This article today saved me a tow and a service call... instead I just bought the part, and fixed it in the parking lot at work.

 

Thanks for such a prompt and informative reply!! I'll jump right on it and see what I can find. Thanks again.

slbdives

 

No problem, but you replied to the wrong thread. No biggie though.

Good luck.

 

I have a '95 explorer with over 160,000 miles on it. I have replaced my IAC from www.rockauto.com. I have yet to solve my problem of bad idling. It never idles bad when cold. Only after it has been driven for a while then it will act up. Sometimes it will act like it is going to die but will not. Sometimes it will stall out. If you let it sit for about 30 mins then go back out and start it. It will act like it is going to die and idle at like 500 rpm. I am out of ideas. I have replaced spark plugs, wires, rotor, IAC, and filter. The next thing I want to replace is the fuel filter. But anyone have any ideas. Thanks.

 

150K, welcome to FTE.

Since it idles OK until it warms up and goes into closed loop, I'd look in that direction. Maybe first change the thermostat, and then look at the temperature sender being bad. Your model may have 2 senders, one for the temp gauge and the other for the PCM. The PCM sender might be at fault....???

What about trouble codes, are any present?

 

Thanks for the reply. No Check Engine Light comes on. I have replaced the IAC, Therastat and all hoses and temperature gauge sending unit. I drove the car all day and ran great. I get home let it sit for about 30 minutes then acts up again. It spudders and acts like it is going to stall out and actually did. Keep in mind I am still in park and not in drive yet. I finally pushed the accelerator and gave it some gas and ran fine. I go to the store and it does it again. The engine shakes and acts like it is going to die. But runs fine once you get going. I have replaced so many parts that it is irritating. What does the PCM do? Sorry newbie here. I have been dealing with this problem for a year now and it just seems like it is getting worse.

 

150K, the PCM is "powertrain control module", and it's the computer that controls many engine and transmission functions. Also known as "computer" or "engine control module".

There may be two coolant temp sensors on your model. One is for the gauge, and the other gives temp info to the PCM. That's the one (PCM) that would affect the engine idle. It's the one with the gray plastic body and two wire connector. (The gauge sender is brown or tan). You can test it by measuring resistance between the two sensor terminals. It should read 40K-41K ohms at room temperature, and should decrease as the engine warms up.

The only other thing that might relate to your problem is a dirty throttle body. It's easy to clean, just remove the intake air tube, and clean the carbon off the area where the throttle butterfly contacts the housing. Use a throttle body cleaner and a shop rag. Don't use a harsh cleaner, because it will remove the coating on the throttle body. Good luck and let us know what you find......

 

Thanks a bunch for your reply. I am going to mechanic this weekend and taking all of this information with me. I have yet to see what is going on with this truck. But it seems if it cold out it runs great. It is cold here in Missouri and now my truck has stopped acting up. Any ideas why? Thanks again.

 

After reading your thread, I did a little research on my 94 limited with 225,000k and replaced the IAC ($60.00) and it looks like the problem is taken care of. Thanx for your indepth thread. My father is a retired auto shop teacher and he is really going to like this site. Thanx again, Bo

 

1999 Explorer XLT 4X4 just replaced the IAC for a rough idle when cold (no testing just decided to shotgun it). It did NOT correct the problem.

Does the computer have to be reset for the new IAC to work properly?

My new IAC came with a gasket. I choose not to use the gasket cause the old one did not have one. Are folks using the gasket or not.

Thanks,
John

 

Please let me know if you find out anything. I changed the iac and am still having the same problem with the idle at start. Still, with 225K and still getting the same gas mileage as when I bought it. I'll put up with a little rough idle at start up. Just hope it passes CA smog next year...

 

My X is shot. It is in the shop for a blown water pump. Damn this Car

Well I will keep you updated. Still working in the rough idle problem.

 

Could this be the IAC also? My sons 98 Explorer wont idle properly when its cold..it goes from 1500 rpms down to about 500 and will usually die out.Once the engine has warmed up,it idles perfectly and runs great,it only idles strange after the vehicle has sat and had a chance to cool down.

 

Well guys got the water pump fixed and I am still having the same trouble. I was hoping that maybe someone had an answer for my cold idle problem. Any answers would be great. Thanks.

 

shot in the dark - haven't read the previous posts but wondering if you might try this: warm up vehicle, turn off, disconnect electronic engine temperature sensor and start it up again. see how it runs, maybe remove it and check the resistance between the terminals vs. temp and make sure it behaves as it should. I had one of these things go on me - would stall after stepping on the gas at a stop light - until I disconnected it and it ran perfectly when warm (ie/ the sensor should give almost infinite resistance (very high) when warm - that's why the engine doesn't puke when it's warm).
Don't know where you live but would make sense for a temp sensor problem to be detected when the weather starts getting colder. I found mine last november.