Subaru of America announced a service campaign this week focused on the 305-hp turbocharged 2.5-liter four powering the 2008 WRX STI. According to the verbiage on a letter sent to an owner, Subaru states that 'abnormal combustion' could occur when the engine is repeatedly or continuously operated above redline (6,700 rpm). At these high engine speeds, the Engine Control Module cuts fuel to the powerplant to protect the engine from even higher revolutions (this is common industry-wide, not just with Subaru). Unfortunately, under certain situations the Subaru 4-cylinder Boxer is still under high boost and the fuel cut-off causes the engine to run 'over lean' resulting in combustion that breaks piston ring lands... eventually destroying the engine.

Subaru's 'Service Program Campaign WVE15' reprograms the Engine Control Module software to improve combustion at engine speeds above redline, preventing engine damage. Subaru is quick to point out that the revised programming 'will not adversely affect the peak performance' of the vehicle, so owners need not worry about the free campaign messing up their 0-60 sprints. Letters from Subaru will go out to owners in the next week or two.