theeld

I realize that DPF regeneration cycles are initiated by reading from the differential pressure sensor which measures DPF blockage. But does anyone know from experience if the cycles can also be initiated from accumulating mileage? Example: if no regeneration cycle has been intiated within the last 750 miles, one will be started. I am asking primarily due to my interest in the ml320 cdi, however i imagine it might be common accross all merceds vehicles which share the OM642 engine. M series, E series, and maybe more.

u001elg

That is an interesting question that I personally have never thought about...

One could also query if time is a trigger; as in, if no regeneration over 'X' hours of engine operation the regen cycle is initiated.

In either case, I am not sure what you would gain with this knowledge or how this would be used in your decision to purchase the ML.

Please give a little more information as to how this is relevant...

I will see if I can come up with a yea or nay as to any additional triggers for the regen cycle.

lkchris

An engine hour meter would be a better predictor than an odometer.

theeld

I ask because of the possible implementation of an off-road modification to remove the DPF while simulating the correct voltage signal to the ECU from the differential pressure sensor with a simple voltage divider circuit. I am curious if you could eliminate regeneration cycles completely with this method, or if time (engine hours) or odometer differences would still trigger regen cycles periodically.

Vernl

If you let your filter plug up...you essentially plug off your exhaust and you will lose power and stall...let us know how that works out for you

theeld

The filter will not plug up when you have removed it from the exhaust. I think you may have misunderstood.

u001elg

OK, now I am really confused. If you remove the DPF and install, if effect, a fixed resistance to make the computer think the differential pressure is within spec - why would you even care if the "regen" occurs... the DPF is gone!

The electrical connector would be unplugged (i.e. - to burn off any particulate on the non-existent DPF), so if voltage is applied it is to an open circuit. I can not see much less of a reason, if you are planning to defeat the DPF regen, to care what the trigger might be. Even if it did start a regen cycle over a given mileage or engine hour run time, how would this impact your proposed modification?

PS - all the information I have been able to review indicates that the regen cycle is based solely on the differential pressure across the DPF. A differential pressure outside the acceptable range (low or high) triggers the CEL and in effect will put the vehicle in limp mode until the fault is cleared.

theeld

The reason I care if a regen can be triggered by more than just the DPF blockage reading from the dpf sensor is thus: Regeneration cycles are not the easiest thing on an engine. High exhaust temp, and dilution of engine oil from what I read, so if the engine never did a regen again, that would be the best scenario I could think of. Of course, if the engine did a regen every once in a while but had no DPF that would still be prefferable to the stock setup.

u001elg

OK, now I understand...

I had read several articles and got advice to disable the EGR on my 1983 diesel due to the negative effects it would have. I never got around to doing that and 16 years and 409,000 miles later I traded the vehicle with no mechanical issues during the entire time I owned the vehicle.

There is a theoretical shortening of ultimate life, but I doubt that most normal driving will approach the time and mileage necessary to reap the benefits.

dgiturbo

Don't worry too much with the regeneration cycle. A while back I spoke with a tech who advises that the regeneration is accomplished by 1 extra pulse of the injector cycle. Your CDI uses 5 variable micro pulse width per combustion injection cycle under normal use, and regen makes it 6.
Definitely not enough to dilute your oil, and the exhaust system is built strong enough to handle the extra heat. Think how much heat a turbo generates.