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Diesel Particulate Filters: Separating Fact From Fiction

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Back in 2001, the U.S. Environmental Protection Agency finalized new emission standards for a broad variety of diesel-powered vehicles, including heavy-duty highway vehicles and personal pickup trucks. These new standards, which went into effect for the 2007 model year, require diesel vehicles to use diesel particulate filters (DPF) and other tools to achieve cleaner emissions.

It's a move that's generated mixed reactions among truck buyers, setting into motion a number of myths and misconceptions about DPFs and how they affect engine performance. The following sheds some well-needed light on DPFs while dispelling a few myths along the way.

Myth #1: You'll Spend a Lot of Time and Money on DPF Maintenance and Upkeep

Located in line with the exhaust, diesel particulate filters work by capturing particulate matter (commonly known as "soot") found in the exhaust stream. The captured soot is usually oxidized and burned to ash during the regeneration process, where exhaust temperatures can reach as high as 600 degrees Celsius.

Eventually, the leftover ash and other various deposits have to be cleaned out of the DPF. Most people assume that the cleaning process not only has to be done frequently, but that it's also expensive. In reality, the cleanup process isn't as expensive or frequent as you'd think.

Tom Berg from Heavy Duty Trucking Magazine recommends having the DPF filter cleaned every 50,000 miles or once a year, whichever comes first. However, most diesel engine manufacturers have their own specific schedules for DPF cleanings. For example, Cummins requires a thorough DPF cleaning for its medium-duty engines every 300,000 miles.

DPF cleaning services are also becoming more affordable as time goes on. A typical DPF cleaning can be done for around $250, with some independent shops charging less depending on the type of truck and the severity of the buildup.   

Myth #2: It Costs a Lot of Money to Replace a Failed DPF

Another common misconception is that a DPF filter can cost a lot of money to have replaced if it completely wears out or ends up damaged somehow. However, the cost of replacing a failed DPF has become more reasonable in recent years.

A typical OEM DPF costs around $3,000, with aftermarket and wholesale versions available at lower costs. As time goes on and as DPF technology matures, it's likely that the average cost of replacing a DPF will decline even more.

Myth #3: A DPF Puts a Drag on Your Truck's Fuel Efficiency

A major fear once shared among truck owners was that the introduction of DPF technology would cause poorer fuel economy, especially for vehicles that use active regeneration as opposed to passive regeneration. Not only does the engine spend a little more fuel on the active regeneration process, but the accumulation of ash also has a slight increase on exhaust back pressure, which is also a factor in fuel consumption.

Nevertheless, a recent study found that despite the exhaust back pressure increase caused by ash build-up, the use of DPF only raised overall fuel consumption by 2 to 3 percent. It's a far cry from the severe mileage drops that many truck owners have reported at the start of DPF adoption. It's also likely that the relatively small drop in mileage are being made up by other fuel-saving moves elsewhere, including the use of auxiliary power units (APUs) in some trucks.

In addition, much of the fuel consumption increases associated with DPF have been due to improper regeneration, poor maintenance and a higher-than-usual amount of soot that needed to be burned during regeneration. In response to these concerns, the next generation of DPFs will likely feature new technologies to help curtail excessive fuel consumption and improve overall performance.

For more information, contact a professional filter supplier, such as Williams Oil Filter Service Co.