1998 Ford Explorer rough idle when cold

VERNE

MEMBER
1998 FORD EXPLORER
6 CYL
4WD
AUTOMATIC
110,000 MILES

When temp drops below 25 degrees F, car will start and begin to ldle and then stops. To insure the car will run I must feather the foot feed for a few minutes before car will idle on its own. Check engine light gives codes 0171 and 0174 (lean on left and right banks). I've replaced the IAT sensor (inlet air temp sensor), cleaned tjhe MAF sensor. What else can I do? What should I check?

Thank you.

5 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Go here and checkout our video.

https://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm

You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody
The ECT(engine coolant temp) sensor will have more control over the cold idle in conjuntion with the IAT.

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Saturday, November 1st, 2008 AT 1:06 PM

VERNE

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3 POSTS

I will give this a try. Thank you.
Verne

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Sunday, November 2nd, 2008 AT 3:18 PM

MERLIN2021

MECHANIC
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Let us know.

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Monday, November 3rd, 2008 AT 3:18 PM

VERNE

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3 POSTS

I checked for vac leaks and found none. I replaced the idle air control valve but problem persists. Engine starts, revs up and then idles way down and dies. I must work the foot feed to keep engine running until it warms up to idle on its own. Previously I had replaced the inlet air temp sensor and cleaned the Mass airflow sensor. It seems to me that this is a temperature related problem but what other sensors are temp related? Thank you.

Verne

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Monday, November 10th, 2008 AT 11:14 AM

TRYING2

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1 POST

I have a 1998 ford explore 4l sohc 6 w/60k that has the same problem. Haven't tried to fix it yet as I am mechanically challenged. In trying to diagnose the problem I read a post somewhere, not sure what site, a guy had the same problem and thinks it's the intake gasket. He said that it is possible that when it's cold the gasket shrinks causing a leak and rough idle, when it warms up it expands and no leak. I'm assuming that you warmed the vehicle up so it would idle then tried to find the leak. Sounds possible to me, but am looking for some confirmation before I try to replace it. Hoping somebody with some knowledge of this will comment.