2003 5.4 Periodically stumble & die. Then start and all good.

[GoMach]

I sure hope I can get some help on this one... It's Our 2003 5.4L (XLT)

SYMPTOMS:
- Will periodically stumble and die. Usually early in the trip.
- Will usually start right up and run normally (and often stay good for several days)

SEEMINGLY UNRELATED SYMPTOMS:
- The traction control has been activated on a normal day on dry pavement and I felt the pulsing of the brakes. After turning it off and restarting about 4 minutes later, NO PROBLEMS. The traction light also did come on.

WHAT I HAVE DONE:
I FIRST replaced the DPFE because one post/tube was broken. Replaced the hoses.
I NEXT checked the MAF for any debris, and used MAF cleaner.
The problem persists (if it's a little less frequent, it's not yet obviously so)
No engine light (sadly). It's NOT throwing any codes...
I tried to capture them with my BAFX bluetooth reader. Nothing.

ALSO: I'm frequently logging data while driving in case it catches something. The MAF readings look right. They did not dip just before the problem... they only dipped after the engine stumbled (such that I cannot really tell any cause/effect).

MY GUESSES:
It could be some central wiring, maybe specifically to the engine computer, OR could be the computer itself, causing one or both issues. It certainly could be two issues. But here's the problem I see... it has zero issues or stumbles until this happens, then it often takes only a restart (often turning all the way off first) to run normally. Thus, it seems electronic.

I may try a better OBDII reader, but I really don't think I'll find anything there unless it's any disruptions in airflow and/or fuel flow. If the computer is malfunctioning, it may not detect that anyway. I'm at a loss so far, but will keep debugging. I'd sure appreciate any thoughts.

 

[Adieu]

Did you disconnect the battery for any amount of time? Installing a new one or removing old one to plug into a wall charger counts, needing a jump but having enough juice to operate lights and locks doesn't.


If yes, throttle body dirty and adaptations reset by loss of power. Remove it off the truck and clean thoroughly on both sides.

 

[Hamfisted]

Are you the original owner ? Does it still have the original fuse box in it ? Check the PCM relay ( top right in the fuse box ...) for signs of melted plastic around the terminals.

 

[GoMach]

Thanks for the replies... I've been on an unexpected trip, but will get to this.

Adieu:
I've not recently disconnected the battery. Good call. I'll try that. Thanks. I'll disconnect then flip on the headlights to be sure no juice is there.

I'll check the throttle body too.

Hamfisted:
I am NOT the original owner (we've only had it for a year). Hmmm... good idea to check the PCM relay. I'll do that.

Will report these back (wife has vehicle right now).

 

[GoMach]

UPDATE (in hopes that someone knows things to try).

NOTE AGAIN: No codes are thrown.

HERE ARE THE THINGS I'VE TRIED:

• Cleaned MAF
• Replaced the air filter
• Replaced the DPFE and the two hoses to the EGR pipe from exhaust
• Disconnected the battery for an extended period (Thanks Adieu)
• Checked for any burn marks in the PCM relay (none. FWIW the starter never fails - Thanks Hamfisted)
• Cleaned Throttle Body (with throttle body cleaner - Thanks Adieu). I did not remove it yet... but did clean it as well as I could while mounted. Should I remove it?
• Replaced the fuel filter
• Replaced the fuel pump (what a pain - grumble that Ford offered no trap door)

The SHORT description of the problem is that after running nicely for an unspecified time, it will stumble and die over the course of a few seconds. Once in this state, it WILL die. I then turn it off, turn it back on (hear the fuel pump) and give it a go again. After doing this several times, it ALWAYS starts... and then runs beautifly again. Once going for a long time (maybe after 15 minutes) it will not do it again, and I can drive for hours.

OTHER TRENDS: It is like a switch is turned when it goes bad. Once it's "over it" it will start and it's like nothing ever happened. IT IS MORE COMMON for this to happen when going slowly like leaving a stop sign. But it has done it at speed too (but it's more rare). The most common thing recently is to do it 3 miles after running.

The ONLY reasonable idea I have is to try replacing the MAF. That's likely my next move. But... DAMN!

Could it be the fuel rail? But it happens so SUDDENLY with beautiful running before and after. It just doesn't seem like it could be a clog of any kind.

I fear a bad wire somewhere, which may be hard to trace.

Thanks so much for any help.

 

[Hamfisted]

More likely the fuel pump micro relay in the fuse box circuit board if it's still the original fuse box. There is a long history of this problem with the '03-'04 Expy's/Nav's/F-150's ....

