Cylinder Deactivation (Active Fuel Management) System Description (LT1): Notes
To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the cylinder deactivation system ON to deactivate engine cylinders 1, 7, 6, and 4, switching to a V4 mode. The engine will operate on 8 cylinders, or V8 mode, during engine starting, engine idling, and medium to heavy throttle applications.
The conditions listed below determine when cylinder deactivation is enabled.
- Engine has been running for greater than 30 s
- Engine speed is between 700 and 2800 rpm
- Engine oil pressure is between 187 - 455 kPa (27 - 66 psi)
- Engine coolant temperature is between 40 - 129°C (100 - 264°F)
- Engine oil temperature is between 16 - 128°C (61 - 263°F)
- Throttle angle is 6% or less
- Ignition voltage is greater than 11 V
- Transmission is not in first, second, or reverse gear
- Vehicle speed is greater than 25 kph (15.5 mph)
- Brake booster pressure is greater than 42.0 kPa (6 psi)
- Vehicle is not in fuel shut off mode
- Vehicle is not in heater performance mode
- Vehicle is not in tip in bump acceleration mode
- Vehicle is not in oil aeration mode
- Vehicle is not in low range (if equipped)
When cylinder deactivation is commanded, the ECM will determine what cylinder is firing and begin deactivation on the next closest deactivated cylinder in firing order sequence. For example, if cylinder number 1 is on its combustion event when cylinder deactivation is commanded ON, the next cylinder in the firing order sequence that can be deactivated is cylinder number 7. If cylinder number 5 is on its combustion event when cylinder deactivation is commanded ON, then the next cylinder in the firing order sequence that can be deactivated is cylinder number 4.