Hello all,

I still have my 2003 Expedition now with 307k on it.
5.4 Triton 2 valve
17 mpg

About a week ago with the engine warmed up a-plenty and while cruising along at 45ish the truck started to jerk as tho I was doing small neutral drops.
That happened three or four times and I was able to nurse it to my mechanic.
Of course I had not shut it off en route. The check engine light had come as soon as it acted up so they hooked it up and determined it was a bad coil pack and recommended that they replace the bad coil pack, all spark plugs, all boots, and the fuel filter.
They then cleared the code and I drove home with a few neutral drops.
Note the check engine light was solid, not flashing. I don't know the code.
A few days later I drove it back to the mechanic for the above repairs and on the way it did its N thing a couple of times.
When the repair work was done I drove it home and, on the way, I was at a stop light and the engine simply stopped.
I threw it in N and cranked it. Nothing. I cranked again three times and it finally started (kind of like a flooded carb used to clear up)
A mile later, while cruising home it repeated the neutral drop thing mentioned above.
Note that the check engine light did NOT and has not come on since the first version.
Back to the shop in a few days and they discovered nothing ....but on the way there, while at cruising speed, it did the neutral drop thing a few times.
Coming home again after the mechanic inspected his work and took it for a test run...I am at a stop light, and again. The engine stopped.
Again I put it in N and cranked it and, three cranks later, it started.
It seems as though if this happens (sporadically) while I am cruising along the engine restarts itself...kind of like in the days of old when you could push start a car with a manual trans by pushing the car and then letting out the clutch.
BUT...if it happens while stopped and idling, the engine just quits as there is no inertia to get it started so I have to rely on the starter motor.
It's pretty scary when this happens when stopped and waiting to get into fast traffic. When the same thing happens while at speed, it seems to just correct itself without putting it in N and cranking. It burps, the engine probably stops and the starts again on its own before I have a chance to even react.
Also, again, since the mechanic cleared this error code and shut off the check engine light, the check engine light has NOT come on...either before or after the new coil, plugs, boots, and fuel filter.
Also, this has only happened when the engine and trans are completely warmed up.

So, in about 100 miles it has done the neutral drop thing about 9 times and the complete engine off thing twice.

For now I am going to continue to drive it to see what develops. I think I will get it back to the mechanic to see if it will act up while there for an afternoon of testing.

Ideas are welcome and appreciated.

 

A dirty fuel filter or failing fuel pump perhaps?

 

Are you the original owner ? Has the has the fuse box ever been replaced ? Has the fuel pump been replaced ? The '03 - '04 Expies are notorious for fuel pump relay failures. That relay is soldered to the circuit board in the fuse box. Tell them to do a fuel pressure check at the fuel rail schrader valve. You should see 45 - 55 psi of fuel pressure..

 

As a "solution" to this current problem, the fuel filter was replaced last week just after this developed and the engine stuttering continued to fail after the replacement.
We have owned the car since 100k
The fuel pump was replaced 50k miles ago
I replaced the fuse box about 60k ago in 2021-ish because of the exact fuel pump relay issue you mentioned. That relay had, indeed, failed. Replacing the fuse box fixed that.
Back then that fuel pump relay caused the engine to stop and it was similar to the current problem HOWEVER if it stopped while I was driving the car shut down and I drifted to the side of the road...wait 30 seconds with all things dead, say a prayer, and it started.
This time if it does anything while I am driving down the road the engine restarts itself within a few seconds.

I will check the pressure idea and welcome any more! Thank you!

 

Thanks for the response.
I just changed the fuel filter this week...no change in the problem.
The fuel pump was changed 50k ago.
Always use the same mechanic...and he is an Expedition guy.

 

This! ☝️ Symptoms sound exactly like a burnt failing relay. Low engine RPMs seem to cause the greatest resistance/heat in the relay. When mine failed, it always shut off stopped in traffic or at a light. I could see cruising at low engine RPM like 45 MPH in overdrive with the torque converter locked up doing this as well. Hopefully your mechanic is good with a soldering iron and willing to replace just the relay. It's about $300 cheaper!

 

OK...I just ordered a rebuilt core fuse box...just like last time five years ago.
I am keeping my old core and will replace the relay when I have time. I am not very good at soldering and I need to get rolling...I can explore my soldering skills when I have more time.
I think you nailed it with your diag that it was this relay. Plenty of others on line have echoed this issue.
Freaks me out that the thing just stops...then starts within a minute. Does not seem that it has enough time to cool down and function but, apparently, it does.
It has done this about 9 times while under sail and twice while stopped at a red light. It's my only car so I will wait till the package arrives and simply not drive till then.

For the record: anyone dealing with this same problem:
1) Make sure you disconnect the battery before you start tearing your fuse box apart
2) Be very meticulous with how you transfer the fuses and relays from the old unit to the new unit.
3) For the record, my 2003 Expedition went 250k before the original equipment relay fried itself five years ago.
It then took 5 more years (60k) before it broke again (this current issue)

Thanks everyone! I will report back when the mission is complete.

 

When mine failed, the solder blistered (Idon't know how else to describe it) away from the hottest pin. I re-flowed the solder and added a little on my initial investigation. It worked perfect while my wife drove until I could replace the relay. The original relay showed signs of over heating, but the primary issue was the soldered hint on 1 pin. I fully agree with your tip of being meticulous with the fuses. I used a piece of cardboard to trace out my fuse box and then "punched" then into the cardboard as I took them out. My tip: buy a solder sucker to help remove the old solder when replacing the relay.

 

OK...finally figured it out:

It was the crank shaft sensor.

At the beginning of this the mechanic replaced the plugs, the fuel filter, the boots, one of the coil packs (which threw a code) (and prompted the replacement of all this stuff anyway...as they all needed attention).

However, while all that stuff needed to be fixed anyway, replacing them did nothing.
Sporadic engine failure persisted.
I was then convinced it was that fuel pump relay so I ordered a rebuilt fuse box and installed it myself.
Ten miles later, persistent, sporadic engine failure...again and NO ":check engine" lights.
Then, last week, the engine stopped at an intersection and I cranked and cranked for about a minute. It started but this time the check engine light was on (woo hoo!)...so at least something was registering in the brain.
Back to the shop and they determined it was the crank shaft sensor.
That was replaced...they drove it around town for a day and it works like new! No engine failure, no misfire, full power.
NOTE: During this entire episode my fuel consumption was never off. 17MPG
OK...see you next time. THANK YOU everyone for your suggestions and help!

 

Thank you for following up to close out the mystery!