Google Ford fuel pump relay problems and you will find hundreds of discussions and fixes.

If you're good at soldering, the G8QN replacement relay is heavier duty and will fix the issue for good. Otherwise buying a new fusebox will also fix the issue but the relays are the same as what burned up originally. But we haven't heard of replaced fuseboxes coming back with burned fuel pump relays.

 

[GoMach]

@Hamfisted .. Thanks! When you first commented on that, I only looked at the front of the fuse box and I saw no burning, etc. But I'm now going to take the fuse box out to look behind. Had I known how this thing was made, I would have done that the first time you mentioned it.

UPDATE: I got a better diagnostic tool and am learning about it (Autel MaxiLink ML629) and it reported the code P0231... this seems consistent with what @Hamfisted said. I did NOT change the MAF (it may not have anything to do with this).

NEXT UP: Check fuse box along with the R303 relay.

ALSO, I'll check the PCM relay R203 and fuses 32, 33 and 34 listed in a manual page I saw. But to me, it seems unlikely that the PCM related relay and fuses would do this fuel cutoff thing.

 

[RichardH]

I've been fighting a similar problem for a month on a 2003 EB 2wd.

After working with two worthless indy shops, I had a dealer replace the alternator harness/battery cables, starter cable, had the junction box replaced (at the indy tho), with a used.

In recent history I replaced the two hoses, EGR valve, and pressure sensor.

It turns out the DPFE I purchased off of Amazon was defective. I guess it was effecting the ST/LTFT and killing the engine. I though it was a different electrical issue. Dealer said it was EGR related. Once the Ford MFG part was installed at a ridiculous price, truck has been running perfect. Whatever, it's only money.

What codes are showing?

 

[Expy3]

Had the same problem for a month and fixed it by replacing the micro fuel pump relay. It is soldered on the cjb board, have to take out the cjb and you will see 5 micro relays and it is the center one. You will see one on YouTube on how to replace it by unsoldering to take it out.

 

[GoMach]

SEEMS RESOLVED: It was a bad relay for the fuel pump (R303). Found for $14 on ebay. Details below.

KEY TAKEAWAYS:

• An OBDII diagnostic tool that can see specific manufacturer PIDs is at times VERY VALUABLE (I saved the cost of a MAF... basically paying for the tool I bought, because the MAF was not the problem).
• Have a solder sucker for removing items from the circuit board.
• A P0231 (only read by the more advanced tool) could indicate fuel pump OR relay.
• The solution was a $14 relay found on ebay, by typing in the numbers off my old relay. (see the pic by @Expy3 above)

@Hamfisted - hit the problem right on the head on Nov 20 (above).

@RichardH - I also replaced the DPFE... did not fix it, but my old one had a broken post where the hose attached. I ALSO had trouble with a cheap DPFE and then bought a Motorcraft, which worked.

@Expy3 - Yep... that's the one I replaced. Great pics. Thanks.

BACKDROP: Truck ran well most of the time (some have had it die and not ever restart, but mine always restarted even if it took several attempts). But it would die when pulling out into traffic, making it dangerous.

TRIED WITHOUT PRIMARY SUCCESS: EGR hoses were needed, DPFE had bad connector for one hose, cleaned MAF (worked for 3 weeks so I thought this might be it). Cleaned throttle body (no effect). Had to replace starter in the middle of all this (independent problem). Traction control twice faked a problem (likely has corrosion, but it's low urgency - will look/clean later). Disconnected battery for a long time (no effect).

FUSE BOX: At first, I saw no burn marks (surface examination) so moved on. Replaced fuel pump (no effect - DAMN - costly, but still far less than the 1300 quoted).

RETURN TO FUSE BOX: Removed and examined closely after learning where R303 is (see @Expy3 photos above... that's R303 - the fuel pump relay). That relay is known to go bad. NOTE that everything at first looked fine when I removed it. But on close examination, there was slight (and I do mean slight) discoloration around R303... the center relay. That was enough to push me to replace it.

CODES... My only tool at the time was a BAFX OBDII tool & Torque Pro combo. This showed no codes. My thought at the time was a bad MAF sensor. Nope. I then bought an Autel ML629 and it read things that my old setup didn't... I got a P0231 - Fuel Pump Secondary Circuit Low. (The pro somewhat understandably said it was a bad fuel pump, but that was wrong.) The ML629 has profiles of many manufacturers and is clearly a more complete tool for special aspects (PID's - Parameter IDs)... it sees many manufacturer IDs that my older diagnostic setup could not. This turned out to be very valuable and PREVENTED me from buying a MAF - which was my planned next step. SEEING the message caused me to remember what @Hamfisted said and question the relay.

