Well this is my first post here on these forums. Yesterday afternoon I bought a 1998 Ford Explorer Sport with the 4.0L SOHC engine and an automatic transmission from a private party in my state. The reason they were selling the vehicle is because of this very problem- they couldn't afford to figure out what the problem was and have it fixed.

The problem explained... when the engine is cold, it works perfectly fine. The idle is perfect, it sounds good, it accelerates as it should, etc. Once the engine warms up, however, it can stall when approaching a stop sign, light, etc. After the engine has stalled, you can put it in park, turn the ignition key off, turn it back on, and the engine will fire right up (immediately with zero hesitation). At this point it is idling as it should and acting just fine. But when you go to put it in drive, it shuts down. I even tried double footing it so I could rev the engine up a little bit to see if that would help, but it simply shuts down... just as if I had turned the key off at the very moment I get the shifter lever in drive. Now here's the weird part; if I put in reverse, 1, or 2, it works just fine. There are no problems whatsoever in any of those gears. The only time it will stall is if the vehicle is in drive. From a stop, I was unable to get the vehicle to move in D after the engine was warm. To get it on the trailer, I simply put it in one of the other gears and drove inside the trailer after I bought it.

Any thoughts as to what might be causing this issue?

Thanks for any and all help.


-TomCat

 

Does it stall if the engine is allowed to heat in place and stationary, then a drop into drive? Or does it require the vehicle to be driven to the point of stalling? Does it seem to just lack power, or does it seem to be the (TCC) torque converter clutch dragging it to a stall?

Still stall in drive with the trans range sensor unplugged during an event?

 

Thanks for the response. Answers to your questions:

It doesn't seem to do it if it warms up parked from what I have seen. It doesn't seem to be lacking power at all, nor does anything seem to be "dragging" it to a stall. The engine just shuts off as though I had turned it off with the key. How do I go about disconnecting the trans range sensor?

I did some more testing today. After I fixed some other things on the car, I pulled it out of the garage and let the engine warm up (it's 12 degrees F outside according to the temp gauge). After the engine had been running for 15-20 minutes, I tried it out. From park to drive was fine... no stall. I then took it out for a spin. I took her up to around 50-55mph and came to a complete stop about 1.5 miles from home... no stall. I turned around, put it in reverse, backed, up, and tried putting it in drive again... no stall. I drove another mile or so, turned around, and it stalled that time (roughly 2.5 miles from home). I then put it in neutral, fired it back up, put it in drive, and it stalled. The engine just abruptly stops as though the ignition key was turned off. So I put it in 2, got it completely turned around, and got it up to about 10-15mph at which point I shifted into drive- it ran just fine. Pulled up to a stop... no stall. It didn't stall again until I tried turning around about 2 miles after the first time it stalled. This time, I started it in neutral and pressed the overdrive button to turn O/D off. I shifted to drive and it didn't stall. I then headed for home (after turning O/D back on) and it stalled turning into my driveway. I put it in neutral, pressed the O/D button again, but this time it stalled in drive. I had to refire, shift into 2 and get moving before I could get it in drive again.

Hopefully that provides some insight to my problem.

Thanks again! I hope we can get this figured out.

 

When your coming to a stop, and it starts to stall does it 'shudder' at all? or does the engine just shut off smoothly? Has it ever stalled at any cruise speeds, or out beyond the first shift? When it starts it stall cycle (stopped), try raising the RPM's to about 1500 and drop it into drive.. See if it shakes or shudders, or has an abnormally harsh engagment..

 

It didn't at first, but I just took it out for another drive (this time a tad longer and at higher constant speeds). It did what I would consider a "shudder" when it stalled both times on that drive. It also did it when I stopped at my mailbox (hadn't even started turning into my driveway). It shuddered as the idle slowly dropped off.

What is weird is that turning over drive off usually allows me to put it in drive after a stall. 3 out of 4 times, I'd say. Other times I can get it into 2 to get moving and then shift it to drive and continue driving.

It has never stalled while cruising or beyond first gear. It only stalls at a very slow speed or when the vehicle has stopped. Pressing the accelarator doesn't seem to have an affect... the engine still stalls and shudderes now.

EDIT: It doesn't always stall, though. For example, it didn't stall after I drove back to my house, stopped at the garage door, and pulled into the garage.

