CERRITOS, CA – Isuzu Commercial Truck of America, Inc.’s two 2007 emissions standard-compliant diesel engines, the 4H and 6H, have been granted certification by the Environmental Protection Agency (EPA) and California Air Resources Board (CARB) for meeting government-mandated emissions standards.

The EPA requires that for all diesel engines manufactured after Jan. 1, 2007, nitrogen oxide (NOx) emissions must be reduced by approximately 50 percent and particulate matter emissions by 90 percent over the current standards, which were established in 2004 for diesel engines. To reduce nitrogen oxide levels, the 4H and 6H engines use an advanced Exhaust Gas Recirculation (ERG) system and a variable geometry turbocharger.

To reduce particulate matter emissions, a ceramic honeycomb channel Diesel Particulate Filter (DPF) was created to capture sulfate particles and soot. Exhaust gases are directed through the channels and a porous material, which traps the particulates. To clear the particulates and prevent clogging, a regeneration process occurs. The regeneration process, either self-regeneration or forced computer-initiated regeneration, burns off the trapped particulates and cleans the filter using high exhaust gas temperatures.

Self-regeneration is an automatic process that occurs as the vehicle is driven throughout the day and does not require driver involvement. Forced computer-initiated regeneration occurs if the vehicle operation does not produce exhaust gases hot enough for the automatic process to occur. A control light will alert the driver to active a dashboard switch to initiate the regeneration process. Special system sensing and control software was developed to precisely control engine combustion and DPF regeneration.

The Isuzu 4H engine is available in Isuzu N-Series vehicles and GMC and Chevrolet W-Series vehicles. The Isuzu 6H engine is available in Isuzu F-Series and H-Series vehicles, as well as GMC and Chevrolet C-Series and T-Series vehicles.