Diesel Engine Aftertreatment Service Tips From Manufacturers

It’s probably no surprise to learn that many of the most common problems with diesel engines today involve aftertreatment systems. Recently, Fleet equipment discussed the causes of problems such as excessive regen activity and how to determine if the regen frequency with their engines is within a normally accepted range. Our expert panels also talked about how fleets can diagnose aftertreatment systems, the guidelines they should follow, and the tools available to them.

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Expert Group

  • Ryan Vaughn, Customer Support Manager, Cummins Inc.
  • Andrea Brown, Director of Product Management – ​​Complete Powertrain, Mack Trucks
  • Ashley Murickan, Product Marketing Manager, Volvo Trucks North America
Single module after-treatment system

Fleet equipment (EF): What are the most common aftertreatment system problems that can cause excessive regeneration activity?

Vaughn: The most common problem that can cause excessive refresh activity is when the duty cycle does not allow passive refresh events. When high idling times, frequent stop-start events, lack of consistent engine and vehicle speed, or light engine loads frequently occur in day-to-day operation, the Diesel Particulate Filter (DPF) is more likely to fill and stationary regeneration will be required. . If stationary regeneration is systematically delayed, more after-treatment problems occur. Additionally, any contaminants that make it downstream of the aftertreatment system can impact the overall health of the system.

Brown: The most common root cause we have seen for frequent regenerations is a heavy ash load on the DPF because the filter is not cleaned properly or at the prescribed frequency. Another potential reason for excessive regeneration activity is incomplete regeneration cycles which typically result from continually low exhaust temperatures during stop and go operations, or in cold weather where the system is not able to to maintain an elevated temperature long enough during the application cycle to complete the procedure.

There have also been a few instances of high silica content in the fuel causing frequent regenerations. Other possible causes may include poor fuel quality, poor DEF quality, poor DEF concentration, leaks in the exhaust stream, improper back pressure, and improper maintenance of aftermarket system components. processing.

murickan: In addition to incorrect consumption of fluids or coolant or a major system failure, excessive idle time and frequent starts and stops can have a direct impact.

New Generation Mack MP8HE

EF: How can fleets determine if their engine regeneration frequency is within a normally accepted range?

murickan: The regeneration frequency depends on the duty cycle. Stop-and-go city driving may have a higher regeneration frequency. Highway driving, with high exhaust temperatures, may have a lower regeneration frequency. Regeneration frequency also depends on fluids, including fuel, oil, and coolant. Any coolant consumption by the engine may increase the frequency of regeneration. The same goes for incorrect fuel or oil, or any engine stress or failure that results in increased oil consumption.

Other engine failures or maintenance deficiencies can also have an impact. EGR or fuel system component failures can lead to increased soot or fluid deposits on the DPF, causing an increase in regeneration frequency. Failure of the aftertreatment hydrocarbon injection system can interfere with normal operation, resulting in pending regeneration requests.

Vaughn: Fleets can determine if their engine regeneration frequency is within a normally accepted range by consulting OEM tools and running an ECM report. The key to regeneration frequency is to seek consistency between events and the frequency with which they occur on an engine hour basis. To determine the proper amount of time before cleaning or replacing the DPF, consult the owner’s and operator’s manual for the specific engine.

Brown: All regeneration and sublimation frequencies may vary depending on the specific application in which the vehicle is used. Applications where exhaust temperatures remain cooler may experience more frequent regeneration cycles. Cold weather settings may include automatic periodic heating modes that may look like auto-triggered regeneration and feel like frequent regenerations.

Next generation Turbo Compound engine from Volvo Trucks

EF: Do you advise fleets to have specific tools or technologies to diagnose problems with the aftertreatment system?

Vaughn: When diagnosing aftertreatment system problems, it is recommended that fleets follow the exhaust system diagnostic procedures in the Cummins Online Service Manual on QuickServe and use the Engine Diagnostic Program Cummins INSITE to validate ECM data. There are also technical service bulletins, error code troubleshooting guides, and the aftertreatment diesel particulate filter excessive automatic and/or stationary regeneration symptom tree.

Brown: The recommended tool for diagnosing Mack engines is our Premium Tech Tool, a Windows-based diagnostic application designed to test, calibrate and program engine parameters. The PTT has the ability to show what type of regeneration is being requested, as well as accumulated data from the DPF pressure sensors which can help diagnose a high ash load or other issues that would cause frequent regenerations.

murickan: Using the Volvo Trucks Tech Tool will help you understand the cause of the regeneration request. It is also important to collect data on the start of any increase in regeneration frequency and what preceded it, and to read and evaluate fault codes in the event of a fuel system failure. , EGR system, turbocharger, etc., and make sure all sensors are working. correctly.

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