Idle issues.

[Ozymandias]

I've no idea why your LP pressure fluctuates so much just idling, that is indeed weird.

 

[Lordsman]

With so many illegitimate parts available I hope you bought your FCA from a reputable place that sells good parts. I made that mistake with an FCA I bought online. When I installed it nothing changed, all bucking, jerking, hesitation, especially when engine was cold continued. Took it to the dealer, told them my issues and they found nothing wrong. Everything told me from what I read on this site and advice from this site, told me it was bad. Bought another one, this time from Geno's and the truck has been fine since. My .02.
Hope you get it figured out.

 

[Eric_Cumminsguy6.7]

So, after unplugging the FCA while it was running I see some odd things. Before Unplugging it commanded and actual were pretty close at 5k psi. The actual was still fluctuating a bit. I unplugged the FCA and the pressure spiked to 18K for a second and then dropped to ~12k and held there. Commanded did some weird things, maybe it saw the pressure spike and wasn't happy with that and trying to get it down I am not sure on that part. But what was weird was when it was plugged back in both commanded and actual hung around 8500 PSI. Turning the truck off and they were at 5kPSI and then unplugged and plugged back in it did the same thing. I should add there has been no recent work or updates done to the truck to cause this. My question is, is the lift pump going out or not flowing enough fuel to get to the high pressure (spike of 18kPSI) and stay there. And why after plugging it back in will it stay at 8500PSI commanded until the truck is shut off?

I don't think it will harm anything, it just sounds horrible like a 2nd Gen 24V all the time. Pressure isn't out of spec for the Motor, just for the load.
If this would harm it I'm very sure they would have programmed it that way to shut down in this case (high rail pressure for given rpm).

 

[Eric_Cumminsguy6.7]

With so many illegitimate parts available I hope you bought your FCA from a reputable place that sells good parts. I made that mistake with an FCA I bought online. When I installed it nothing changed, all bucking, jerking, hesitation, especially when engine was cold continued. Took it to the dealer, told them my issues and they found nothing wrong. Everything told me from what I read on this site and advice from this site, told me it was bad. Bought another one, this time from Geno's and the truck has been fine since. My .02.
Hope you get it figured out.

No, Still having issues. My local place is zimmeys. They had a genuine bosch replacement new sitting on the shelf for $152. They haven't sold me a bad part yet, not saying that this couldn't still be bad. It could be possible. I think geno's was $142 or close with a 4 day shipping time I figured I'd try the immediate option so I'd know if it'd fix it or if my issue was elsewhere.

 

[AH64ID]

Your rail pressure should have spiked to 26K psi and opened the HPRV. I wonder if you have a weak HPRV.

 

[Eric_Cumminsguy6.7]

Your rail pressure should have spiked to 26K psi and opened the HPRV. I wonder if you have a weak HPRV.

I can kinda see that, maybe? Why though would I see fluctuations at 5k, and not at 12k then? Even not getting up to the 26k it still held steady at 12k with no issues or deviations makes me wonder if it's getting enough fuel to make pressure. If it has enough to make 20k and sucks that out and only has enough fuel to make 12k isn't that what it'd make? From what I can see the pop off for those is 32kPSI? Does that sound about right

 

[Ozymandias]

Yeah, you should see 22-23k at least at this test.

 

[Eric_Cumminsguy6.7]

Yeah, you should see 22-23k at least at this test.

Is that 22-23k stable pressure? About stable I mean I'm not exactly worrying about splitting hairs here, just as long as it's not fluctuating like in previous graphs have shown causing the rough idle and driving issues.

 

[Ozymandias]

Whats the Max rail pressure you see while driving with the Scanner connected and the FCA plugged in of course.
Usually the highest numbers up to 23k I see is at around 1500-1800rpm with a steady throttle and medium load.
WOT and high rpms give lower numbers like 12k to 15k.

Please report back with that.

 

[Ozymandias]

Is that 22-23k stable pressure? About stable I mean I'm not exactly worrying about splitting hairs here, just as long as it's not fluctuating like in previous graphs have shown causing the rough idle and driving issues.

