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Still fighting the drop in rail pressure at high commanded rail pressure. Getting progressively worse, so I really need to get my return rates checked, and get either the injectors or injection pump replaced, fingers crossed that it’s the injection pump, since it’s only around 500 bucks. If it’s injectors, I might have to hit that fella up again down in Columbus.


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What's your mileage at these days?
 

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Setting the truck on fire tonight at midnight. Who wants it?


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Setting the truck on fire tonight at midnight. Who wants it?


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What happened during the 14 days between posts?
 

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Double subd for an explanation
 

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Truck let me sit down in West Virginia yesterday afternoon. Been having some weird issues the last two weeks that would randomly throw the truck into limp mode.

Happened a few times that when I would start the truck up in the morning, the turbo vanes would go to 100%, and it would limp. I thought it was either vanes sticking, or then the electronica actuator on the turbo. I could usually turn the truck off and let the ECM reset, start it back up and it was fine. I think I was missing the fact that my fuel rail pressure was maxing out, and that in turn caused the vanes to go to 100%.

Ended up going into limp mode yesterday, and nothing I did made a difference anymore. Started digging through stuff on my scanner, and realized I wasn’t getting a fuel rail pressure reading at all, just read 0. That’s what was making the truck limp.

Fingers crossed that I can throw a new sensor at it and the issue goes away, along with the turbo actuator issue. Maybe, just maybe that’s tied in to my low rail pressure reading while I’m towing. Kind of doubt it, but it never hurt anybody do you have a little hope.

Should pick up a sensor this afternoon and install it, fingers crossed.


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Dont burn it yet it's been a pretty good truck I would say with all the towing and miles you have put on it
 

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Ok fella’s, I see there hasn’t been any post to this one in several days but I’m hoping some of you are still willing to dish out some helpful advise. From the technical info I’ve seen posted, I know someone here knows the answer to my issue. Been in the commercial transport game for many years and have had multiple units dating all the way back to the LLY, so I’ve seen many of the different scenarios being discussed here. By the way Matt, the amount of useful information here on the L5P is priceless. Stumbled across this thread when I went searching because I’ve got one that currently has me stumped. Hopefully your coming out ok on yours but the lack of a post is cause for concern.

So this unit keeps eating the injector connector for #4. Get P0204 code - injector #4 open control circuit, then goes into limp. We have replaced the connector itself (Several times), replaced the connector and the injector together all with the same result. It will run for another 5K miles or so without a hiccup and then it will start to stumble here or there (like a couple times in a 600 mile day). Then in the next day or two, it will code out and the process repeats. The tech’s have showed me the failed connectors and they usually have at least 1 terminal that is all blackened .... not melted .... just looks like what repeated arcing might cause. They say the harness checks out fine when they get the fix completed which matches how it acts because it will run for another 5K or so but its like the process of operation is causing the degeneration.

Let the answers start flowing because I’m tired of messing around with this thing. It needs to turn in a full month of consistent dependability or it’s gonna have to go.
Fingers Crossed!!
 

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I need to update the thread. Got a few issues resolved, and a few ongoing.


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Ok fella’s, I see there hasn’t been any post to this one in several days but I’m hoping some of you are still willing to dish out some helpful advise. From the technical info I’ve seen posted, I know someone here knows the answer to my issue. Been in the commercial transport game for many years and have had multiple units dating all the way back to the LLY, so I’ve seen many of the different scenarios being discussed here. By the way Matt, the amount of useful information here on the L5P is priceless. Stumbled across this thread when I went searching because I’ve got one that currently has me stumped. Hopefully your coming out ok on yours but the lack of a post is cause for concern.

So this unit keeps eating the injector connector for #4. Get P0204 code - injector #4 open control circuit, then goes into limp. We have replaced the connector itself (Several times), replaced the connector and the injector together all with the same result. It will run for another 5K miles or so without a hiccup and then it will start to stumble here or there (like a couple times in a 600 mile day). Then in the next day or two, it will code out and the process repeats. The tech’s have showed me the failed connectors and they usually have at least 1 terminal that is all blackened .... not melted .... just looks like what repeated arcing might cause. They say the harness checks out fine when they get the fix completed which matches how it acts because it will run for another 5K or so but its like the process of operation is causing the degeneration.

