Excursion stalls out
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Cross-Country
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Excursion stalls out
I have a 2003 Excursion. 6.0. studded. Intermittently it dies while driving but starts back up after minimal effort. Intermittently it runs rough with ICP in the 3000-3500 range. .FICM voltage 48.
When it dies on me the SCTx4 shows No Sync. It can be hundreds of mile between episodes. Truck is usually warm when it happens.
Anybody have any suggestions?
When it dies on me the SCTx4 shows No Sync. It can be hundreds of mile between episodes. Truck is usually warm when it happens.
Anybody have any suggestions?
Last edited by Chainfire; Dec 22, 2021 at 04:14 PM.
Fleet Owner
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Most of the time a stall will generate a cam sensor code or a crank sensor code. Interesting it didn't.
Quite a few things can cause intermittent stalling, so all effort to get clues is well worth it.
I guess you could start swapping parts if you have access to known good spares. Most shops do, and sometimes it is the best way to track down something intermittent.
Typical culprits:
ICP sensor
IPR valve
FICM (the FICM is more than a voltage converter, so 48V on the power side is only part of the function)
EBP sensor
Pretty much any v-reference sensor could also
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Cross-Country
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Yes it was at a friends shop. He has IDS.
I have quite a few Excursions and trucks I can rob parts off of if I have to.
I am leaning towards a faulty engine wiring harness as the culprit.
I was hoping for someone that may have had a similar problem to get some guidance.
Truck runs beautifully most of the time.
The thing that really puzzles me is the intermittent problem with no codes.
I am thinking it has to be a pcm wiring issue or cam or less likely crank sensor wiring issue for the pcm to lose sync.
The ICP surging to 3-4K is also weird.
I have quite a few Excursions and trucks I can rob parts off of if I have to.
I am leaning towards a faulty engine wiring harness as the culprit.
I was hoping for someone that may have had a similar problem to get some guidance.
Truck runs beautifully most of the time.
The thing that really puzzles me is the intermittent problem with no codes.
I am thinking it has to be a pcm wiring issue or cam or less likely crank sensor wiring issue for the pcm to lose sync.
The ICP surging to 3-4K is also weird.
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Cross-Country
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EBP sensor is a great idea.
That could cause the ICP surge.
It would not explain loss of sync intermittently.
That could cause the ICP surge.
It would not explain loss of sync intermittently.
Last edited by Chainfire; Dec 22, 2021 at 05:47 PM.
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Fleet Owner
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Many 6.0's have those symptoms, and the end fix can be quite diverse in them.
That said, surging at the higher rpm range will happen when an IPR valve gets flaky - but that is just a guess. Guessing gets expensive.
Certainly it can be a harness problem, but the engine harness is expensive. It could be an injector or injector harness, but that isn't exactly cheap.
No doubt that a cam or crank sensor issue could cause it also. Those sensors don't commonly fail, but a certain fraction of them do.
Sometimes the FICM plugs aren't fully seated and can cause the stalling - free to check anyway.
Also, the engine will run fine with the ICP and EBP sensors unplugged. You might as well try that and inspect the wiring to them at the same time.
Edit - since you mentioned the "No Sync" observation, then the FICM can cause a loss of Sync when it gets flaky. Possibly an issue with v-reference voltage could cause a loss of Sync. Anyway - you might post which Sync it is that is not being registered, since there are two Syncs. That said, when it dies, it will always show no Sync (need cranking or engine rotation to have Sync). Since it "re-starts with minimal effort", you obviously have Sync on the re-start.
If you live in a location where rust is an issue, the cam sensor can get "rust jacked" and cause intermittent stalls.
So many possibilities. Of course there is always the approach to just change out the cam and crank sensors and see how it does.
That said, surging at the higher rpm range will happen when an IPR valve gets flaky - but that is just a guess. Guessing gets expensive.
Certainly it can be a harness problem, but the engine harness is expensive. It could be an injector or injector harness, but that isn't exactly cheap.
No doubt that a cam or crank sensor issue could cause it also. Those sensors don't commonly fail, but a certain fraction of them do.
