A few things:
First the regen to keep with the topic. The regen is both "active" and "passive" meaning that at a certain point, irregardless of how much soot is built up, it will go into regen. This, on these newer LS engines, is every 50hrs (check your manual). OR they regen when the sensors start noticing a certain percentage of soot buildup, it initiates a regen cycle. For example:
Hour Clock = 50hrs - Regen cycle
Hour Clock = 94hrs - Regen Cycle
Hour Clock = 144hrs - Regen cycle
At 50hrs, the computer started the regen and burned the soot. Probably was getting close, but it still did it. 44hrs later, at 94hrs on the meter, the sensor kicked off the second regen because the soot built up. Didnt quite make it to 100. But the next cycle, at 144hrs, did complete the 50hrs and was initiated by the computer.
There is a fantastic explanation made by PCABE5 linked here:
https://www.tractorbynet.com/forums/ls-tractor-buying-pricing/431409-mt342.html#post5853163
https://www.tractorbynet.com/forums/ls-tractor-buying-pricing/431409-mt342.html#post5853163
There are four different diesel emissions, Oxides of Nitrogen (NOx), Oxides of sulfur (SOx), Particulate Matter (soot) and Hydrocarbons (in the form of unburned fuel). The DPF controls spot but also has to deal with some sulfur oxides due to some sulfur content in diesel fuel. The system on the LS engine is consists of a Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) and is sometimes referred to as a close coupled system.
Regeneration is the process where soot particles trapped by the DPF (Diesel Particulate Filter) are burned into ash (De-soot) and oxides of sulfur are burnt (De-SOx). This process involves a lot of different components as well as a program in the ECM triggered by the pressure differential sensor or by an internal counter.
First, there are three types of regeneration ‐ Passive, Active and Manual:
• Passive regeneration can occur when the engine is operating under load conditions that generate high enough exhaust temperatures to oxidize the soot particles trapped in the DPF.* Most will never see this as temperatures in the DPF will not get hot enough.
• Active regeneration occurs when the exhaust temperature is insufficient to achieve passive regeneration. Under certain conditions the ECM can automatically activate the fuel injectors to raise the exhaust temperature to achieve a successful regeneration. The ECM activates the injectors post‐combustion when the exhaust value would be open.
• Manual regeneration can be performed with a service software or button on the dash.
The ECM will start the regeneration process of the DPF if the soot load exceeds a calibrated value. The ECM determines the soot load of the DPF based on the voltage output of the pressure differential sensor. Or the ECM has an internal counter that runs anytime the engine is running. This counter is engine RPM and exhaust temperature dependent, so the more RPM the engine is turning, the faster the counter runs (think using more fuel). When this counter reaches it's value, or the DPF reaches a soot load of XX grams, the ECM will try to activate the regeneration process. This is the active part of the regeneration process. I haven't looked through the software enough to view the counter but it appears 50 hours is the magic number that the ECM will not exceed.
The two processes that are involved in a regeneration event are, De‐soot and De‐SOx.
The oxidation of diesel particulate matter (soot) begins at 1025 degrees Fahrenheit, oxides of sulfur (SOx) oxidation begins at 1185 degrees Fahrenheit. Since a lot of tractors never get worked hard enough to raise the exhaust temperature high enough to reach the threshold, a passive regeneration will never be achieved. These tractors will have to depend on the active regeneration process.* The active regeneration process on the LS XR/MT tractors runs at about 1200+ degrees Fahrenheit there by burning both soot and sulfur.
Now, for tractor-trailers.
My history with this is two fold. I grew up driving trucks on the farm. I got a job for a local contract hauling company driving old Freightliners (with sleepers, my hotel room). We hauled everything, including making runs down to Oregon for Christmas trees. But mostly farm products to terminals or warehouses. I got contracted to haul apples from North Central Washington to a cold storage warehouse 30 miles from the orchard. My home was 3 hours away from there. I quit that job and drove OTR for another, larger, company that was very much long haul in new Volvos. I didn't like the automatic transmissions either. Least not until I was in thick traffic jammed up on the interstate.
Trucks idled "back in the day" or with older trucks to keep warm, or cold inside the cab. To provide power and to, well, sleep better. Nothing puts me to sleep better than the drone of a diesel engine.
But then, some people started noticing that all these trucks, lined up in neat rows at truck stops, are spewing TONS of unfiltered diesel emissions into the atmosphere, and dang it, we gotta do something!
Now, I'm all for helping the environment when and how I can. I dont litter, I dont dump chemicals onto the ground, etc. But these people are probably the same ones who look at cows and all they see are farts.
So the EPA came along... truck manufactures had to comply with regulations. Some of it is good, others, meh. Some truck stops, you cannot 'idle' your truck at all, but have window HVAC units with shore power. Other trucks might have APU's (generators) that run all that.
That old Freightliner that I drove, I had a hand throttle located just under the steering column. When I parked and left the engine running, I'd use that to bump up the RPM to about 1000 from low idle. This helped keep my oil pressure up and engine warm, especially in the winter. That truck would sometimes idle at 1000RPM all day! Never hurt a thing.
Kind of miss those days.
I quit driving truck to become a 'family man.' I know, you can have a family and be a OTR driver. But the pay sucked, and I was gone A LOT! That wasnt fun. So I quit and went to school. Now I drive a desk... kinda. Its more of a microscope that looks like a transformer. Get paid very well, work 4-10 and home every night. Cannot beat that with a thumper.
The more we know going in the better and more efficient we can be.
