Torque Management

PURPOSE
Torque Management is a function of the Engine Control Module (ECM) that reduces engine power under certain conditions. Torque Management is performed for the following reasons:

^ To prevent overstress of powertrain components,
^ To limit engine power when brakes are applied, and
^ To prevent damage to the vehicle during certain abusive maneuvers such as shifting into gear at high throttle angles.

OPERATION
The ECM uses manifold vacuum, intake air temperature, spark retard, engine speed, engine coolant temperature, air conditioning clutch status, and Exhaust Gas Recirculation (EGR) valve position to calculate engine output torque. It then looks at torque converter status, transaxle gear ratio, and brake switch inputs and determines if any torque reduction is required. If torque reduction is required, the ECM retards spark as appropriate to reduce engine torque output. In the case of abusive maneuvers, the ECM may also shut off fuel to certain cylinders to reduce engine power.

POWER REDUCTION
The instances when engine power reduction is likely to be experienced are:

^ During transaxle upshifts and downshifts.
^ Heavy acceleration from a standing start.
^ If brakes are applied with moderate to heavy throttle.
^ If brakes are applied and brake booster vacuum is low.
^ When the driver is performing stress inducing (abusive) maneuvers such as shifting into gear at high throttle angles.

In the first two instances, the driver is unlikely to even notice the Torque Management actions. In the other three cases, engine power output will be moderate at full throttle. When the ECM determines that engine power reduction is required, it calculates the amount of spark retard necessary to reduce power by the desired amount. This spark retard is then subtracted from the current spark advance. In the case of abusive maneuvers, the fuel injectors for cylinders 1, 4, 6, and 7 will also be disabled for a period of time.