Evaporative emissions leak detection system and method utilizing on-vehicle dynamic measurements

A method of detecting a leak in an evaporative emissions system for a vehicle, the method comprising the steps of:

• establishing a threshold;
• measuring a physical disturbance of the vehicle with a sensory system and providing a sensory signal;
• comparing the sensory signal to the threshold and generating a diagnosis signal having a "valid test" state, when the sensory signal does not exceed the threshold, and generating the diagnosis signal having an "invalid test" state, when the sensory signal exceeds the threshold;
• setting another threshold;
• calculating a standard deviation of the sensory signal measured by the sensory system and then modifying the diagnosis signal to provide the "valid test" state, and an "invalid test" state, dependent on the another threshold;
• and
• executing an evaporative emissions system leak test while the provided diagnosis signal indicates the "valid test" state, and aborting the evaporative emissions system leak test when the diagnosis signal indicates the "invalid test" state.