By John Smith
Anyone who has ever forgotten to tighten the gas cap on a family car will be familiar with emission-related onboard diagnostic (OBD) systems. They emerge in various forms, including a cryptic malfunction indicator light (MIL) on the dashboard, a pesky “Check Engine” warning and the detailed troubleshooting codes that are recorded for technicians in the service bay.
The world of heavy-duty trucking is about to become very familiar with these lights and all of their related sensors.
As of the 2010 model year, selected engines from each manufacturer will need to be equipped with a system that watches over emission-controlling components – from the exhaust gas recirculation (EGR) systems that reduce NOx, to the diesel particulate filters (DPF) that capture particulate matter before it escapes through a truck’s exhaust stacks.
Whenever a problem occurs, the related fault codes will need to be recorded by the engine’s electronic control module (ECM), and a new MIL will begin to glow on the dashboard. The new monitoring systems will even need to ensure that the sensors are working as they should.
It is the first step of a rollout that will emerge over several years.
At first, the new diagnostic systems will only be required on each manufacturer’s most popular engine families for on-highway vehicles with gross vehicle weight ratings above 14,000 lbs. (Navistar, for example, will need to include the new sensors and lights on its 11- and 13-liter MaxxForce engines. Cummins will add the equipment to its ISX Family 1 models, while Volvo will add it to the 13-liter D13). But by 2013, all on-highway engines will be affected.
“This phase-in is designed to spread over a number of years the development effort required by industry and to provide industry with a learning period prior to implementing the OBD requirements on 100 percent of their highway product line,” the Environmental Protection Agency (EPA) says in its regulatory announcement, noting how the changes should add little more than $60 to the cost of an engine.
California’s OBD regulations were approved by the EPA in September, and the new federal rules that were approved in December are largely identical to those that were unveiled by the California Air Resources Board (CARB). While the requirement is new, manufacturers will be able to use some existing sensors for the work.
“Many EGR systems have had these in place,” observed Greg Gillham, Detroit Diesel’s manager of onboard diagnostics, during a 2008 Technology & Maintenance Council seminar on the topic.
For example, look at a 2009 engine and you will find sensors that monitor whether EGR rates are too low or too high. But Detroit Diesel has added a sensor in the crankcase ventilation system specifically to meet the 2010 requirements.
“Cummins will continue to utilize existing sensors that are on both the engine and the Cummins Particulate Filter, as they are today,” Cummins on-highway market spokesperson Christy Nycz added in a recent interview, noting how affected equipment will simply include new temperature sensors on the selective catalytic reduction catalyst, and a new NOx-related sensor.
For Navistar, the new requirements will see the introduction of a new mass air flow (MAF) sensor to detect fuel quantities. “All other monitors will use existing sensors for detection of emission-related failures,” says service program manager Douglas McGill.
“OBD-like diagnostics have been in place ever since the introduction of electronic engines, so the concept of performing diagnostics is nothing new,” notes Steve Berry, director of government relations for Volvo Powertrain, the supplier of engines and transmissions to Volvo Trucks North America.
“These systems, however, will have to perform according to regulated standards, and report information according to specific protocol. The most challenging aspect is calibrating the diagnostic to illuminate the MIL (in the event of a component failure) before the emissions exceed a certain threshold, as established by regulation.”
MORE TO COME
But manufacturers will not need to include some of the refined sensors that were originally proposed…at least, not yet.
“In some cases, the technology that EPA or CARB wanted was not available, such as on the particulate matter side of things,” says Joe Suchecki, the Engine Manufacturers Association’s director of public affairs. “The sensor technology and way to do that has not been developed yet.”
This led the EPA to relax some of the NOx thresholds to levels that current technology could detect. “Some of the 2013 requirements – notably the DPF monitoring requirements – would require, we believe, a soot sensor with greater sensitivity and durability than what exists today,” the regulator notes in its official announcement. “However, we believe that they will exist in time for 2013 compliance.”
