Neutral Profile Correction And Non-Volatile Memory

Neutral profile learning is used at End of Line to learn profile correction via a series of one or more neutral engine rpm throttle snaps. This allows the Misfire Monitor to be activated at the Assembly Plant. A Test Tool command is required to enable this method of learning, so this method will only be performed by a Plant or Service technician. Learning profile correction factors at high-speed (3, 000 rpm) neutral conditions versus during 60-40 mph decels optimizes correction factors for higher rpms where they are most needed and eliminates driveline/transmission and road noise effects. This improves signal to noise characteristics which means improved detection capability.

The profile correction factors learned at the Assembly Plant are stored into non-volatile memory. This eliminates the need for specific customer drive cycles. However, misfire profiles may need to be relearned in the Service Bay using a service procedure if major engine work is done or the PCM is replaced. (Re-learning is not required for a reflash.)

On selected vehicles, the neutral profile correction strategy is the only method used for profile correction learning. In the event of a loss of non-volatile memory contents (new PCM installed), the correction factors are lost and must be relearned. DTC P0315 is set until the misfire profile is relearned using a scan tool procedure.

The neutral profile correction strategy is available on most gasoline engine vehicles. It is not available on HEV and diesel engine vehicles.