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6Bucs, Ford Senior Master
Category: Ford
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Experience:  Ford senior master tech, 18 years experience.
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Ford Explorer: lose power..stall..medium grade hill at approx 60 mph

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Why does my Ford Explorer lose power and then stall after experiencing a mild load (driving up a low to medium grade hill at approx 60 mph)

6Bucs :

Hello, James here. Let me ask you a couple of questions first. How many miles on the engine and how well maintained is it? Secondly, after the engine stalls, does it start right back up? Does the check engine light come on, flash, etc? And is your explorer equipped with automatic trans? Thanks. This will help us narrow your problem down.

Sorry, I see now you already said the engine starts right back up. Sometimes the website is slow on our end and does not load the 'already tried' until we have posted response. Let me know on the other items, and we can continue.
Customer: replied 5 years ago.

I just bought the car, but it appears to be in excellent shape with almost all of the accessories in working order. Weatherstripping looks in excellent shape making it seem like it's been garaged for much of the time. There are at least 150K miles on the truck with the ODO frozen at 141K (probably the result of a recently broken worm gear since speedo is still functional). The engine compartment appears to have been steam cleaned, but there are no visible leaks on the underside of the chassis. Ball joint boots are torn, but ball joints seem to be working well anyway.


There are no check engine lights and an OBDII reader showed no error codes when read. Emissions status is green based on the reader. The secondard cat convertor appears purple in color, but not sure if this is normal. The car is equipped with an automatic tranny which seems to be functioning well. Tranny fluid looks clean, but was significantly over-filled. This was corrected today by suctioning fluid to the proper level.


I'm suspecting either the fuel filter or the fuel pump at this point, but want the advice of someone who's seen many Explorers with this problem. Just before the stall the vehicle was performing slugishly. Engine temp seemed a bit high, but nowhere near the red--maybe 1/3 up the scale. My almost exact '95 Explorer ran cooler. Many thanks for your help! Hope that gives you more info!

Okay. For your explorer there are a couple of things which can cause a stall after a drive like you describe that will most likely not set a code. The first thing to check is for a sticking EGR valve. There is a chance the valve could have stuck open and stayed that way until you came to a stop, caused the stall, and then reset due to the vibration caused by the stall and the lack of exhaust pressure after the engine stops running. You can remove the valve fairly easily to inspect for buildup inside and clean with carb cleaner, or replace as necessary. The second likely cause is a sticking torque converter clutch in the transmission-common on the explorer, but less common than the EGR valve. This is caused by the friction plates in the converter expanding over time due to heat and contaminants. This is a little trickier to diagnose yourself and a more expensive repair, obviously. The converter clutch, like the EGR valve, can come on once you're at speed, and if it continues to hold when you come to a stop, works just like a clutch on a manual trans in gear with your foot off the pedal. Once the engine stalls, everything works great again until the clutch sticks again. Since the EGR valve is much easier and cost effective to inspect and clean and because the engine seemed low on power right after that for a bit, I'd go that route first and see what you find.

By the way, changing out the fuel filter at that mileage isn't a bad idea. In theory, it's possible there is an issue with sediment in the tank, which could possibly make it into the filter...if it could get past the filter in the tank....but not really something we see in the field. You can try one of the trans additives too, which may help out if the converter is the issue. Less intrusive and least expensive first, right? If you need diagrams of any of these parts, feel free to reply back here.


Customer: replied 5 years ago.

Hi James,


Great knowledge and advice. I would greatly appreciate it if you could please send me diagrams if you have them (to [email protected]). One other possibly unlrelated symptom, is HOT air blowing throught the vents even when the climate control is set to the lowest settting and on vent. This may be a heat blend control door or accuator or something else related perhaps?


I do a lot of my own work so diagrams of the fuel pump, EGR valve, and heat blend door + acuator would be really helpful. As a home mechanic, I grately appreciate your approach to inspect, test, repair the least expensive and easiest to access first.


The mechanic who works at the local auto parts store is convinced that my (secondary?) catalytic convertor which is showing purple in colour was melted inside due to bad O2 sensors which have since been either replaced or bypassed. I would hope that the OBDII reader would pick this up though?? A smog test which is due very soon (early Feb) will also probably pick this up I would think. Note the fumes from the exhaust don't smell worse than normal, nor does black smoke come from my tail pipe, nor are there any large black soot deposits present on or around my tail pipe.


