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Engine shuts off while driving without warning?

Tiny
TECH2020
  • MEMBER
  • 2005 FORD EXPLORER
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 99,300 MILES
Once in 2007 and now twice in 2019 the engine of my SUV shut off without warning while driving. Extremely dangerous! In all cases I was able to get to the shoulder and the engine restarted and ran like nothing happened. This last time I recall seeing a message on the dash about "Check Fuel Cap" but this may not be related to the problem at all. Where should I look first? I would like to know if it is fixed if I make repairs but not if a "not fixed" results in getting hurt of killed. Maybe a different car is the answer.

Thanks!
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Tuesday, September 10th, 2019 AT 10:47 PM

48 Replies

Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

I have checked for any recalls or Technical Service Bulletins for anything regarding this problem and didn't find anything. A problem like this could be caused by a wide variety of things, so all I can really do here is attempt to point you in the right direction and go from there. So this could be an intermittent problem with the Crankshaft Position Sensor(CKP) or the electrical connector or loose wires from the CKP to the Power-train Control Module(PCM) or "computer". In the diagrams down below I have included a description of the CKP sensor, a wiring diagram of the CKP circuit, the location of the ground wire for the RF shielding, and a guide for tracking down poor electrical connectors and intermittent problems in an automotive electrical circuit for you to go through. Please go through these guides and check the CKP circuit for an intermittent problem and get back to us with what you are able to find out. We can go from there.

Thanks,
Alex
2CarPros
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Wednesday, September 11th, 2019 AT 4:17 AM
Tiny
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Thanks Alex so much! I will review the information you sent and let you know what I learn.
Tom
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Wednesday, September 11th, 2019 AT 5:44 AM
Tiny
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Alex, I started looking at the schematic images you posted (I have electrical experience), I went to zoom on them so I could read the writing but the resolution is kind of bad. Any chance the wiring images could be of higher resolution?

Thanks- Tom
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Wednesday, September 11th, 2019 AT 6:10 AM
Tiny
BMDOUBLE
  • MECHANIC
  • 1,139 POSTS
Alex is absolutely correct, if I could add something from a clue that you gave us about the fuel cap light. On a rare occasion I have had the fuel tank pressure sensor short to vref which will cause the power-train control module to shut down. The vref circuit is a 5 volt circuit that several sensors use as a reference to for proper sensor voltage feedback. The fuel tank pressure sensor tells the power-train control module how much pressure is in the fuel tank, when the PCM tells the purge valve to open and pull a vacuum on the tank, the voltage will go from 2.65 to 1.50 approximately. And when the sensor fails, it usually fails high at 5 volts so now the PCM thinks that the fuel cap is off because the voltage is not coming down when a vacuum is commanded. Throttle position sensor, dpfe/egr sensor, fuel tank pressure sensor, are some of the most common vref short failures that I have seen. This is only one scenario, but if the vehicle will not start, probe the brown with white wire for 5 volts with the key on at any of those sensor connectors, or just unhook them in a no start condition to see if it starts. And if you have a scan tool that can look at the sensor readings, the ftp should read 2.65v with the key on engine off.
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Wednesday, September 11th, 2019 AT 7:49 AM
Tiny
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Okay, I located the CKP. The harmonic balancer was repaired a few years ago if that matters. The sensor is very greasy since there is a slow oil seepage from one of the bearings on the engine front. I could not easily get to the wires of the sensor, it is harder to access than expected (no lift, ramps, etc). Would the failure that caused the engine to stop show in the error codes? I think I can read them or I would get a parts store to do that.
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Thursday, September 12th, 2019 AT 6:05 PM
Tiny
SCGRANTURISMO
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Hello again,

This type of failure should throw a Direct rouble Code(DTC), but not always. If you have a code reader it should be fairly straight forward on pulling the codes. Here is a link explaining how to do that:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

If you don't have access to a code reader than you can go to your local auto parts store, like AutoZone and they will read them for free. Please get back to us with what the codes are and we can go from there.

