In our last post on this subject matter, we talked about the strides the EPA is making in limiting emissions and the impact new technologies have on fleet owners and managers. To recap, when the EPA passed tighter standards to reduce the amount of nitrogen-oxide (NOx) that could be emitted from diesel tailpipes in 2010, engine manufacturers responded in kind. They introduced two technologies that enable diesel trucks to run cleaner and quieter without compromising diesel’s inherent efficiencies and advantages. 
Selective Catalytic Reduction (SCR) is an after-treatment approach that injects Diesel Exhaust Fluid (DEF) into the exhaust stream, converting NOx into nitrogen and water. Enhanced Exhaust Gas re-circulation (EGR) prevents NOx from being produced in the first place by suppressing its creation during combustion and cleaning up resulting particulate matter in the diesel particulate filters (DPF). While the DPF approach is less complex, it requires action on the part of drivers to prevent engine damage.
Preventing damage and disruption requires cleaning and regeneration
Chances are if your vehicle was built after 2007, it has a DPF filter. While DPF filters do a great job of keeping pollutants out of the air, they eventually have to be cleaned. With a DPF filter, a hydrocarbon doser injects fuel into the exhaust stream as a truck’s engine runs. The DPF filter captures diesel particles, soot and dust and prevents them from being emitted from the exhaust pipe. As the fuel passes through an oxidation catalyst, the chemical reaction generates heat, transforming soot into ash. However, that ash can build up. What’s more, the filter can be affected by failures of upstream engine components like fuel injectors, EGR valves, EGR coolers or the turbocharger, contaminating the filter with raw diesel, engine oil or EGR coolant. When particulate matter reaches a certain threshold, filters can clog. If they do, they resist exhaust flow and can interfere with engine operation. To prevent costly engine damage or even shutdown, drivers must regenerate the engines. This isn’t a complex or time-consuming process, but it is an essential one if you want to prevent disruption to your delivery routes and business. So, it’s essential that drivers know how to do it when indicator lights tell them to.
Here are the two ways drivers can regenerate diesel engines.
- Regeneration while driving (passive regeneration): Vehicles whose routes enable them to run at high speeds typically regenerate on their own. If the vehicle still needs to be regenerated, the driver can simply drive the vehicle at uninterrupted highway speeds for 20 to 30 minutes and the engine will automatically regenerate.
- Parked regeneration (active regeneration): Vehicles used for urban deliveries typically run at low speeds and may not produce exhaust temperatures that are high enough to regenerate the engine during operation. These vehicles typically require a timely parked (active) regeneration cycle to prevent permanent damage.
A parked regeneration typically entails pulling the vehicle over to the side of the road, turning off all accessories, putting the transmission in neutral, applying the parking break, pressing and releasing the clutch pedal and pressing and holding the regen button on the dashboard until the RPM increases. The process takes from 20 to 40 minutes. When the regeneration is complete, the lights on the dashboard go out.
When the dashboard lights up, it’s time to regenerate
So how do drivers know regeneration is required? Most 2007 or later-model vehicles come with DPF status lights that alert drivers when it’s time to regenerate. A solid DPF status light is the first indication drivers get that regeneration is required. A flashing DPF status light is a second warning that regeneration is required, and action should be taken immediately. Stay tuned for our next post on the subject where we’ll explore DEF. Written by: Mr. Mike Dennis, Group Director Maintenance Operations at Ryder. He is an operations professional with over 20 logistics, transportation and maintenance. Throughout his career, Mr. Dennis has played an active role in developing maintenance solutions.