I work 9 to 5 so I won't get to check out any thing until Saturday. Also, if you have a recommendation for a replacement part for the rear JBL subwoofer it would be the "icing on the cake" as they say...


I'm VERY impressed with your knowledge, especially since I've owned and worked on an exactly similar 1995 Eddie Bauer Explorer since it was new from the dealer (my son drives that one now). Once you reply again with the answers from above, I'll be more than satisfied!







Hello again. The EGR, or exhaust gas recirculation, pulls exhaust gas from the manifold and routes it back into the engine to reburn it for emissions compliance. The only problem is that the engine does not run well on reburned, hot, exhaust gas. The EGR only comes on at a time when the driver should not notice it and is not demanding full power from the engine. Here's an excerpt from Ford.

EGR flow rate is determined by monitoring the pressure across a fixed metering orifice as exhaust gasses pass through it. The DPFE system monitors this flow across the orifice by supplying the DPFE sensor with a pressure signal before the orifice (upstream pressure) and a pressure signal after the orifice (downstream pressure). The DPFE sensor then evaluates these two pressure inputs and determines the pressure difference across the orifice. This pressure difference translates to a specific EGR flow which the DPFE sensor signals the PCM by an analog voltage signal. This signal to the PCM increases linearly as the differential pressure increases. The PFE system, unlike the DPFE system, has only one pressure signal input (downstream) and must rely on the PCM to indirectly infer the upstream exhaust pressure in order to determine the EGR flow rate. The PFE sensor transmits an analog voltage signal which decreases linearly as EGR flow increases.

The PCM optimizes the EGR flow rate by varying the EVR duty cycle using the feedback signal the PFE or DPFE sensors provide.


One sec, while I grab more schematics...

Torque Converter

The 4R44E/4R55E uses a four element torque converter. The converter contains the standard internal components (turbine, impeller, and stator) for transfer of power and multiplication of torque. It also utilizes a disc type Torque Converter Clutch (TCC) for maximum fuel economy.

The operation of the main torque converter components is as follows:

  • The converter cover and impeller are connected to the engine crankshaft. Rotation of the cover and impeller by the engine crankshaft sets the fluid in motion.
  • The turbine reacts to the fluid motion from the impeller, transferring rotation to the geartrain by way of the turbine shaft.
  • The stator redirects the fluid going back to the impeller, from the turbine. By directing fluid back to the impeller in the same direction as engine rotation, the stator multiplies engine torque.

When applied, the TCC provides a mechanical link between the converter turbine and the engine, allowing for a direct mechanical power transfer from the engine to the transmission. The converter clutch pressure plate is applied and released by fluid pressure, which is controlled by the Powertrain Control Module (PCM). The PCM controls the torque converter clutch using a pulse-width modulated TCC solenoid.

Torque Converter Assembly

ItemPart NumberDescription
1 - Cover (Part of 7902)
2 - Thrust Washer (Part of 7902)
3 - Converter Damper Plate (Part of 7902)
4 - O-Ring (Part of 7902)
5 - Turbine Assembly (Part of 7902)
6 - Thrust Bearing (Part of 7902)
7 - Thrust Washer (Part of 7902)
8 - Snap Ring (Part of 7902)
9 - Reactor (Part of 7902)
10 - One-Way Clutch Assembly (Part of 7902)
11 - Thrust Washer (Part of 7902)
12 - Thrust Bearing (Part of 7902)
13 - Impeller Assembly (Part of 7902)

Impeller and Cover

The impeller sets the oil in motion and directs it to the turbine. The impeller is welded to the converter cover.


The turbine is the driven member of the converter. It is driven by oil from the impeller and transfers the hydraulic power to the transmission. When the converter lockup clutch is engaged, the power is transferred mechanically.


The reactor is equipped with heavily curved vanes and its center hub has an one-way clutch which prevents the stator from rotating opposite to the engine rotation. The reactor reverses the oil and returns it to the impeller in the direction of impeller rotation. The one-way clutch prevents the force of this fluid from turning the stator against the impeller and turbine.

Torque Converter Clutch (TCC)

The clutch is joined to the turbine by means of the externally splined hub of the turbine and also internally splines within its own assembly.

When engaged the clutch friction plate bears against the inside of the converter cover. Thereby producing a direct mechanical connection between the pump housing and the turbine.

The reactor one-way clutch is built into the reactor (stator) and prevents it from rotating opposite to engine rotation.