 

Pardon the double post, but I wanted to add that it doesn't shudder when it stalls the second, thrid, etc. time after it stalled the first time. It only shuddered the first time it stalled... if that matters at all.

 

How was your problm fixed? I'm having the same symptoms.

 

I have a 2002 Ford Explorer Sport and have been having the exact same problem listed above. I've had this car about 6 years and it has 154,000miles and I've had no major problems. I've had a mechanic look at it and found nothing wrong with the battery, alternator or fuel pump. He replaced a fuel hose thinking that would fix the problem. But I have since stalled on the highway. To me, the stalling seems to be random, or at least after the car has been on for a while, and always shudders when coming to a stop, then the engine shuts off. The car will always turn back on, but immediately shuts off when put into drive.
Any suggestions would be appreciated.

 

Hello, I was having the exact same problem you are describing and I took it to a reliable mechanic who said it was not the fuel pump, but possibly due to a leak, so he replaced a fuel vacuum hose. That did not solve it. Then we took it to the Ford dealer we bought the car from, they replaced the IAC...and that did nothing. But finally they were able to have it stall on them while they had a computer hooked up to it, and were able to diagnose the problem. They replaced the torque converter valve? I hope I named that correctly. But I have been driving 30 miles to and from work for 5 days now, and no stalls. Hope that helps someone....it cost me $583 to solve
Dont take your car to a dealership if you dont have to!

 

Greetings Fellow Idle Stallers,

I recently ran into similar symptoms and fixed it on a 2000 Explorer Sport Track.

The symptoms in short:
At idle the engine would drop in RPM and then recover or it would drop in RPM and die (stall).

Fix in short:
Clean throttle body around butterfly thoroughly.


The symptoms in Long:
This was only happening under all 3 of the following conditions...
1. Engine warm and in low idle mode.
AND
2. Car in gear R, D, 1, 2. Not an issue in P or N.
AND
3. A/C on or Defrost on.

Fix in long:
Unlatch top of air cleaner box, unplug MAF sensor, loosen hose clamp where intake hose meets throttle body. With care pull off intake hose and set aside. You should now see one big butterfly valve in the throttle body. Inspect for dark (black or brown) colored build up around the butterfly and where it meets the housing in the idle mode (nearly closed). It does not take a lot of build up to cause this problem. Remove 4 bolts from the throttle body and clean both sides with a clean rag. Make sure to hold the butterfly valve in the open position and clean the edged of the flat round butterfly valve and all around the housing. Give it the white rag inspection making sure it is perfectly clean. Reassemble, let the engine warm up and test idling in gear with defrost on. Problem should be fixed.


Fix explained:
The stall at idle symptoms had been occurring for months, first noticed when the AC was on. Later, the check engine light came on and produced an EGR low flow code. After testing all EGR components, IAC, TPS and any other system related to the idle function of the engine's computer, they all tested good but the problem persisted. Then inspecting the the throttle body there was a little build up. Once I cleaned that thoroughly, the symptoms went away.

When the engine is cold and first started, it goes into a high idle setting until the engine coolant is up to operating temp. While in the high idle mode, the engine RPM are high enough to compensate for the load of the transmission being in gear and the A/C pump turning on (even when the throttle body has minimal blockage). In warm or low idle, there is little margin for error, in this mode the butterfly valve is just barely cracked open and the IAC is not compensating for a cold engine. The computer reads sensors to know the engine temp, if in gear, if the power steering has a load and if the A/C pump turns on. Knowing the status of such items the computer will take action to increase the idle to compensate for the various loads, this is generally through activation of the IAC or Idle Air Control valve that allows air to bypass the butterfly valve in the throttle body, thus increasing RPM.

I found that testing with the engine in gear and the Defroster on was best as defrost mode cycles the the A/C pump more frequently. With the top of the air box loose I could hear the the IAC make an adjustment a split second before the A/C clutch would kick on. It make a light thump echo audible with the air box top loose and lifted a few inches. Just after the the IAC thump, the A/C clutch tries to kick on but drags the RPM too low and the computer turns off the A/C clutch till the next duty cycle. In this case when the RPM dropped it would sometimes recover and sometimes stall. Your symptoms may vary depending on how much buildup is in the throttle body / butterfly valve.

Happy Idling,
Green Lantern