PROCESS FOR RELAY: Basically, unsolder the R303, and solder in a new one. SOME DETAILS (for anyone it may help): To see the area, you must remove the board like in @Expy3 's photo... and then track where the tabs go (NOTE CAREFULLY their orientation and take a picture) and then remove them, so you can remove the board from that back panel. Then you can get to the underside where the relay pins are soldered. Unsolder the R303. NOTE: Get a solder sucker. I'll admit that I used an air compressor to blow off the solder, but the big drawback is that the solder spreads out over the electronics. Mine was easy to clean off, but it made me uneasy (and small solder bits could remain). I'm getting a solder sucker next time. Once the old one was free (a bit of a pain), soldering in the new one was not hard. Careful not to melt on gobs of solder... it may spill over onto other circuits. Put it back together referencing pics to get it right (I used my pictures SEVERAL times even though I had expected that I would not need them. This has been working for over a week of very frequent use.

 

[RichardH]

SEEMS RESOLVED: It was a bad relay for the fuel pump (R303). Found for $14 on ebay. Details below.

KEY TAKEAWAYS:

• An OBDII diagnostic tool that can see specific manufacturer PIDs is at times VERY VALUABLE (I saved the cost of a MAF... basically paying for the tool I bought, because the MAF was not the problem).
• Have a solder sucker for removing items from the circuit board.
• A P0231 (only read by the more advanced tool) could indicate fuel pump OR relay.
• The solution was a $14 relay found on ebay, by typing in the numbers off my old relay. (see the pic by @Expy3 above)

@Hamfisted - hit the problem right on the head on Nov 20 (above).

@RichardH - I also replaced the DPFE... did not fix it, but my old one had a broken post where the hose attached. I ALSO had trouble with a cheap DPFE and then bought a Motorcraft, which worked.

@Expy3 - Yep... that's the one I replaced. Great pics. Thanks.

BACKDROP: Truck ran well most of the time (some have had it die and not ever restart, but mine always restarted even if it took several attempts). But it would die when pulling out into traffic, making it dangerous.

TRIED WITHOUT PRIMARY SUCCESS: EGR hoses were needed, DPFE had bad connector for one hose, cleaned MAF (worked for 3 weeks so I thought this might be it). Cleaned throttle body (no effect). Had to replace starter in the middle of all this (independent problem). Traction control twice faked a problem (likely has corrosion, but it's low urgency - will look/clean later). Disconnected battery for a long time (no effect).

FUSE BOX: At first, I saw no burn marks (surface examination) so moved on. Replaced fuel pump (no effect - DAMN - costly, but still far less than the 1300 quoted).

RETURN TO FUSE BOX: Removed and examined closely after learning where R303 is (see @Expy3 photos above... that's R303 - the fuel pump relay). That relay is known to go bad. NOTE that everything at first looked fine when I removed it. But on close examination, there was slight (and I do mean slight) discoloration around R303... the center relay. That was enough to push me to replace it.

CODES... My only tool at the time was a BAFX OBDII tool & Torque Pro combo. This showed no codes. My thought at the time was a bad MAF sensor. Nope. I then bought an Autel ML629 and it read things that my old setup didn't... I got a P0231 - Fuel Pump Secondary Circuit Low. (The pro somewhat understandably said it was a bad fuel pump, but that was wrong.) The ML629 has profiles of many manufacturers and is clearly a more complete tool for special aspects (PID's - Parameter IDs)... it sees many manufacturer IDs that my older diagnostic setup could not. This turned out to be very valuable and PREVENTED me from buying a MAF - which was my planned next step. SEEING the message caused me to remember what @Hamfisted said and question the relay.

PROCESS FOR RELAY: Basically, unsolder the R303, and solder in a new one. SOME DETAILS (for anyone it may help): To see the area, you must remove the board like in @Expy3 's photo... and then track where the tabs go (NOTE CAREFULLY their orientation and take a picture) and then remove them, so you can remove the board from that back panel. Then you can get to the underside where the relay pins are soldered. Unsolder the R303. NOTE: Get a solder sucker. I'll admit that I used an air compressor to blow off the solder, but the big drawback is that the solder spreads out over the electronics. Mine was easy to clean off, but it made me uneasy (and small solder bits could remain). I'm getting a solder sucker next time. Once the old one was free (a bit of a pain), soldering in the new one was not hard. Careful not to melt on gobs of solder... it may spill over onto other circuits. Put it back together referencing pics to get it right (I used my pictures SEVERAL times even though I had expected that I would not need them. This has been working for over a week of very frequent use.

