Power plays

by John G. Smith

NASHVILLE, Tenn. – The next generation of trucks built with the promise of cleaner exhaust will also deliver better fuel economy, and most available engine models will be certified to meet related standards a year ahead of schedule.
That should be welcome news for fleets and owner/operators who are struggling with high diesel costs.

The 2014 engines need to be 3% more fuel-efficient than their 2010 counterparts, while 2017 models have to be 5% better than 2010 designs.

Granted, duty cycles will still play a role in real-world results, much in the way that a car’s fuel economy is often different from the promises on a sticker in the vehicle showroom. The gains linked to the US Environmental Protection Agency’s 2014 emission standards will be measured through a tool known as the Greenhouse Emissions Model (GEM).

With that, regulators will be tracking improvements to Classes 7 and 8 trucks involving aerodynamic devices, low-rolling resistance tires, weight savings from wide-base tires and aluminum wheels, automatic engine shutdowns, vehicle speed limiters, and the engines which produce lower greenhouse gases.

“The EPA is not going to come knocking on your door asking for the carbon input for your fleet,” Detroit Diesel manager of technical sales and support, Vic Meloche, told maintenance managers during the annual meeting of the American Trucking Associations’ Technology & Maintenance Council. But there may be demands to maintain the equipment listed on a new Vehicle Certification Label found inside the driver’s door.

“You as a customer are expected to keep all this equipment,” he said. That means damaged aerodynamic devices would need to be repaired, and equivalent tires will need to be used. Some related engine parameters – such as speed limiters and a top speed of 105 km/h, and automatic shutdowns after five minutes of idling – may also be locked in place.

Then again, there is no enforcement of the rules at this point.

It isn’t the only equipment to be maintained. The aftertreatment systems such as diesel particulate filters (DPF), selective catalytic reduction (SCR) and diesel exhaust fluid (DEF) will be “here for the foreseeable future,” Meloche said.

Another emission-related change is taking place in the midst of it all. Requirements for on-board diagnostics (OBD) are introducing added sensors and warning lights to watch over exhaust-cleaning components.

“It does not make your engine last longer. It doesn’t make it run better. It doesn’t make emissions lower,” said Bill Kendrick, assistant chief engineer at Cummins. If anything goes wrong with the related components, drivers will be simply warned by an amber-coloured malfunction indicator light (MIL).

Some of the systems are already in place. The rules have been gradually introduced to specific product lines since 2010, and this year they apply to one rating in every engine family. But manufacturers expect to meet the standards with all diesel engines in 2013, three years ahead of schedule. (A deadline for alternative-fuelled engines follows in 2018).

“We expect to find a few bugs as we go to the market,” Kendrick said. “There’s a lot of software; a lot of codes.” Engine makers will actually tend to err on the side of caution and turn on the warning light more often than required, he said. “We want to make sure it comes on when it should.” But some of these issues will be addressed by replacing “virtual” sensors with physical versions.

Unlike the warning lights linked to DPF systems, these warning lights will not cause an engine to de-rate. But the light may offer an early warning of other problems to come, and those could cause the snail-like speeds.

The components will seem familiar to anyone who works on passenger cars, which have had the OBD systems since the 1990s, but the heavy-duty diagnostic codes, datalink protocols and connectors are all different.

The news of more regulations may still be discomforting to fleets that lived through earlier changes made in the name of cleaner air.

David McKenna, director of powertrain sales at Mack Trucks, had the unenviable task of listing equipment problems linked to earlier decrees by the US EPA, and it was a long list.

The last 11 years have seen the biggest changes in diesel technology since Rudolf Diesel created the first engine of its kind, McKenna said, referring to EPA mandates that came in 2002, 2007 and 2010. First came exhaust gas recirculation (EGR) systems to lower smog-producing NOx created in the combustion process. DPFs followed those, capturing lung-clogging flakes that would otherwise be released from an exhaust stack. SCR and tanks of DEF were introduced to transform remaining NOx into nitrogen and water.

New maintenance challenges emerged every step of the way, and with every nameplate.

“EGR challenged us all,” McKenna said. Coolers cracked in the face of demands to lower exhaust gases from 1,000 F to 300 F in a space of just 24 inches. Valves failed. Pitot tubes plugged.

The most common hardware-related complaints these days seem to be traced to DPFs. Delta pressure sensors have cracked, filters are plugging ahead of schedule, and fleets report unwanted spikes in the regeneration processes which transform trapped soot into ash. Many shops are cleaning the filters ahead of schedule – after as little as 325,000 kms of service – largely to spot emerging problems while the equipment is still under warranty. Meanwhile, engines are being de-rated to sloth-like speeds when “drifting” NOx sensors generate faulty engine codes.

Engineers have responded. The diameters of pitot tubes were enlarged to keep them clear. EGR coolers have been remounted to protect against cracks, and new software and upgraded sensors are addressing DPF challenges. The addition of DEF has also allowed earlier EGR rates to be lowered, reducing the strain caused by that process.

But fleets have a role to play in maintaining the equipment. “Follow the recommended guidelines for ash cleaning,” McKenna said as an example. He stressed the need to ensure engine software is updated, in a process that can begin as soon as a laptop or service tool is hooked up to the electronic control module. It’s not just about updates. Corrupt software codes can also be overwritten.

Meanwhile, service bulletins cover the maintenance of delta pressure sensing systems, care for the seventh injector, and other hardware-related upgrades. Specific fuel and oil filters, as well as fuel-water separators, may be recommended as well.

Any air in the cooling system has to be removed after the coolant is changed, and the pressure cap must sit properly in place, McKenna added. “In fact, make sure it’s the correct psi for the system.” A simple $150 refractometer was also seen as a valuable tool to measure unwanted water in any DEF.

And any solutions to maintenance challenges may be more than skin deep.

“Please, when you’re following a diagnostic tree, follow it right to the end,” McKenna said, referring to the fact that the root cause of an issue might still remain.

The solutions needed to meet emission mandates are not always simple.

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