Vehicle powertrain control system

A vehicle comprising:

• a transmission having an input;
• an engine configured to generate and deliver torque to the input;
• a clutch configured to connect and disconnect the engine from the input, and to crank the engine during an engine start;
• and
• a controller programmed to,
• in response to a command to adjust a torque of the clutch during an engine start and a presence of a hydrodynamic lubrication condition of the clutch, drive a clutch actuator pressure to a first desired value, and
• in response to a command to adjust the torque of the clutch during the engine start and a presence of a mixed lubrication condition of the clutch, drive the clutch actuator pressure to a second desired value that is greater than the first desired value.

A vehicle comprising:

• a powertrain having,
• a transmission having an input shaft and an output shaft,
• an engine configured to generate and deliver torque to the input shaft, and
• a disconnect clutch configured to connect and disconnect the engine from the input shaft, and to crank the engine during an engine start;
• and
• a controller programmed to,
• in response to a command to start the engine via the disconnect clutch and a first condition of the powertrain, close the disconnect clutch, calculate the torque of the disconnect clutch based on a controlled torque at the output shaft, and map the relationship between the torque of the disconnect clutch and a clutch actuator pressure to adjust a first transfer function that represents the relationship between the torque of the disconnect clutch and the clutch actuator pressure, and
• in response to a command to control the torque of the disconnect clutch during a first engine start and the first condition, adjust the clutch actuator pressure according to the first transfer function to control the torque of the disconnect clutch.