Leak detection for a vapor handling system

摘要

The engine or powertrain control module of a vehicle remains electrically powered after the engine is stopped and is used to assess whether there is a leak in the evaporative emissions control system. Fuel tank temperature and pressure data, as well as fuel level data, is analyzed over a brief period of time by module and, if ambient conditions are suitable, the vent on the fuel adsorption canister is closed by signal from the module. The system is thus sealed and the module then analyzes the system pressure changes over a second brief period as the fuel cools by heat loss to detect the vacuum that will occur if the system has no leak.