Patent ID: 7017561

Claim:
A method of operating a compression ignition engine comprising: processing data indicative of engine load, when a result of processing data indicative of engine load discloses engine load in a low load range, fueling the engine to operate by alternative diesel combustion and passing recirculated exhaust gas through a first EGR cooler, but not a second EGR cooler, when a result of processing data indicative of engine load discloses engine load in a medium load range comprising loads greater than those of the low load range, fueling the engine to operate by alternative diesel combustion and passing recirculated exhaust gas through both the first EGR cooler and the second EGR cooler, and when a result of processing data indicative of engine load discloses engine load in a high load range comprising loads greater than those of the medium load range, fueling the engine to operate by conventional diesel combustion and passing recirculated exhaust gas through the first EGR cooler, but not the second EGR cooler.