Torque Converter Clutch Operation Test

This test verifies that the torque converter clutch control system and the torque converter are operating properly. Perform the test as follows:

  1. Connect tachometer to engine.
  2. Bring engine to normal operating temperature by driving vehicle at highway speeds for approximately 15 minutes in (D) range.
  3. After normal operating temperatures are reached, maintain constant vehicle speed of about 80 km/h (50 mph). Release throttle for about two seconds then reapply throttle to previous setting.
  4. Engine rpm should increase when throttle is released and decrease in about five seconds (converter engagement) after throttle is reapplied. If this does not occur, refer to Torque Converter Operation Concerns on the Diagnosis by Symptom Index.

3. Visual Inspection

  • Vehicle modification
  • Electronic add-on items
    • Air conditioning
    • Generators (alternators)
    • Engine turbos
    • Cellular telephones
    • Cruise controls
    • CB radios
    • Linear boosters
    • Backup alarm signals
    • Computers
  • Leaks - Refer to Special Testing section.
  • Proper linkage adjustments - Refer to Section 07-05.
  • These items, if not installed properly, will affect powertrain control module or transmission function. Pay particular attention to add-on wiring splices in the powertrain control module harness or transmission wiring harness, abnormal tire size, or axle ratio changes.
  • After a road test, with the vehicle warm and before disturbing any connectors, perform the Quick Test using Rotunda Super Star II Tester(NNN) NNN-NNNN or New Generation Star (NGS) Tester (007-00500) or equivalents. Refer to the Powertrain Control/Emissions Diagnosis Manual, Explorer (OBDI) or Ranger (OBDII).

4. Check Technical Service Bulletins and Oasis

5. Perform OBD Diagnostic Procedures (KOER, KOEO





For your climate control concern, can you tell me if your explorer has manual knobs for the control head, or electronic automatic climate control?


Customer: replied 5 years ago.

Wow. You have access to an amazing amount of knowledge. I'm now thoroughly impressed and will recommend Just Answer to other people that I know. It's well worth the money!


The climate control control on my Eddie Bauer is the electronic type with NO manual clock-type knobs. It has only a digital temperature reading, a red button, a blue button, an "auto" button, an "off" button and a verticle fan speed control dial at the far right of the head unit underneath the radio. On the bottom row of buttons there are a Max Air, Vent, Floor(?), Defrost, and another button that I can't recall at the moment. I'm assuming it requires an electronic heat blend control door and/or accuator of some type, but I'm not sure. I have no idea where to find these parts though or the best (only?) way to access them. I also need the part numbers if you happen to know them as I think many different types can be found on ebaymotors. Do you happen to know if it's it a difficult job to replace these? I've changed transmissions, radiators, brakes, master cylinders, ball joints, and engines so there's not too much I'm afraid of at this point. Still, some tasks are a whole lot harder than others!


Many thanks for any help you can give me!!

Ok, so there are some pretty vague testing procedures for your temperature blend issue, but all of the failures we see are either the blend door actuator, or a broken blend door inside the air distribution chamber. You can remove the electric actuator and change the temp on your control head and watch for it to move. If it moves, the door is most likely broken. If it doesn't move, it's probably the actuator and we can get into that a little later on if you like. The kicker is that these components are only accessible after you completely unbolt the dashboard and pull it back a foot and a half or so.

You had asked for fuel pump diagrams. Did you want the operational system functions, or did you mean more like the electrical schematic?I can tag the wiring diagrams for you, but I need to do it from my other computer later tonight.

Also you were curious about subwoofer replacement. I honestly don't have much of an opinion on this issue, believe it or not. The factory stuff is really overpriced, so whenever I need a speaker I head on over to Best Buy. They have a computer there where you put in your year, make, and model, and it shows you what's available for each stereo component in the car. That sort of thing may be more helpful to you.

6Bucs and 3 other Ford Specialists are ready to help you
Customer: replied 5 years ago.

Thanks for your help, James. Darn. I was afraid you were going to tell me I had to completely unbolt the dash or something. I like the fact the A/C works, but I gotta get this thing to stop blowing hot air all over me! Hahaha.

If you don't mind, just in case it turns out that I need it, anything you have on the fuel pump would be really great.


I also thought you'd mention the speaker issue in terms of aftermarket so no worries there. It makes good sense. The original JBL sound system in this car sounds really great. Unfortunately, speakers just don't last forever--especially when you put them in a car.


Thanks again for all your help!

No problem. I'll shoot you a couple of fuel system diagrams later on tonight.

Thank you very much.