"I never was worried about EGR, but I can see how the prospect of it scared people," said James Pirie, one of the presenters on "Troubleshooting '02 Engines" at the Technology & Maintenance Council's Fall 2004 Meeting. Pirie, application engineer for engineering customer relations with International Truck and Engine Corporation, was addressing the widespread fear of exhaust gas recirculation (EGR) that swept the industry before the '02 engines were introduced.
JAMES PIRIE, INTERNATIONAL TRUCK AND ENGINE
"Honestly, I think there was a lot of hype in the trade publications that said, 'Oh my goodness, the sky is falling,'" he said. "To be honest, there were a lot of concerns about meeting the emissions requirements, outside of the EGR concerns, but I think the whole thing was a non-event."
Pirie went on to address some troubleshooting issues that fleets have experienced with International's '02 I-6 and V-8 diesels.
According to Pirie, some customers experienced a problem with turbo vanes not operating properly in the electronic variable response turbocharger (EVRT), resulting in a low power fault code. While not "EGR-specific," this problem involved the EGR system nonetheless, because, in Pirie's words, "It is an enabler for EGR. It's related to the turbocharger, but the only reason the EVRT is there is because of EGR."
"When you have EGR you have to have something that drives the back pressure," he said. "We call it EVRT, but the generic name is VGT (variable geometry turbo). We use the turbocharger to drive the EGR, and that's unique for this year's engine."
"The common occurrence is something that prevents free vane movement," Pirie explained. "Some of the early turbochargers had a nitriding process concern, that allowed them to, in some failure modes, accumulate a sufficient amount of corrosion to bind the mechanism." Nitriding is a heat-treating process to the iron to improve its durability, but a secondary aspect is the corrosion inhibitor.
"So in essence," he went on, "our correction for this has been a process change to the nitriding, that allows this nitriding to prevent the low cycle or failure mode from occurring, by protecting against this corrosion. In the simplest terms, it's a scale inhibitor, or a corrosion inhibitor."
Another early problem involved low power or a power surge on the V8 engine, Pirie explained. "It's cumulative, based on sooting, but some of this is corrosion on the unison ring that was redesigned."
"There were some clearances that were involved in the redesign of the unison ring, the ring that you rotate that has little slots in it that adjust the vane positions. There are little tabs that go in those slots, and all they really did was increase the clearances on the tabs and slots to prevent binding."
A Hard Start fault was sometimes mistakenly traced to an open injector circuit, Pirie said.
"You're trying to fix a circuit problem when in fact your batteries are low, and your IDM-that's your injector drive module-voltage is low," he explained. "The IDM measures this by looking at voltage deltas and so forth, so, even though it's not EGR-related, it's more of a technician aid to just look at some of the other impacts to circuitry faults that can inadvertently set the IDM code.
"If the voltage falls below a certain threshold, there isn't sufficient voltage to drive the ejectors, and it will set an injector fault. I encourage technicians to look for things that could cause low voltage to be associated with certain injector faults. If you've got those codes from 421 through 428, just be sure that your starting and electrical system is in satisfactory condition and supplying sufficient voltage to the modules. Just because you get those codes it doesn't necessarily mean it has to be an open injector circuit; it could be low voltage getting to the module."
Pirie also pointed out that certain International vocational engines have experienced unique EGR-related problems.
"There is a unique application consisting of airport ground support vehicles that we have addressed," he said. "The problem stems from continuously operating under very low load conditions. This tends to foul the Diesel Oxidation Catalyst. To address this, International offers an option restricted to airport vehicles that have speed limiters to prevent on-highway operation."
"You can never break that paradigm," he said. "In other words you can never have that truck drive on the road. Most airport vehicles, number one, they don't have anti-lock brakes so they're not allowed on the road; number two, they're generally never licensed for road operation; number three, part of our allowance for the off-road trucks is that we put a road speed limit on there, of an artificially low road speed, so that even if they drove it on the road they wouldn't want to. So what we do is, when you meet all the criteria we'll allow a recalibration of the engine for off-road use."
Although Pirie had not heard complaints from customers about a fuel-mileage penalty with EGR engines, he said he expected some fleets to experience a loss.
"I wonder about the fuel economy issue, because I don't think there's any question operating costs have got to go up. You'd expect that," he said. "You cut the NOx emissions in half, regardless of how you do it, regardless of what your technology path is, you cut the NOx in half and you're really cutting into that."
Still, Pirie believes that smart fleet operators can minimize the impact of EGR fuel economy loss by training drivers to get the most out of the engine.
"Your driver is always 10 percent of your fuel consumption, so operating the engine in a way that minimizes the speed and increases the torque is probably still a good idea," he said. "The regions of best fuel consumption are still the regions where EGR is minimized."