Sometimes the FICM plugs aren't fully seated and can cause the stalling - free to check anyway.
Also, the engine will run fine with the ICP and EBP sensors unplugged. You might as well try that and inspect the wiring to them at the same time.
Edit - since you mentioned the "No Sync" observation, then the FICM can cause a loss of Sync when it gets flaky. Possibly an issue with v-reference voltage could cause a loss of Sync. Anyway - you might post which Sync it is that is not being registered, since there are two Syncs. That said, when it dies, it will always show no Sync (need cranking or engine rotation to have Sync). Since it "re-starts with minimal effort", you obviously have Sync on the re-start.
If you live in a location where rust is an issue, the cam sensor can get "rust jacked" and cause intermittent stalls.
So many possibilities. Of course there is always the approach to just change out the cam and crank sensors and see how it does.
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Cross-Country
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The icp increased to 3-4K but the rpm stayed in the 2k range.
I have every part for these motors many times over including wiring harnesses but it’s a pain to change all that stuff without some sort of direction.
I have every part for these motors many times over including wiring harnesses but it’s a pain to change all that stuff without some sort of direction.
Many 6.0's have those symptoms, and the end fix can be quite diverse in them.
That said, surging at the higher rpm range will happen when an IPR valve gets flaky - but that is just a guess. Guessing gets expensive.
Certainly it can be a harness problem, but the engine harness is expensive. It could be an injector or injector harness, but that isn't exactly cheap.
No doubt that a cam or crank sensor issue could cause it also. Those sensors don't commonly fail, but a certain fraction of them do.
Sometimes the FICM plugs aren't fully seated and can cause the stalling - free to check anyway.
Also, the engine will run fine with the ICP and EBP sensors unplugged. You might as well try that and inspect the wiring to them at the same time.
Edit - since you mentioned the "No Sync" observation, then the FICM can cause a loss of Sync when it gets flaky. Possibly an issue with v-reference voltage could cause a loss of Sync. Anyway - you might post which Sync it is that is not being registered, since there are two Syncs. That said, when it dies, it will always show no Sync (need cranking or engine rotation to have Sync). Since it "re-starts with minimal effort", you obviously have Sync on the re-start.
If you live in a location where rust is an issue, the cam sensor can get "rust jacked" and cause intermittent stalls.
So many possibilities. Of course there is always the approach to just change out the cam and crank sensors and see how it does.
That said, surging at the higher rpm range will happen when an IPR valve gets flaky - but that is just a guess. Guessing gets expensive.
Certainly it can be a harness problem, but the engine harness is expensive. It could be an injector or injector harness, but that isn't exactly cheap.
No doubt that a cam or crank sensor issue could cause it also. Those sensors don't commonly fail, but a certain fraction of them do.
Sometimes the FICM plugs aren't fully seated and can cause the stalling - free to check anyway.
Also, the engine will run fine with the ICP and EBP sensors unplugged. You might as well try that and inspect the wiring to them at the same time.
Edit - since you mentioned the "No Sync" observation, then the FICM can cause a loss of Sync when it gets flaky. Possibly an issue with v-reference voltage could cause a loss of Sync. Anyway - you might post which Sync it is that is not being registered, since there are two Syncs. That said, when it dies, it will always show no Sync (need cranking or engine rotation to have Sync). Since it "re-starts with minimal effort", you obviously have Sync on the re-start.
If you live in a location where rust is an issue, the cam sensor can get "rust jacked" and cause intermittent stalls.
So many possibilities. Of course there is always the approach to just change out the cam and crank sensors and see how it does.
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So - which Sync were you having an issue with?
I have difficulty seeing you get to 4000 ICP at 2000 rpm unless maybe there is a restriction in the high pressure system, or the IPR valve is sticking. 4045 ICP is the max. You don't normally get that high except when accelerating hard.
I would verify that value with ICP sensor volts. I would also try running with the ICP disconnected, since that is the value that is surging. It is a free test.
I would still inspect the FICM plugs and the ICP and IPR connectors and wiring.
I have difficulty seeing you get to 4000 ICP at 2000 rpm unless maybe there is a restriction in the high pressure system, or the IPR valve is sticking. 4045 ICP is the max. You don't normally get that high except when accelerating hard.
