CM871 High DOC temp during regen

[tariqzai]

Hi everyone, I have regen issue with my 2009 Volvo with CM871. During Regen instead of DOC temp staying steady and DFP temps going up, this engine shows DPF outlet temp staying steady while DPF intake and DOC temps keep going up (1000+). I have this truck for 3 years and every forced regen i did was successful and most of the time DPF differential pressure would be zero after the regen. Problem started few days back when DPF intake and outlet temp will not go higher than 600 and dosser injector was staying off all the time, I replaced the dosser injector and now dosser injector opens but instead of heat going through the DPF intake and outlet, data shows high temp on catalyst and DPF intake, while DPF temp stays around 550-600. Looking at the temps data during regen it appears like DOC and DPF outlet sensor connections are swapped, I checked these sensors physically on both filters and these wires are too short to be hooked up to the wrong connector. I will really appreciate if anyone can help me with this. (I have pulled the DOC and DPF filters and both appear clean)
Thanks
Tariq

[Rawze]

Take DOC and DPF to stealeras$it that has proper machine. Have Baked the DOC and DPF, de-ashed, and flow tested.

How old are DOC and DPF?. How many miles?

-- According to the pic of the temps, te DOC inlet is too high, and it loks exactly like when someone swaps around the DPF inlet and outlet temp sensors. - DOC and DPf sensors are not easily swapped,... but DPF inlet/outlet sensors/plugs can be improperly swapped, as the cables are actually long enough for this to happen.

May be that your egr valve is getting stuck? causing too high DOC inlet temps? or some other egr issue?

Could also be fuel burning against DOC instead of DPF because of exhaust leaks or some other problem...maybe fuel not spraying properly?.

just some things to think about any ways.

BTW: How were those elements cleaned? -- Hopefully not with some kind of liquids or some other half-arssed method... Cleaning those DOC and DPF elements improperly is the death of them/ruins them fairly quickly. Could be that they have simply gone bad.

[tariqzai]

(04-12-2020 )Rawze Wrote:  Take DOC and DPF to stealeras$it that has proper machine. Have Baked the DOC and DPF, de-ashed, and flow tested.

How old are DOC and DPF?. How many miles?

-- According to the pic of the temps, te DOC inlet is too high, and it loks exactly like when someone swaps around the DPF inlet and outlet temp sensors. - DOC and DPf sensors are not easily swapped,... but DPF inlet/outlet sensors/plugs can be improperly swapped, as the cables are actually long enough for this to happen.

May be that your egr valve is getting stuck? causing too high DOC inlet temps? or some other egr issue?

Could also be fuel burning against DOC instead of DPF because of exhaust leaks or some other problem...maybe fuel not spraying properly?.

just some things to think about any ways.

BTW: How were those elements cleaned? -- Hopefully not with some kind of liquids or some other half-arssed method... Cleaning those DOC and DPF elements improperly is the death of them/ruins them fairly quickly. Could be that they have simply gone bad.

Thanks for the reply, truck has 550k miles, these filters have not been cleaned in last 300k miles. Can't tell if the previous owner had cleaned them. I am taking it to stealeras$it, will do EGR tune up as well, will update after couple days.

[bwake]

I have attached several images that may help out here.
It looks like you may have an ash plugged DPF which needs to be properly baked and cleaned out. Once cleaned, they will perform a flow test to ensure that it's cleaned and flowing as it should.

[tariqzai]

Thanks Bwake, Filters will be done cleaning this after noon and I will run the regen to see if it fixed the issue, will update tonight.

[tariqzai]

got both filters cleaned and put back, still same thing, DOC temp too high and outlet in 500ish. I saw some soot around egr cooler flexible pipe and exhaust manifold, took egr cooler out and it looked fine, working on replacing manifold gaskets now, will do EGR tune up following Rawze's procedure.