Yeah more or less stable as the oberflow valve regulates the rail pressure then, the CP3 is a max volume equals max pressure.

 

[Ozymandias]

Rail pressure is made by the CP3 of the amount of fuel that the FCA allows into the high pressure pump. The less it gives into the pump the lower the pressure is inside the rail as the injectors drain the rail continously.

 

[Eric_Cumminsguy6.7]

Whats the Max rail pressure you see while driving with the Scanner connected and the FCA plugged in of course.
Usually the highest numbers up to 23k I see is at around 1500-1800rpm with a steady throttle and medium load.
WOT and high rpms give lower numbers like 12k to 15k.

Please report back with that.

I wish there was a way I could link these files so you guys can mess around with them and see whatever you wanna see. Unfortunatley i can t figure out how to export them off of the scan tool. It looks like driving and shifting to 4th(I don't use 1st gear) I see Sub 19K @1800RPM

 

[Eric_Cumminsguy6.7]

Then it looks like at speed I usually cruise around in 5th or 6th. @1400RPM it's just under 7500PSI

 

[Ozymandias]

That looks way to low for the given circumstances, 7k I see at idle, never while driving.
I have a gauge in mine for rail pressure so I see all the time what's going on.

 

[Eric_Cumminsguy6.7]

That looks way to low for the given circumstances, 7k I see at idle, never while driving.
I have a gauge in mine for rail pressure so I see all the time what's going on.

I'm not sure if it has anything to do with it or not. I got a letter in the mail about the emissions reprogram for the recall. Well slight issue there is that I'm deleted so there is no emissions for them to even program or mess with. There is no like over the air updating for these trucks or anything like that so they can make it "mess up" so I have to take it to them for it to be fixed?
I don't even see that at idle, it's always calling for 5k. Except for today when I plugged that FCA back in and then it started calling for 8500, which is still weird to me that even blipping and a rev hold and it wouldn't command any less than 8500PSI. I'd have to key cycle it and when it started again it was commanding 5k

 

[Ozymandias]

Probably, you need to have that examined from a Pro in these engines.
All I can say is that your Rail pressure ist way to low with the FCA disconnected.
As said, disconnected it gives maximum flow to the CP3, all that goes and the CP3 then maxes out its pressure as high as it mechanically can without any electronic interference*, no matter what. You have to have a diesel tech to follow up on this route and find the root cause for this low pressure.

*the FCA is the single only part with which the ECM controls rail pressure.

 

[Eric_Cumminsguy6.7]

Probably, you need to have that examined from a Pro in these engines.
All I can say is that your Rail pressure ist way to low with the FCA disconnected.
As said, disconnected it gives maximum flow to the CP3, all that goes and the CP3 then maxes out its pressure as high as it mechanically can without any electronic interference*, no matter what. You have to have a diesel tech to follow up on this route and find the root cause for this low pressure.

*the FCA is the single only part with which the ECM controls rail pressure.

Just out of curiosity, at what voltage do issues start cropping up? I'll need to meter the batteries to verify but I pulled the graph for the Control Module Voltage and the commanded pressure kinda mimicked it? *EDIT* I might have put my foot in my mouth on this one, I've gone through all my other charts and found that the CMV didn't do this before. After a bit it did even out at 14.5v I will still check the batteries when I can again to make sure one or both aren't low as the truck was sitting for twoish days before I unplugged the FCA.

 

[Ozymandias]

11.9 at the ECM sure is low and can have an influence, but doesn't explain your low pressure disconnected.

 

[Eric_Cumminsguy6.7]

https://youtube.com/shorts/UNAJa25NqOE

Link to video of a walk around while the truck is running. ABS and TC lights are from me. This issue has been going on prior to me doing work on the hub assembly and pulling the front driveshaft. It might be a little hard to hear in the beginning, but easier to hear near the end when I walk back to the exhaust again.

 

[AH64ID]

HPRV should be right around 26K.

7.5K at cruise seems too low. Is that what your actual pressure shows? Or your demanded pressure?