We discussed the history of emission control standards and systems in Part 1.
Here, we'll cover other efforts that have improved or will further improve fuel economy. But, how do you manage the tradeoffs in these newer trucks that have increasingly more maintenance problems? There are ways to manage that maintenance downside, which you can jump to here.
Reducing Greenhouse Gases
Emission systems have changed little since 2010, though changes are coming soon to help the present components work more consistently. The stress in recent years has been on reducing greenhouse gases, or the CO2 that even perfect combustion produces. This has meant continual improvements in fuel economy.
Greatly improved aerodynamics, engine tuning changes, redesigned oil and water pumps that may even operate at various speeds to produce less drag, and even subtle changes in the timing of the valve events to increase the expansion of gases on the power stroke, have continually improved efficiency as engine design progresses. Volvo has an energy recovery system called turbo-compounding that uses a second turbine after the one at the back end of the turbocharger. The extra turbine drives the crankshaft directly through gears, and it enables the EGR system to work while actually improving fuel economy instead of reducing it.
Common-Rail Injection Systems
Common-rail injection systems came in, in most engines, by 2010. Volvo had a high performing unit injector system that was ultimately replaced with common-rail in 2017. Volvo, Cummins, and other engine makers have produced special combustion chambers that kill soot and allow higher compression. The result, via super-advanced aerodynamics, low rolling resistance tires, and engine "downspeeding" is better fuel economy than truckers of the 1990s ever dreamed of.
Common-rail produces full injection pressure even at low RPM. The result is diesels that can cruise at RPMs of 1,150 RPM at cruise speed or even lower. Volvo engines with turbo-compounding can cruise at less than 1,100 RPM. Combined with automated transmissions that always shift to the right gear to save fuel, the results can be spectacular.
What all this means is that, if you can manage to buy a newer truck with fuel economy specifications, it will likely pay for itself in reduced fuel consumption.
Maintenance Downside and How to Handle It
These tremendous improvements in fuel economy and lower emissions come with some maintenance problems. The complexity of the system means occasional minor troubles. Drivers will occasionally get a dashboard light indicating the engine needs attention.
The most common problem is a bad sensor of some sort, as making these systems consistently control emissions right means constant fine tuning based on data about things like pressures, temperatures, and oxygen levels‚ even Nox levels. The sensors that do this work are exposed to a hostile environment, creating occasional failures. Complex programming that makes sense of all this, called onboard diagnostics, makes diagnosis much easier than it might be.
Become Friends with Your Local Dealer or Shop
These problems need to be handled by a dealer or shop that has the right instruments to read data out of the engine ECM, as well as a service department operation where all trucks are diagnosed as soon as they come into the shop. This way, if all that is needed when you have a problem is a new sensor that can be changed easily, you can get back on the road quickly. This means you need to develop relationships with such dealers or shops and work with them consistently to get good, fast repairs.
Routine Maintenance
Other suggestions include diligent attention to routine maintenance of items like filters for the fuel doser that performs regenerations of the DPF, and another that ensures proper filtration of the Diesel Exhaust Fluid used in your SCR system. Also, use high quality Diesel Exhaust Fluid that meets all recommendations of the truck and engine manufacturer -- don't buy by price alone.
Use high quality engine oil with the lowest possible ash level to help keep the DPF clean. Remember that oil consumption will foul the DPF, so make oil and filter changes at the proper interval and use the best oil to minimize engine wear. Special low-ash oils are available to minimize DPF maintenance. Also, maintain the engine coolant to minimize wear.
If you've purchased a fleet truck with 300,000-500,000 miles on it, have the fleet set overheads after purchasing. Fleets often don't bother to make these settings by trading it before adjustments get too far off.
Setting Overheads
Other routine maintenance like setting the overheads that operate the valves and some injectors as frequently as recommended, or even more frequently, will help because the fuel will then burn more completely. If you've purchased a fleet truck with 300,000-500,000 miles on it, be aware that fleets often don't bother to make these settings and avoid doing so by trading it before adjustments get too far off. Having them set after purchasing a used truck would be smart. Always use the highest quality oil and fuel filters that meet all manufacturer specifications, too!
Emission System Maintenance
Learn about emission system maintenance that can help keep these systems reliable. You may be able to access online educational materials provided by the manufacturer of your truck. Consult your dealer for how to access such material. You may even be able to attend a factory class for a day or two. Just pulling crankshaft and camshaft sensors and cleaning them occasionally can help.
Emission System Maintenance Tips
- Replace all major sensors yearly like crankshaft and camshaft mentioned above and the temperature and pressure sensors to prevent failures. Sensors are cheap and normally simple to replace, while on-road failures are expensive.
- Avoid idling and gear your truck properly for fuel economy. This helps keep the exhaust hot enough to keep the DPF clear. Use diesel-fired heaters for heating the sleeper overnight instead of idling. Use a diesel APU or battery-powered AC unit for overnight air conditioning of the sleeper, not the big diesel.
- Use fuel additives to keep injectors clean and boost the cetane of your fuel. This will help minimize soot in the DPF as well, especially during cold starts.
With painstaking maintenance, you'll likely be able to keep a newer tractor on the road with little downtime while also making more money by getting more miles per gallon than you ever dreamed of in the past.
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