2000 Explorer 4.0 SOHC 113,000 miles

What do you think guys? Explorer just started acting up a few weeks ago. Starts fine but never goes in to high idle then immediately stumbles and stalls. Then its hard to start like its not getting fuel. Crank, crank, crank finally starts, then you have to manually control the throttle to keep it running. Once it's warm it seems to run ok. Took it on a 300 mile round trip ski day yesterday and ran fine on the highway. Not throwing any codes. Here is the result of the scan I did yesterday:

O2 B1S1 seems normal- fluctuating between .01 - .78
O2 B1S2 about the same
O2 B2S1 .065 - .71
Fuel Trim B1 Short term 0 - -2.3
Fuel Trim B2 Short term -1.6
Fuel Trim B1 Long term -4.7
Fuel Trim B2 Long term -5.5
MAF Air Rate 3.32 gm/sec
Timing 17.5 deg

First off I thought I had 4 O2 sensors? Am I wrong. If I have 4 tell me where they are because I only see three. One before each cat, then one after the cats. If it was the fuel pump why would it run ok once warmed up. Unless its a diaphragm or something that works after its warmed up. I did all the intake manifold O rings this summer when I was throwing lean codes. I haven't replaced the AIH or cleaned it in a while. I also did not clean the MAF sensor yet. I thought I would throw this info out and see what you guys have to say. Thanks for the help!

 

Typical symptoms of a dirty or bad AIC (Air Input Control) valve. You will find it on the throttle body.

Try cleaning it with throttle body cleaner, do not spray any cleaner into electrical coil.

 

I agree with Aquanaut, sounds like a bad Idle Air Control (IAC) which is a pretty common issue on that generation of Explorer and would certainly be consistent with your symptoms.

You probably only have 3 oxygen sensors. If the sensor 2 is located after both converters are y'd together there is no need for 4. The V8 has 4 O2 sensors, but I'm not sure about the V6.

-Rod

 

Clean with throttle body cleaner? Is that the same as carb cleaner?

 

I think the best thing to clean it with is electrical cleaner but throttle body or carb cleaner will work. you should purchase a new gasket if you can.

*you might want to clean your maf while you are under the hood. on my truck i need a tanperproof torx to remove it (2 screws) you only clean that with maf cleaner. you proably could use the maf cleaner on the iacv. the iacv is held on with 2 bolts I believe.

 

Electrical contact cleaner is typically quite a bit more expensive than throttle body cleaner and not as aggressive on carbon. The throttle body cleaner is typically formulated to not hurt the coatings on many modern throttle bodies, whereas carb and choke cleaner may attach that coating. For the $3 or so, I'd suggest you pick up a can of STP Throttle Body Cleaner. It's what I've found to attack the carbon best and still evaporate quickly.

-Rod

 

Classic symptoms of a bad IAC. Ive never had much luck cleaning them when they get so bad it wont start unless u press the gas. I paid about 40 bucks for mine at Advance about 3 years ago. I havent had any trouble since. My ranger was doing the same exact thing. Would not idle and wouldnt start unless you open the throttle a little.

 

That's what I'm starting to think. After 113,000 miles maybe I should just replace the thing. I'm going to see if I can find one at NAPA today. I did clean it and it didn't make any difference. In fact it stalled on me twice today while I was driving, which it has never done before.

 

If it was my truck. I would replace it especially after you worked on it and then it did something it never did before, stall

 

Yep, I'm going to get one tonight and put it on. I'll let you guys know what happens.

 

out of curiosity, is there a way to test that AIC? is there a range of resistance that is supposed to be present across the contacts of something? I hate throwing parts at something. The AIC for this vehicle is $93 at Autozone, $125 at NAPA.

 

KE3 CHECK IAC VALVE RESISTANCE
Key off.
IAC valve disconnected.
Note: Due to diode in solenoid, place digital multimeter (+) lead on VPWR pin and (-) lead on IAC pin.

Measure IAC valve resistance.
Is resistance between 6.0 and 13.0 ohms?

YES -go to next test NO replace IAC

KE4 CHECK IAC VALVE FOR AN INTERNAL SHORT TO IAC CASE
Measure the resistance from either IAC valve pin to IAC valve case.
Is resistance greater than 10,000 ohms?

YES IAC Electric checks good NO Replace IAC

Note! IAC can test ok for opens/short and still be defective due to shaft binding.

 

Thanks for the info. I didn't do the check, I just replaced it last night with a Autozone Wells part. Starts and idles fine now. Thanks for the help guys!