Let’s run this scenario: A regen is needed as a truck is en route to its destination.
You coordinate with your fleet manager, dispatch and your driver to schedule the needed regen. Everything has been communicated; you cross it off your to-do list and forget about it—until the truck rolls into one of your bays with a severe aftertreatment issue and now you’re looking hefty DPF or DOC costs.
So what happened?
The culprit might be over-use of the regen interrupt button, but how can you tell? The driver said he performed the regen as instructed… or did he?
Diagnostic data can give you an objective look at the use of the regeneration interrupt button. But before we get to that, let’s make sure that the aftertreatment service issue your technicians are diagnosis are symptoms of regeneration interrupt abuse.
“By interrupting the DPF regeneration the driver prevents the complete burn-out of the soot accumulated during normal driving,” said Dr. Barry Southward, vice president of catalyst technology for AP Emissions, at the company’s Aristo facility in Hobart, Ind. “The short-term impact will be that the residual soot retained in the DPF will continue to restrict exhaust flow through the DPF, resulting in a significantly higher backpressure than if the DPF is completely regenerated. This higher backpressure will increase parasitic losses for the engine causing an immediate decrease in fuel economy, a loss in engine power, a poor throttle response, will further decrease the performance of the DOC and DPF, and may even result in engine damage.”
The long-term impact?
“A decreased DPF lifecycle before cleaning or replacement, decreased DOC performance with associated potential emissions issues and perhaps most importantly, a significant increase in the risk of a catastrophic or ‘uncontrolled’ regeneration resulting in DPF cracking/melting or other failure,” Southward said. “The risk of DPF failure through excess soot accumulation/residual soot is a well-documented phenomenon that arises from the rapid combustion of excess residual soot within the DPF.”
So how do you correlate the service issue with the behavior?
Back to the data.
“The onboard telematics data can capture what percentage of the time the regeneration button is active, and the ‘active percentage’ of the interrupt button can be analyzed with failure occurrence for correlation,” said Darren Gosbee, vice president of engineering with Navistar Inc. “This data can be used by service to detect the possible abuse of the regeneration interruption button.”
