B6.7 CM2350

[kunzme]

I've got a B6.7 in a KW t270 (I know it's small for this group). The truck came to me with a failed DOC and DPF and a 2692 code logged. I had them recored and had the SCR checked. Replaced differential pressure sensor. Set DPF assy to 0. Flashed ECM to the most current file. Test drove 5 miles and got a 2693 code. Engine did a regen but runs rough when regenning, soot load came down to .47 from 2.68. Checked for exhaust leaks. Cut out injectors and they all pulled the same and passed performance test. Cleaned egr valve and sensor ports. Cleaned intake. Removed 6 injectors (even though we couldn't fault them) had them bench checked. Replaced crankcase filter. Will not pass the restriction test for the dpf system, but passes every other test. After doing the restriction test the ash load will go to 100.8. If I drive it with it thinking the ash load is high the soot load climbs at a normal rate and fluctuates up down, today I drove it 60 miles and the highest the soot level got to was 1.2. Eventually it would require a regen like normal. If I set the ash back to zero the truck won't make it 5 miles before it says the soot is severe level. Has anyone heard of this?

[Rawze]

The 'soot' and 'ash' counters do not count down in the ecm, and they ignore the fact that the elements may show lower numbers. ... they only count up and special procedure needs to be performed to reset them.

The correct way is to to physically pull off the DOC and DPF and have them baked, de-ashed, and flow tested. Then after re-installing them, perform a DPF replacement procedure in Insite to reset all the soot counters in the ecm.

[kunzme]

(05-02-2023 )Rawze Wrote:  The 'soot' and 'ash' counters do not count down in the ecm, and they ignore the fact that the elements may show lower numbers. ... they only count up and special procedure needs to be performed to reset them.

The correct way is to to physically pull off the DOC and DPF and have them baked, de-ashed, and flow tested. Then after re-installing them, perform a DPF replacement procedure in Insite to reset all the soot counters in the ecm.

That is what I did, even had them flow tested again after being re-cored. We then used insite to perform the dpf replacement procedure. But as long as it shows the ash at 0% it will build soot level so fast it wants to regen every few miles. I am thinking this is what led to the dpf failing in the first place.

[windowrattler]

Are you getting actual soot or is there maybe an issue with the dpf differential sensor being clogged or bad?

Edit: second read through I see it's been changed. I lack reading comprehension.

[Rawze]

also, what does the regen history look like.. and has anyone cleaned out the egr cooler .. did a thorough EGR tune-up on the engine, etc... + checked for CAC leaks, exhaust leaks, turbo inspection, etc.. because it is the engine that makes the soot.. not the DPF.

[kunzme]

Replaced EGR cooler during this repair, cleaned egr valve, differential pressure ports and intake. There is a very small amount of oil in cac plumbing. No boost or exhaust leaks, we have checked for each multiple times. Truck rans clean with downpipe unhooked from dpf. I don't believe it is actually building soot. I think there is something with the programming. It doesn't make any sense why if it shows 100% ash load it will perform fine. As soon as you reset with insite and the ash load goes to 0% it thinks it is building soot and tries to regen every few miles.

[Rawze]

(05-03-2023 )kunzme Wrote:  ... I think there is something with the programming.
...

Then make sure it has the latest program from the engine maker in it and that the program in the ecm matches the engine ser# exactly.

What exactly are the list of faults you are getting and how often?.

When is the last time someone cleaned or replaced the Doser injector?.

What does the regen history look like?.. maybe a screen shot of it?.

and by the way... fault code 2692 comes back as intermittent wiring to one of the DPF components. When is the last time someone pulled apart the main harness and checked the pins in the connectors?... and traced the wiring back to the components and ensured it was not partially rubbed thru somewhere along the frame or something?.

[kunzme]

Program matches the S/N and is the latest calibration
We get 1921 then 1922 if we reset the ash load to 0
Doser injector has been replaced this repair
I will get a screen shot of regen history
We have checked wiring by inspecting and load testing circuits, checked pins in connectors for tension. [/color]

[Rawze]

(05-03-2023 )kunzme Wrote:  Program matches the S/N and is the latest calibration
We get 1921 then 1922 if we reset the ash load to 0
Doser injector has been replaced this repair
I will get a screen shot of regen history
We have checked wiring by inspecting and load testing circuits, checked pins in connectors for tension. [/color]

1921 = DPF Delta-P sensor back- pressure reading itself is too high.

1922 = DPF sensor is unplugged or shorted to +5volts power.

That means that something is still actually physically wrong with the DPF Delta-p sensor, its wiring, or its feed-tubes. It will not throw those faults unless the ecm is seeing bad or shorted out voltages from the sensor itself.

Is the sensor brand new?.. and where did you get it for?... Official OEM Cummins?.. or ordered online?, or got it from some non-OEM supplier?. - could be a chineesuim fake sensor for all anyone knows. Fake, or sub-par quality sensors are a plague in trucking right now.

Might want to unplug all the harnesses and connectors to the cans, etc.. amnd look for corrosion or signs of contamination somewhere.. double check the wiring to se if it has not gotten compromized somewhere along the way.


Come to think if it.. on some of those smaller trucks, or older trucks, the feed tubes from the DPF unit were notorious for getting sooted up internally and causing bad readings to the DPF Delta-P sensor. Cracked bushings, or other problems with the feed tubes would make it read high as well.