DAVID McKENNA, MACK TRUCKS
Vince Lindley, manager of fleet services for Mack Trucks, filled in at TMC for David McKenna, product manager, marketing for Mack Engines, Transmissions & Axles. We spoke with McKenna to get an overview of the presentation, and he offered these insights into early Mack ASET '02 engine issues:
Concerning problems relating to technicians inadvertently loosening the Mass Flow Tube, McKenna explained "The tube itself is held in place at each end with a high temperature viton-lined silicone hose with constant tension clamps and a supporting bracket located in the middle. So the tube is removable."
"The two sensors (1-temperature; 2-mass flow) are in fact welded to the mass flow tube, so they are not separately serviceable. I think the confusion may come from the previous arrangement that had the temp sensor that was not welded and the mass flow that was. In a few instances some technicians tried to remove the mass sensor and broke the weld, damaging the sensor, rendering it inoperative."
A common concern with EGR engines is what effect the new technology may have on oil drain intervals, since EGR introduces higher levels of soot into the engine.
"For the vast majority of Mack ASET AC engines, 25,000 miles is the recommended drain interval," McKenna said. "On our vocation ASET AI, the drain intervals are set at 16,000 miles or 300 engine hours, whichever first occurs. High humidity and dew points can have an affect on some vocational engine applications. Higher humidity and high idle times with transient duty cycles can sometimes result in additional soot loading of the engine oil. With the use of fully automatic transmissions, in refuse operations the drain interval is reduced to 250 engine hours."
GREG HOLDERFIELD, VOLVO TRUCKS NORTH AMERICA
Lindley also filled in for the engine expert from Volvo, and we recently checked in with Greg Holderfield, director of technical support service, Volvo Trucks North America to get a recap of their presentation.
"Soot is a product of the combustion process, and higher horsepower engines will produce more soot, since they burn more fuel," Holderfield said. "Volvo has addressed this with recommended oil formulas that have superior soot handling capabilities."
"Some early EGR temperature sensors experienced cracking," he went on. "This has been addressed by a change in our assembly process. We also instituted a service program to replace any affected sensors in the field, and this program has been completed."
"The Volvo EGR system does not shut down the engine when a fault occurs. However a fault code is logged and the fault may cause the engine to be de-rated to protect the engine. The unit could still be driven to a dealer for service.
"Customers have accepted Volvo's technology as reliable and dependable," Holderfield concluded. "The most important thing for dealer technicians to do before troubleshooting an EGR-related issue is to check the Volvo Dealer Communication System, since the issue may be covered by a current or open service program. Fleet technicians should check with their dealers for the latest information."
RICH BOWES, CATERPILLAR
"We've had issues here and there-there are a lot of new engineering concepts-but we resolved them pretty quickly, and our reliability right now is on a par with all of our earlier engine products," said Rich Bowes, continuous product improvement (CPI) supervisor, Caterpillar On-Highway Engines. Bowes recently followed up on the ACERT presentation given at TMC by Caterpillar's Bob Wessels.
"The primary diagnostic tool we have is Cat ET (Electronic Technician)," Bowes said. "It's a Windows-based program that runs off a laptop. If a technician has a laptop with Cat ET and the latest upgrades-the different service packs that come out with that-he connects to the truck's ECM, and he does all the troubleshooting from there."
"We have some new components, like VVA, the Variable Valve Actuation on the ACERT engines; Cat ET has a troubleshooting check for that," he said. "You can check for fault codes; you can do injector cut-out tests and see if there's one bad injector, for instance, if you have a rough idle; and you can re-flash the ECM with different software files from Cat ET. That's the predominant diagnostic tool we've had out for five or six years, so we continue to support that, and all the new software updates go to ET. So there are no additional diagnostic tools that you have to use on the ACERT engines versus any of the older engines.
"As far as troubleshooting, there are new fault codes that will show up on ET. If there's something wrong with the variable valve actuator, it'll give a couple different fault codes that you can read, and ET will tell you what those are, and then you can refer to our troubleshooting guides to see how to check what's wrong with it.
"With Variable Valve Actuation, there could be a wiring harness issue that affects those, there's debris that gets into the oil system that feeds them that causes problems sometimes," he said. "It could be a misadjusted lash setting; things like that are basically what occurs on them. Right now the units are not serviceable-you have to replace the entire assembly-but there are three assemblies, for instance, on a C15, so whichever one you find that's got the problem, you should replace that assembly."
"Beyond the use of ET, other troubleshooting checks are more basic. Typically we look for leaks in the exhaust system, exhaust manifold leaks, turbo leaks, and charge air cooler leaks are important to check for," Bowes concluded. "There are a little bit higher boost pressures with ACERT under certain conditions, so it's important that the charge air system is not leaking, so you're not losing boost."
