Keeping Flexible with New Electronics

What your technicians need to know about electronic controls on clean diesels and flex-fuel vehicles.

“It was primarily a refinement of the control algorithms and the calibration,” he says. “The big change for 2007 is this diesel particulate filter. The particles of soot get trapped in the walls and then periodically we go through a process called regeneration in order to incinerate that soot, and it burns it up and turns it into harmless gases. So the basics of the engine control system were there—we had to make some slight modifications to them in order to carry out this regeneration process.”

To avoid unnecessary maintenance issues, Frincke says if your fleet uses Duramax or other “clean diesel” engines, using the specified fuel—ultra-low sulfur diesel—and oil is essential.

“(Ultra-low sulfur diesel) has a maximum amount of sulfur—15 parts per million—and the previous generations over diesel had 500 parts per million,” he says.

Frincke says CJ-4 engine oil is also preferred in clean diesels because it burns less frequently, so less ash will collect in the particulate filters.

Ed English, vice-president and technical director for Flowery Branch, GA-based Fuel Quality Services, Inc., says electronic systems on older engines will not be as sensitive to lower or higher sulfur issues as compared to new models.

“That’s been borne out in discussions I’ve had with folks involved in the military, where they have diesel engines designed to run on JP-8, which is a high sulfur concentration,” he says. “Some of their newer engines that meet the new mission control standards, tend to have problems running on JP-8.”

Since the new ultra-low sulfur fuel is more stable than its predecessor, there should not be problems with fuel quality or variability, he says.

“With low sulfur diesel, there was some variability as far as stability, and that could have been giving some of the maintenance folks some problems with reliability and consistency,” he says.


While fleets might be moving toward more flex-fuel and clean diesel vehicles, the maintenance challenges for technicians remain about the same; with a few changes. Understanding electronics and computers is still the bottom line.

Like most parts of a vehicle, flex-fuel and clean diesel engines are becoming more computerized and more sophisticated. Without physical sensors to measure fuel capacitance, technicians who used to rely on the “hands-on” approach will need to understand how new virtual sensors work and how to use them to locate and fix the inevitable trouble spots.

Knowing a vehicle’s software and being able to properly use scanners is the best way to keep on top of maintenance issues. If your technicians are up to speed on these tools and procedures, and are making sure your vehicles are running on the right blend of fuel, it will help keep your vehicles out of the shop and keep them rolling down the road and making you money for as long as possible.

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