I would verify that value with ICP sensor volts. I would also try running with the ICP disconnected, since that is the value that is surging. It is a free test.
I would still inspect the FICM plugs and the ICP and IPR connectors and wiring.
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Cross-Country
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I’m not with truck at moment.
As far as which sync the truck runs great when I have diagnostic tools with me. the Sct is what’s normally on board it says no sync but I don’t know which sync.
It can do a whole 500 mile run from WA to southern Oregon and not have a problem then it stalls out a couple times in a day.
As far as which sync the truck runs great when I have diagnostic tools with me. the Sct is what’s normally on board it says no sync but I don’t know which sync.
It can do a whole 500 mile run from WA to southern Oregon and not have a problem then it stalls out a couple times in a day.
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I believe that the most likely situation is that your SCT does not have a fast enough "data sample rate" and the loss of Sync that you see (either FICM Sync or Cam/Crank Sync) is a result of the stall, instead of the cause of it. Because of that, I believe that the advice above is still applicable.
If you firmly believe that the loss of Sync is the initiator, then my guess at the most likely causes would come down to the crank sensor or its wiring, the cam sensor or its wiring, or the FICM or its wiring. It could be in other parts of the harness, or other sensors, or even the PCM I suppose, but I just think that that is a very low probability.
If it were the crank sensor, you might see some rpm speed fluctuations. Whenever you lose Sync, I believe that the IPR will default to 14%. Remember though, the IPR % duty cycle is a command, not an actual valve position.
An interesting view of the control system as it relates to the power monitor:
If you firmly believe that the loss of Sync is the initiator, then my guess at the most likely causes would come down to the crank sensor or its wiring, the cam sensor or its wiring, or the FICM or its wiring. It could be in other parts of the harness, or other sensors, or even the PCM I suppose, but I just think that that is a very low probability.
If it were the crank sensor, you might see some rpm speed fluctuations. Whenever you lose Sync, I believe that the IPR will default to 14%. Remember though, the IPR % duty cycle is a command, not an actual valve position.
An interesting view of the control system as it relates to the power monitor:
Power Monitor- Power Monitor is used to insure that the modules in the system do not start
fueling and create power greater than demand. In the Power Monitor System one module serves
as a watchdog for another module. The FICM sends out a signal which is monitored by the TCM
(which is packaged in the PCM). If something wrong is detected, the two CMPO and CKPO
outputs going to the FICM can be turned off by the PCM/TCM thus disabling fueling of the FICM.
If it were my truck, I would have ForSCan with me on the next trip.
fueling and create power greater than demand. In the Power Monitor System one module serves
as a watchdog for another module. The FICM sends out a signal which is monitored by the TCM
(which is packaged in the PCM). If something wrong is detected, the two CMPO and CKPO
outputs going to the FICM can be turned off by the PCM/TCM thus disabling fueling of the FICM.
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Cross-Country
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Great info and advice. Very much appreciated.
I am debating about throwing some parts at it.
Probably cam sensor, IPR, Ficm. Then I’ll run it.
I also have the intermittent no cluster gauges, so I’ll put another cluster in it while I’m at it and a leaky hydro boost needs replaced.
I guess I’ll get Forscan as well.
im not home till the first of the year but I’ll keep u updated.
thank you
I am debating about throwing some parts at it.
Probably cam sensor, IPR, Ficm. Then I’ll run it.
I also have the intermittent no cluster gauges, so I’ll put another cluster in it while I’m at it and a leaky hydro boost needs replaced.
I guess I’ll get Forscan as well.
im not home till the first of the year but I’ll keep u updated.
thank you
Fleet Owner
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Posts: 27,881
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Some codes clear after a few drive cycles, so if you scan after those drive cycles, you will lose that information. Scanning immediately after the event might yield some additional information.
The updates are greatly appreciated!! Your solution, when you nail it, could help a number of others!!
Good luck and Merry Christmas.
The updates are greatly appreciated!! Your solution, when you nail it, could help a number of others!!
Good luck and Merry Christmas.