Thanks,
Alex
2CarPros
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Thursday, September 12th, 2019 AT 11:48 PM
Tiny
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Great, I should be able to get to a parts store in the next few days and I will ask them to do a code read. The engine light has not come on, would that indicate a DTC was not thrown?
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Friday, September 13th, 2019 AT 6:42 PM
Tiny
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Hello again,

The Malfunction Indicator Lamp(MIL) or "check engine" lamp is illuminated when a Direct Trouble Code(DTC) is set. It will be flashing when a catalyst damaging DTC is set. When you turn the ignition key to "RUN" the MIL should light up, and if there are no DTC(s) set, turn off. This is known as a bulb check to make sure the bulb is working. So if the MIL is not illuminated then there is no DTC set.

Thanks,
Alex
2CarPros
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Friday, September 13th, 2019 AT 11:47 PM
Tiny
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Thanks Alex, I guess I`m back to square one. I`m going to examine again getting at the CKP but it seems in a tight spot, it will be hard to determine an intermittent electrical connection with little room to work. If I knew the CKP was the problem I`d really go after it.
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Saturday, September 14th, 2019 AT 6:05 AM
Tiny
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Alex, I spoke with a family member that has extensive experience with Ford Mustangs. He stated he had a similar issue to mine with the engine suddenly shutting off without warning. What fixed his was replacing the alternator. To me this seems an unlikely cause for my Explorer failures by I wanted to run it by you. I did just replace the alternator about 9 months ago.
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Saturday, September 14th, 2019 AT 8:10 AM
Tiny
BMDOUBLE
  • MECHANIC
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Bad alternator diodes can induce noise in the system and corrupt the crank sensor signal. Have replaced tons of alternators for this at my dealership, most of the time with no codes present or a code in continuous memory with no light on.
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Saturday, September 14th, 2019 AT 9:05 AM
Tiny
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Thanks BMDOUBLE. I replaced the alternator last fall, got a cheap one from China through ebay. Is the source of significant concern? Does it really make much difference?
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Sunday, September 15th, 2019 AT 12:24 AM
Tiny
SCGRANTURISMO
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Hello,

Actually, yes it does. Hat old adage you get what you pay for. It is as true today is it has ever been. I would stick to Motorcraft (Ford), Delco, Denso, Bosch, or manufacturers of this caliber for replacement parts. There is a reason that vehicle manufacturers sub contract to companies like these for parts such as OEM fuel injectors, O2 sensors, and others. BM Double is very knowledgeable when it comes to the Ford Brand so you might want to check into this and get back to us with what you find out, please.

Thanks,
Alex
2CarPros
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Monday, September 16th, 2019 AT 3:03 AM
Tiny
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Yes sir, Motorcraft seems to be the best choice for alternators and not just because I'm a Ford guy, but because I've had to remove literally hundreds of customers' aftermarket alternators (brand new) because they did not work correctly.
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Monday, September 16th, 2019 AT 6:06 AM
Tiny
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Okay, is a re-manufactured Motorcraft okay, or does it need to be new? The new is quite expensive.
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Monday, September 16th, 2019 AT 10:23 PM
Tiny
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Re-manufactured is good.
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Tuesday, September 17th, 2019 AT 7:51 AM
Tiny
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Today, 9/22/2019 I had a Motorcraft re-manufactured alternator installed in my vehicle listed above. I will update here if/when the sudden engine stop happens again, or maybe to give an update on how it is going. Thanks everyone for your helpful suggestions, you are very appreciated!
Tom
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Sunday, September 22nd, 2019 AT 2:16 PM
Tiny
BMDOUBLE
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Awesome! Youa re welcome!
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Monday, September 23rd, 2019 AT 9:03 AM
Tiny
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Hi Everyone.

It is (12/15/2019) almost 3 months since installing the Motorcraft alternator, so far no engine sudden stop.
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Sunday, December 15th, 2019 AT 1:10 PM
Tiny
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Excellent!
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Sunday, December 15th, 2019 AT 2:02 PM

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