Thank you so much for the write up.

I think I mentioned I did a junction box replacement, although used, so not the newer version. I believe the box is a two bolt and several plug operation, reasonably easy. I don't mind replacing for $350 (to $500) or so for OEM to gain reliability for years to come. I'll do the install.

I've replaced so many 'consumable' parts so to speak I'm comfortable with a 144K mile truck, with no new issues. Neutral safety, COP's, plugs, steering wheel switches (cruise/stereo), filters, EGR valve, 2 EGR hoses, pressure sensor, new battery, terminals (at dealer expense ugg), new alternator harness, cable to starter, along with a few other parts.

It's no spring chicken, and know things will come up.

I really appreciate the feedback I get from other users of these trucks.

Many thanks,
Dick

edit:

Of course I saved the old junction box - is it feasible to replace the R303 on the old box and improve the functionality/longevity?

 

[GoMach]

ADDITIONAL UPDATE: The truck is still doing well (fixed it on December 2, so 11 days of lots of use).

@RichardH - Glad it was helpful. Ah, makes sense. When I read your phrase "junction box" I just thought it was another box I didn't know about... should have realized that you were referring to the fuse & relay box.

CAN ONE IMPROVE THE OLD FUSE/RELAY BOARD? @RichardH - Since the problem is the relay itself, and not the board, I'd solder wires (for the relay's contacts) that lead outside the fuse/relay box and then to my own junction box. Then you could easily swap out either the same R303 if ever needed, OR you could find a better relay that uses the same electrical profile (what I'd call the coil connections and the final circuit switch leads).

REFLECTION (FWIW) ON THE NEW OEM BOARD VS. CHEAP SOLDER of R303 VS. CHEAP BOARD OFF EBAY: In retrospect, I can TOTALLY understand replacing it with an OEM to get the redesign. Given that my truck has lots of rust and 170k, I was lured (70%) by the $14 price of the relay and (30%) the "interesting factor" of the soldering job. THE RISK is what really would cause me to question the decision if I had no rust... because one could screw up the board. But I figured, if I screwed it up, I'd buy one then. Because of the price factor, I'd likely have gone with an ebay board KNOWING I'm not getting the better design. It would DEFINITELY Be a compromise to save bucks. But MY truck is has lots of rust (may have come from the north) and has 170K... so most decisions are geared toward making it last only another 80k or so. If I had a truck that had no rust, that might be enough alone to invest. If it had 100k (with prospects of another 150-200k) that'd likely seal it for spending to get the later design.

 

[RichardH]

ADDITIONAL UPDATE: The truck is still doing well (fixed it on December 2, so 11 days of lots of use).

@RichardH - Glad it was helpful. Ah, makes sense. When I read your phrase "junction box" I just thought it was another box I didn't know about... should have realized that you were referring to the fuse & relay box.

CAN ONE IMPROVE THE OLD FUSE/RELAY BOARD? @RichardH - Since the problem is the relay itself, and not the board, I'd solder wires (for the relay's contacts) that lead outside the fuse/relay box and then to my own junction box. Then you could easily swap out either the same R303 if needed. Additionally, you could find a better relay that uses the same electrical profile (what I'd call the coil connections and the final circuit switch leads).

REFLECTION (FWIW) ON THE NEW OEM BOARD VS. CHEAP SOLDER of R303 VS. CHEAP BOARD OFF EBAY: In retrospect, I can TOTALLY understand replacing it with an OEM to get the redesign. Given that my truck has lots of rust and 170k, I was lured (70%) by the $14 price of the relay and the 30% "interesting factor" of the soldering job. THE RISK is what really would cause me to question the decision if I had no rust... because one could screw up the board. But I figured, if I screwed it up, I'd buy one then. Because of the price factor, I'd likely have gone with an ebay board KNOWING I'm not getting the better design. It would DEFINITELY Be a compromise to save bucks. But MY truck is has lots of rust (may have come from the north) and has 170K... so most decisions are geared toward making it last only another 80k or so. If I had a truck that had no rust, that might be enough alone to invest. If it had 100k (with prospects of another 150-200k) that'd likely seal it for spending to get the later design.

Good points sir.

yep, no rust on my truck, great engine, don't mind spending another few hundred bucks if necessary. All new tires, good brakes and rotors, want to replace to ceramic pads soon.


Later replace that annoying rear popping from the AC stickied on this forum. Front AC works fine though.

 

[EliteFord]

Thanks for the write up. I'm about to pull out the fuse box tonight but still reading up.