Mission: Accomplished

Whatever happened to the '02 emissions 'train wreck?' After some early stumbles, the '02 engines have proven themselves to be relatively trouble-free.


Fleet Maintenance continues its series of technical articles taken from the technician training presentations from the Fall Meeting of the Technology & Maintenance Council (TMC).

"There was all this hype about pre-buy and fear of the '02 product that was going to be introduced. And now (in September, 2004) we have all these '02 engines running around doing a real good job. It really didn't cause any huge technical hiccups going to this new platform."

These words from Bill Stahl, director of OEM service for Cummins, Inc., sums up the technical presentation given at the Technology & Maintenance Council's (TMC) Fall Meeting last September. Stahl, along with representatives from five other American heavy duty diesel manufacturers, gave a report on the state of "Troubleshooting Post-2002 Diesels," and the news was essentially positive.

In this issue, we'll cover the news from Cummins and Detroit Diesel, and next issue we'll continue with International and other manufacturers.

BILL STAHL, CUMMINS

According to Stahl, fleets have encountered some faults with early production ISX and ISM engines with EGR, but "they have not been mission-disabling."

Stahl went on to detail the technical issues that have been encountered, starting with EGR valve failures on some early engines. "Again, the saving grace was that it was not mission-disabling. It requires a very short period of time to change the EGR valve, and there were always parts available.

"The EGR valve also had a motor shaft problem (a stem seal that could leak), which was probably the worst problem, because you had exhaust gasses going up into the motor and gear box of the little control valve," he explained.

"There was also a sensor pin problem," he continued, "but the point was there were all of these little issues that contributed to the need to change the EGR valve. Most of those were solved in the last part of '03, and then we've made continual improvements up until the end of '04.

"I think the key point out of this list of problems-the EGR valve, the water pump, the injector, the exhaust manifold leakage, white smoke and stumble, the plugged differential tube-is that we came to the party with nine issues, and of those, none of them are mission-disabling," Stahl related. "And, other than the EGR valve failures, the rest of these aren't '02-technology related."

Technicians will notice additions to the ISX and ISM troubleshooting guides, according to Stahl. "When you add sensors, you add troublehooting logic, because you want to find if you have a bad sensor, a bad connection, a bad circuit.

"If it spits out a 432 or 438, it's a matter of the logic in Insite, or a paper fault tree that leads you through the process to fix that'" he said. "If you know the concept of reading a fault and going down through the fault tree to find a problem, once you do that for one fault, it's pretty much the same."

CHUCK BLAKE, DETROIT DIESEL

Chuck Blake, staff application engineer for Detroit Diesel, cautioned that "The EGR en-gine is a fairly complicated machine.

"It's a closed-loop control system, so it actually understands, for instance, EGR flow, so it keeps adjusting itself," he explained. "It's not just, 'At this RPM and at this load, I need this kind of angle on my EGR valve.' No, I want the exact flow that I require at this PRM and this load factor, so the engine continuously adjusts the turbocharger and the EGR valve to get the correct mixture into the engine. Consequently, the program controlling this engine has to be very smart; it's reading a couple more sensors than are normally on a diesel engine; it has to under stand atmospheric conditions better than the previous engine did. So there's a lot more brainpower going on, comprehending the ambient conditions and then satisfying the conditions that are needed to keep the exhaust system legal.

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