Evaporative Emissions System: Testing and Inspection
Evaporative Emission (EVAP) System Leak Inspection- To verify that the problem has been fixed properly after repairs, the run drive cycle or EVAP system leak inspection must be performed.
EVAP system leak inspection using the WDS or equivalent
NOTE:
EVAP system test outline
- The EVAP system test, which can substituted for the run drive cycle as an EVAP control system repair confirmation method, can be done while operating the WDS in the KOEO (Key On Engine Off) condition instead of actually driving the vehicle.
EVAP system test description
- The EVAP system test finds gas leaks in the system using the PCM to monitor changes in the air pump load current of the EVAP system leak detection pump. This test starts after sending an on-demand test signal from the WDS to the PCM. The PCM controls the air pump and change-over-valve operation and also stores the load current of the air pump as follows:
i. The PCM commands turn the air pump on and retrieve the air pump load current value (LDP_MON PID) as a reference current (LDP_REF PID).
ii. After retrieving a reference current value, the PCM commands the change-over-valve to open, then captures the air pump load current value (LDP_MON PID) as idle current (LDP_IDL PID). The EVAP system will be pressurized from this phase.
iii. The PCM continues to monitor the air pump load current value (LDP_MON PID) until the end of the test.
- You can confirm whether any EVAP gas leak occurred or not by reading the test results.
EVAP system malfunction judgment
- The PCM calculates the stored air pump load current value and send the results to the WDS as DTCs.
Evaporative system test procedure
1. Select the EVAP system test from the Tool box on the WDS display and follow the instructions.
2. Verify that all of the given PIDs are within the specifications at the pre-test confirmation screen.
NOTE:
- To successfully perform this procedure, all PIDs must be within the following specifications before proceeding to the next step.
- The PCM will cancel the EVAP system test if the B+ PID value falls lower than 11.0 V during the test.
3. Start the engine.
4. Drive the vehicle or let the engine idle more than 20 min.
5. Turn ignition switch off, then turn it to the ON position again (Key On Engine Off).
6. Press the tick icon to start the test.
7. Verify that no DTCs present after the completion of the test.
- If any test result is indicated with red, diagnose the problem using the following DTC troubleshooting procedure or component inspection procedure.
- If any DTCs are detected, diagnose the problem using the appropriate DTC troubleshooting procedure.
EVAP system leak inspection using leak tester
1. Perform the following SST (EVAP System Tester 134-01049) self-test:
NOTE: If the tester does not work correctly during the self-test, refer to the tester operators manual for more detailed self-test procedure.
1. Verify that the control valve on the panel is in the HOLD position then open the nitrogen bottle valve.
2. Connect the vehicle interface hose (part of the SST) to the SELF TEST port located on the control panel. Hand tighten the fitting. (Do not overtighten.)
3. Turn the control valve to the TEST position.
4. The gauge should read 331 - 381 mm {13 - 15 in} of water.
- If the gauge is not reading in this range, adjust the pressure by turning the black knob on the low pressure regulator at the nitrogen bottle.
5. Turn the control valve to the HOLD position.
6. Verify that the gauge holds pressure and that the flow meter reads no flow.
- If there is no drop in pressure and no flow, the tester passes the self-test.
- If the gauge leaks down, refer to the operators manual.
2. Connect the SST to the vehicle.
1. Verify that the control valve on the panel is in the HOLD position then open the nitrogen bottle valve.
2. Remove the fuel-filler cap from the vehicle.
- If the fuel-filler cap is not a MAZDA part or equivalent, replace it.
3. Connect the receiver assembly (SST: 134-01059) to the vehicle cap test hose assembly (part of SST) and the fuel-filler cap from the vehicle.
4. Connect the cap adaptor (SST: 134-01058) to the vehicle cap test hose assembly (part of the SST) and to the fuel-filler neck.
5. Connect the vehicle interface hose (part of the SST) to the center fitting of the vehicle cap test hose assembly (part of the SST).
3. Connect the WDS or equivalent to the DLC-2.
4. Turn the ignition switch to the ON position (Engine off).
5. Request the PCM on-board device control (Mode 08) using the WDS or equivalent to close the change-over valve (COV) in the EVAP system leak detection pump.
NOTE:
- The COV is closed for 10 min unless the following any actions are done:
- The engine is started.
- The ignition switch is turned off position.
6. Make sure the control valve on the 134-01049 is in the HOLD position and that the valve on the cylinder of nitrogen gas is open.
7. Turn the control valve to the open position and let the system fill. You should note a drop in the gauge pressure along with the flow meter being pegged at maximum flow for several minutes depending on how full or empty the fuel tank is, and how long it takes to completely fill and pressurize the evaporative emissions system hoses.
8. If the gauge and the flow meter do not settle to a measurable level after 2-3 min, then refer to the Mazda Workshop Manual to verify that the cut or vent valve is properly closed.
9. Verify the pressure gauge and flow meter reading to determine if there is an evaporative emissions leak:
NO EVAPORATIVE LEAK:
- The flow meter registers "zero flow" and the pressure gauge returns to the pre-set pressure of 356 mm {14 in} of water (H2O).
EVAPORATIVE LEAK:
- The pressure does not return to the preset level of 356 mm {14 in} of water (H2O) when measuring the flow. See "SETTING LEAK STANDARD FOR TESTING" (.020 to .040 inch H2O) of the Evaporative Emissions Tester operators manual (134-01067).
NOTE: Turn the control valve to the HOLD position then disconnect the SST.