The new equipment will need to do much more than gather piles of data. Each system also needs to determine that the readings are accurate before illuminating the dashboard’s newest bulb. Out-of-range sensors, for example, will need to identify readings that don’t make sense, such as an ambient temperature sensor that insists the thermometer is reaching 200 F.
Rationality monitors will need to compare readings to other information that should come with them, such as an increase in boost pressure that should accompany higher engine torque.
The industry’s manufacturers have the opportunity to learn from similar experiences in other sectors. European truck engines already require diagnostic systems of their own, and automotive suppliers have incorporated such systems since the mid-1990s.
“Both the regulators and the industry have benefited from the automotive experience with OBD systems,” Berry observes. “Most important are the specific strategies by which failures are detected, but also the processes for developing and proving out the capabilities of the OBD system. As well, the communications standards for communicating signals and reporting information have matured considerably since the early days of automotive OBD.”
But there is no question that the heavy-duty systems will face the most demanding operating environments of all, Suchecki stresses. Warranties for the diagnostic equipment also will need to last five years. “There’s still a lot of development and work that has to be done.”
“The duty cycle and durability expectation in the heavy-duty environment is considerably different than typical automotive sensors. Materials and connectors for these sensors may need to be re-evaluated,” Gillham says. “The regulators are pushing very hard to introduce OBD in the heavy-duty industry as rapidly as possible, and this comes with many challenges.”
The good news for technicians is that the systems should make it much easier to troubleshoot issues with emissions-controlling equipment. The data that needs to be stored in ECMs should be able to identify challenges with a specific component, such as a stuck EGR valve that would allow an engine to emit too much particulate matter, or the higher intake temperatures on an EGR cooler that would allow the engine to generate too much NOx. It also should be able to determine whether a drop in exhaust pressure is linked to a cracked or melting DPF.
FEELING OUT FAILURES
Of course, there still will be challenges.
“There could be cases where the MIL is illuminated with no performance impact recognized by the driver,” Gillham says. “While the troubleshooting process will not be significantly different due to the introduction of OBD, dealing with these faults and ensuring that the issue has been resolved may be considered new to some technicians.”
The biggest challenge of all will emerge in coming years, as the sensors are asked to track ever-smaller variations between operating conditions and the regulated limits.
The more sensitive the diagnostics need to become, the greater the chance for a false reading, Cummins’ Ben Zwissler noted during last year’s Technology & Maintenance Council session on the issue. Manufacturers are all in the midst of testing programs to minimize such problems.
“These are handled by our engineering team using FMEA [Failure Mode and Effects Analysis] to make sure that only real failures are detected,” McGill says. And Nycz refers to her company’s ongoing field tests, stressing that “diagnostic algorithm designs that avoid false faults are an important part of our reliability plan.”
Quite simply, engine designers are stressing that the sensors will work as designed when the 2010 equipment rolls off assembly lines.
As should the diagnostic tools that also are required to read the emission-related fault codes on any make or model of engine.
Says Berry, “In general, this type of service support hardware, specifically the PC and USB PC-to-truck diagnostic connectors, are industry standard and widely available. The diagnostic software itself, however, generally is company or brand specific. This software is available to both dealers and independent service facilities, in compliance with the government’s SIR (Service Information Rule) for U.S. ’10.”
Manufacturers also are preparing training programs that will show technicians how to use these tools. Navistar, for example, plans to offer training over the Internet that will show technicians how to interpret any of the data and trip reporting information.
“As with the introduction of any new product, training of the service network is an important aspect of product introduction. U.S. 2010 engines will be no different in that regard,” Berry adds. “It’s true that emissions control systems are becoming more complex, but the tools and associated methods for diagnosing and correcting engine problems are not significantly different from a technician’s perspective.”
The engine will have a story to tell, Zwissler noted during the Technology & Maintenance Council meeting. “[You] will have to trust the engine to tell you what’s going on.”
And those who work with off-road equipment can expect a push for similar systems of their own.
“Having OBD systems and OBD regulations for non-road engines,” the EPA notes, “seem to be a natural progression.”
