diesel engine exhaust traps

[mechanic6]

i have run into some curious operating problems with diesel engine exhaust particulate trap equipment.
one is in a fleet of smaller buses used in short run(2 or 3 mile loop,16 hours per day)
the exhaust does not get hot enough,so the engines are going into "regen" mode,and require us to put them in the shop with the laptop hooked into the ECM .
we have had to do this about every 50 hours or so,needless to say its a pain you know where.
we have 5 of these LEHM (low emission high maintenance)busses,so it bites into our manpower a lot.

local Cummins dealer is sympathetic but no long term solution but "put up with it"

any ideas?

 

[patdaly]

You have to manually place them in Regen mode? At least on the 6.7 units for the light truck market that is all handled by the ECM. Perhaps the manufacturer of the chassis would be the place to ask.

 

[BrianPetersen]

Is there any way you can incorporate a 15 - 20 minute highway run (or whatever is enough to initiate a regen) once a day? Even if it's outside the normal run, it might be cheaper than having to do something special in the shop.

I find it odd that a laptop would have to be connected.

 

[WGJ]

It is odd, isn't it?
I thought that the need for regen was flagged by the delta pressure sensor indicating a particulate filter pressure drop above a level calibrated into the ECM, then the ECM strategy setting off a fueling regime aimed at getting the exhaust gas temperature increased and filter regeneration going.

Bill

 

[Lou Scannon]

It sounds like your duty cycle is pushing the envelope for their system, and they know it.

 

[mechanic6]

hi
thanks all,hemi you are correct,the duty cycle is not getting the exhaust hot enough to self clean.
we cannot alter the duty cycle,and taking them out of service for a highway run is not practical.

the exhaust PCA and engine controls work as they should,i guess what i am after is how to get around this without removing the system.
there is not much that the OEM(Cummins) can do,and the chassis maker just assembles the components so no help there.

if anyone else has been having this problem let me know.

Ken

 

[MikeHalloran]

Have a marine exhaust shop make insulating blankets for the cans. That should get the temperature up some, probably shorten their life a bit, and probably void your warranty, but it may get the maintenance costs down to a merely unreasonable level. You'll know the blankets are working when they fall apart pretty regularly. Expect some (acrid) smoke for the first hour or so.

It shouldn't shorten the cans' life a lot, unless the duty cycle does change to include some high load time, in which case the cans may work without the blankets.

My first experience with particle traps was on generators that couldn't run 50 hours without disassembly and mechanical cleaning, even when artificially loaded. Yeah, ironic; you had to burn triple the fuel you actually needed in order to keep the emission control kluge barely working.

I get the impression that the technology is slowly getting better, but its public face includes _way_ too many optimists.



Mike Halloran
Pembroke Pines, FL, USA

 

[Andreb]

Not to change the subject but it looks like you have the perfect route for a series hybrid diesel/electric.

 

[EdDanzer]

Since the bus and engine manufacture won’t help you could turn the filter elements into a resistance heater or install a propane tank and burner to burn the particulates. If a temperature sensor and controller are use it could cycle on and off as required.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com