seemed to help for a little while, but then it continually got worse, even with the cleaner still in it.

A week ago I removed the old IAC, cleaned it heavily, reinstalled it, and it didnt make any difference.

Yesterday I installed a new IAC and it immediately made the start up better. But, after it idled for a few seconds, it immediately stalled. The only thing I didnt do when reinstalling the new IAC was put in the new gasket that came with it. I still have it, but the old one is stuck in pretty good.

This morning with it cold, it started fine, idled fine, and then I drove it to work. On the way there I came to a stop light, and it stalled on me.

Qs: Would a bad IAC gasket have it quickly die like that?

My list of possibilites is:
-IAC gasket
-MAF sensor
-TPS sensor
-EGR valve
-coil
-fuel pump
-fuel filter
-intake manifold gaskets
-PCM
-bad injectors

After messing around with this for the past two months now, Im finally ready to take it to the shop to let them run diagnostics on it. The check engine light is not on. btw: when running with constant gas on the highway it runs fine. By changing out the IAC, I suspect all Ive done is make the problem worse, or mask whatever it is...

Any input would be appreciated.

Thanks!

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post #2 of 4 (permalink) Old 03-18-10, 08:02 AM
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Re: 1999 Explorer 4.OL SOHC idle-die issue

To see if the gasket is leaking, spray around the area with the engine running. If it picks up RPMs, it's leaking. Changing it won't mask a problem. Take it to an AutoZone and they'll check to see if there are any codes. While there, get some MAF cleaner and clean the MAF. If you haven't changed the fuel filter, I'd highly recommend it.

Bert
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post #3 of 4 (permalink) Old 03-18-10, 09:19 AM Thread Starter
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Re: 1999 Explorer 4.OL SOHC idle-die issue

I just got a callback from my shop where I took it this morning...

They said the MAF was filthy, and that the IAC I just installed was faulty. They tested the IAC repeatedly and it kept coming up bad. After they cleaned the MAF and put in a new IAC, they said everything is fine, and it doesnt do any of the symptoms from when I took it in.

So after work, Im heading back to O'Reillys and returning the faulty IAC and getting a full refund.

Anyone else ever replace a IAC with a new one, only to have the new one turn out to be faulty?

Had they not ran diagnostics and done all the testing on the new IAC, I would have been scratching my head for quite a while on this one...
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post #4 of 4 (permalink) Old 03-18-10, 07:26 PM
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Re: 1999 Explorer 4.OL SOHC idle-die issue

Glad to hear you got it sorted out.

Quote:
Originally Posted by WiscExplorer View Post
Anyone else ever replace a IAC with a new one, only to have the new one turn out to be faulty?
Yes, not personally though but on a Dodge forum I subscribe to there were quite a few incidents of people buying a "new" IAC, only for it to not work. One guy (not knowingly) mentioned that the pulled on the plunger and it didn't budge. There should be at least some play, but don't move it more than 1/4" or you'll need a new one anyway. Needless to say you're not alone. Perhaps someone missed a spec over at one of them China factories.

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