Let the answers start flowing because I’m tired of messing around with this thing. It needs to turn in a full month of consistent dependability or it’s gonna have to go.
Fingers Crossed!!
We used LBZ connectors when we fixed mine, no issue since. You can get what’s called a gold plated connector, I think it’s just the color of the pins. Supposed to make a better connection.


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We used LBZ connectors when we fixed mine, no issue since. You can get what’s called a gold plated connector, I think it’s just the color of the pins. Supposed to make a better connection.


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Gold plated electrical connectors are quite common. Gold is an excellent conductor and it does not tarnish or corrode so the connection is never degraded that way. The gold plating is VERY thin.
 
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Thanks for the info on my injector issue guys.
Are the stock LBZ connectors gold plated or is that a special order from somewhere ... and if special order, do you recall where you can pick them up?
It’s just odd to me that I’m having all this trouble with #4 but not one bit of issue out of any of the others. Matt .... sorry if it’s posted in this thread somewhere (I haven’t had the time to read through all of it yet) but when you had trouble ... was it confined to just one injector or was it trouble with multiple?
Does anyone know, is the signal voltage being supplied to the injectors coming straight from the ECM ... or where is the source? Thought has crossed my mind ... wonder if the voltage on #4 circuit could be off a bit at the source and in turn causing the break-down in the connector over time??
This is a 2017 btw. 180K on it and nearly 100% of that is heavy towing (26K to 38K gross combination).
No other DTC’s or issues besides just this injector issue.
 

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Thanks for the info on my injector issue guys.
Are the stock LBZ connectors gold plated or is that a special order from somewhere ... and if special order, do you recall where you can pick them up?
It’s just odd to me that I’m having all this trouble with #4 but not one bit of issue out of any of the others. Matt .... sorry if it’s posted in this thread somewhere (I haven’t had the time to read through all of it yet) but when you had trouble ... was it confined to just one injector or was it trouble with multiple?
Does anyone know, is the signal voltage being supplied to the injectors coming straight from the ECM ... or where is the source? Thought has crossed my mind ... wonder if the voltage on #4 circuit could be off a bit at the source and in turn causing the break-down in the connector over time??
This is a 2017 btw. 180K on it and nearly 100% of that is heavy towing (26K to 38K gross combination).
No other DTC’s or issues besides just this injector issue.
I had issues with four different injectors, at three different times. Injector number four was involved every time though, it was replaced three times before I decided to replace the pigtails.

Can’t help you with where the voltage is supplied from, I’d have to look at a schematic.

Honestly not sure on the gold plated connectors either, I got them through my local diesel shop.


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A few updates on the truck. Thanks to Kevin and Joe for help with a little diagnosing and part numbers.

Put a new fuel rail pressure sensor on the front of the passenger side rail. 100% fixed the issue of not seeing any pressure at all and going into reduced power mode. Been fine for a few thousand miles now.

Had a transfer case failure a few weeks ago. Something broke the high/low shift fork, and the gear in the shift fork kept wanting to slip out. Took it out, and got a local guy to look it over on the inside. He said just replace the shift fork and roll on so that’s what I did. Failed again within a Thousand miles, so there’s another issue in there somewhere. Second time it failed I was in North Carolina close to my brothers place, so went to his place overnight and lucked out on finding a used one locally there. Local Mechanic worked me in the next morning, and I was back on the road. Want to pull the old transfer case apart and go through it and try to find out what’s going on so I can’t repair it.

New injection pump should be here tomorrow, hopefully I can get it replaced over the weekend or first of next week. Rail pressure drop has progressively gotten worse, and it’s pretty miserable to try to drive/tow with it right now.

Started getting a code last week for the turbo vane position actuator reading out of spec. Diagnosing is pointing to a faulty actuator, but could very possibly be something in the turbo as well. I can pick up a used low mileage turbo at the local Duramax shop for 400 bucks. Plan on swapping out the actuator first since it’s only four bolts right on top of the turbo, very accessible. If that doesn’t work I’ll put in the used turbo, I’m thinking either one of those should fix the issue.


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almost willing to bet there's a bearing starting to fail in your transfer case. don't know a damn thing about transfer cases but with all those miles and guessing on a basic level what's in there, I'd put decent money on a bearing.
 
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