Cummins aftertreathment systems

[Engines&aftertreathment]

hello,

I,m working with cummins engines and aftertreatment systems. Doc & dpf
With insite we monitor the afterctreathment systems.

Currently we are working on a engine that has frequent regeneration.the engine has low doc inlet temperature 280 degrees.the turbo speed is high approx.10000rpm higher compared with same models and the air intake flow is 125kg/hr higher than normal. This data is measured during regeneration. We found also that there is a little after burning in the dpf.

Does anybody have sugestions and/or ideas what could causes this trouble?

Thanks

 

[heymccall]

With no idea which Cummins, low inlet temp and high turbo spool, I'd suspect, if it has one, the exhaust mounted diesel injector may have a delivery (spray or pressure) issue.

My C9.3 cat uses the priming pump (electric) to feed the fuel injector. Machine started and ran good but threw codes to indicate poor DPF operation. Volume tested injector and found poor output. Then measured pump output. Near zero.

 

[Engines&aftertreathment]

Pressure and spray pattern is checked and found ok.

Are there are also engines forum on internet where we can talk about this topic?

 

[BigWrench55]

Replace the filter for the crank case ventilation.

 

[old timer]

what is the model number?

 

[Engines&aftertreathment]

Crankcase ventilation filter was clean and in good condition

 

[old timer]

I think both those problems can be interconnected. Too much air thru the engine will lower the exhaust temperature, causing frequent regen (incomplete ash removal) A faulty VGT could be the problem. Check codes in Insite as well as trip monitoring, light loads could carbon up the VGT. That can also be monitored in Insite.
Hope this helps

 

[Engines&aftertreathment]

Hello old timer,

Thanks for your reply.

That sounds reasonable that the VGT is faulty in this case.
But normally when the VGT has high RPM the nozzle ring is closed and the temperature is rising.
Do you think/suspect the nozzle ring faulty and is open in our case?

Normally you should also suspect that this should create error codes but there are no error codes found via insite.
Maybe it is mechanical problem of sticking nozzle ring inside VGT and therefore no error

 

[Wes J]

Doesn't Insite show the VGT commanded and actual position? Can you compare to a know good engine?

 

[old timer]

Without knowing the model number or ESN narrowing it down might be difficult, but not impossible.
I was thinking about an internal failure of the VGT nozzle ring. I suspect you would find a code for over speed of the VGT with 10000 extra rpm. Generally speaking, added air flow will lower exhaust temps, therefore incomplete regens. That's where I would look first.
Sorry I couldn't narrow it down further

 

[funwithfuel]

Perhaps unwanted EGR. Have you checked the actuator. Maybe check upstream/downstream temps against percentage of EGR demanded.

 

[Engines&aftertreathment]

Actualy it is a komatsu engine. The after treatment system is similair to cummins and the VGT is the same only it is hydraulical actuated instead of electrical. Internal the VGT is the same. We can also connect with insite to the engine.
We have no error for VGT over speed. The 10000-15000 higher turbo speed we saw during service regeneration

 

[Engines&aftertreathment]

Hello Guys,
The VGT is replaced and the DOC inlet temp is rised by approx. 100 degrees. The turbo speed went back to normal and air intake flow went back to normal.
thanks for all your advice and help!