[JimT]

You mentioned that the doser injector was recently replaced. You may want to remove it from the exhaust elbow and double check that the gasket was put on correctly. I remember a pic Rawze shared of someone's doser where the gasket was misaligned and blocking most of the fuel spray. There is also a "thermal isolator" that shrinks over time. If it wasn't replaced with a new one when they did the doser then it could be affecting the performance. Likewise if the assembly wasn't properly torqued down there could be a bad seal letting air into the system. If there is an exhaust leak somewhere before the DOC then the fuel could be igniting prematurely. Just another reason to double check that doser.

Of course, you might want to double double check that the readings are coming from the correct location. If you have a thermal imaging camera then you can verify not only the correct locations getting hot, but also the approximate temp readings. Double check the wires and make sure everything is plugged in to the right locations. On my system the plugs only mated to the matching connector, but the temp sensor could have been screwed in to the wrong hole. --- I know you said you checked this already, but sometimes silly mistakes like this can be the easiest to miss.

Finally, the pictures above show what looks like orange coolant spots getting on to the DOC and partial clogging of the DPF (hence the off center soot buildup). DPF could have been a result of ash buildup so a cleaning might have corrected that. Staining on DOC could have been old. Just thought I'd throw that out there.

[tariqzai]

(04-17-2020 )JimT Wrote:  You mentioned that the doser injector was recently replaced. You may want to remove it from the exhaust elbow and double check that the gasket was put on correctly. I remember a pic Rawze shared of someone's doser where the gasket was misaligned and blocking most of the fuel spray. There is also a "thermal isolator" that shrinks over time. If it wasn't replaced with a new one when they did the doser then it could be affecting the performance. Likewise if the assembly wasn't properly torqued down there could be a bad seal letting air into the system. If there is an exhaust leak somewhere before the DOC then the fuel could be igniting prematurely. Just another reason to double check that doser.

Of course, you might want to double double check that the readings are coming from the correct location. If you have a thermal imaging camera then you can verify not only the correct locations getting hot, but also the approximate temp readings. Double check the wires and make sure everything is plugged in to the right locations. On my system the plugs only mated to the matching connector, but the temp sensor could have been screwed in to the wrong hole. --- I know you said you checked this already, but sometimes silly mistakes like this can be the easiest to miss.

Finally, the pictures above show what looks like orange coolant spots getting on to the DOC and partial clogging of the DPF (hence the off center soot buildup). DPF could have been a result of ash buildup so a cleaning might have corrected that. Staining on DOC could have been old. Just thought I'd throw that out there.

Thanks JimT, I pulled the new dosser injector out and replaced it with another one that I had and which I new worked fine in my other truck, new gasket and thermal isolator, so far I have also replaced IMAP, EGR Temp, back pressure, DPF out let/intake, catalyst temp sensors, calibrated VGT, replaced exhaust manifold all gaskets, cleaned and checked for flow DPF and DOC filters at International dealership and mounted with new gaskets, EGR valve cleaned and gasket and seal replaced, also inspected egr valve physically to make sure it opens and closes. The forced regen still shows the DOC temp close to the DPF intake temp and the DPF outlet temp stays around 550-600 but the new thing is that forced regen gets terminated now and throw 2 codes, differential pressure values above normal and VGT mechanical not responding. Insight showing DPF differential pressure zero since I have got the filters cleaned. I am going to replace the VGT today and see if that works.

[tariqzai]

Replaced the VGT and now force regen suspended throwing two faults; "DOC faceplug root cause unknown" and DPF differential pressure data valid but above normal range. I have noticed that even if the force regen is terminated the Dosser injector status stays ON, it stays on until close the window and restart the test. I have also checked the exhaust fumes for any oil contamination and found no oil spots on the cardboard that I hold behind turbo on exhaust pipe. i have inspected and cleaned almost everything related to emission system on this truck except replacing the DOC/DPF filters with new one. Do you guys thing it could be any fault on the ECM or truck side? Why is the dosser injector status stays ON when the regen has stopped. It stays on even if I suspend the force regen, could this be something electrical/softawer. I hate to get rid of the mandate and trying my best to keep it legal but looks like I dont' have any option. Any advise will be highly appreciated.