![]() Instead of letting the fuel vapors escape into the atmosphere, which is harmful to the environment, the EVAP system disposes of them in a. Inside the fuel tank, fuel vapors build due to motion and heat. The ECM illuminates the MIL and sets the DTC (2 trip detection logic). The Evaporative Emission System (EVAP) is a system in your vehicle that stores fuel vapors, which then are directed into the engine to be used. If the pressure exceeds -1.057 kPa-g (-7.93 mmHg-g) 4 seconds after the leak detection pump is turned ON, the ECM interprets this as the vent valve being stuck closed. The EVAP system pressure is then measured by the ECM, using the canister pressure sensor, to determine the reference pressure. In operation B, the leak detection pump creates negative pressure (a vacuum) through the reference orifice. Operation C: EVAP System Pressure Measurement Vent Valve: OFF (vent) Canister Pump Module Operation A: Atmospheric Pressure Measurement *: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize. If stabilized system pressure higher than second reference pressure, ECM determines that EVAP system leaking.Ītmospheric pressure measured and then monitoring result recorded by ECM. Large increase indicates normality.Īfter second reference pressure measurement, leak check performed by comparing first and second reference pressure. Purge VSV opened and then EVAP system pressure measured by ECM. If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor. Write down measured value as it will be used in leak check. Negative pressure (vacuum) created in EVAP system, and EVAP system pressure then measured. Vent valve turned ON (closed) to shut EVAP system. In order to determine reference pressure, leak detection pump creates negative pressure (vacuum) through reference orifice and then ECM checks if leak detection pump and vent valve operate normally. If pressure in EVAP system not between 76 kPa-a and 110 kPa-a (570 mmHg-a and 825 mmHg-a), ECM cancels EVAP system monitor. Vent valve turned OFF (vent) and EVAP system pressure measured by ECM in order to register atmospheric pressure. If it is still not below 35☌ (95☏) 7 hours after the ignition switch is turned OFF, the monitor check starts 2.5 hours later.Īctivated by soak timer 5, 7 or 9.5 hours after ignition switch turned OFF. *: If the engine coolant temperature is not below 35☌ (95☏) 5 hours after the ignition switch is turned OFF, the monitor check starts 2 hours later. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure. if the fuel tank is near empty or completely full, many of the basic tests will not run at all. some systems, especially the evap system, need to have a specific level of fuel in order for the tests to be trusted. have the fuel tank between 30 and 70 percent full. 5 hours* after the ignition switch is turned OFF, the leak detection pump creates negative pressure (vacuum) in the EVAP system. step one: double check vehicle preparation. Depending on where the leak is in the system and whether or not there is another damage, you can expect to pay up to 600 or so to fix a leak in your vehicle’s EVAP system.
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