Outline Of Diagnosis
Check if there is a leakage in fuel system or not, and perform the function diagnosis of valve.
In this system diagnosis, check for leakage and valve function is conducted by changing the fuel tank pressure and monitoring the pressure change using the fuel tank pressure sensor.
When in 0.04 inch diagnosis, perform in the order of mode Z → mode A → mode B → mode C and mode D; When in 0.02 inch diagnosis, perform in the order of mode A → mode B → mode C → mode D and mode E.
0.04-inch Diagnosis
0.04-INCH DIAGNOSIS MODE DESCRIPTION
| Mode | Mode Description | Diagnosis Period |
|---|---|---|
| Mode 2 (Purge control solenoid valve opening failure diagnosis) | Perform purge control solenoid valve opening failure diagnosis from the size of tank pressure variation from diagnosis start. | 3 - 16 seconds |
| Mode A (Estimated evaporation amount) | Calculate the tank pressure change amount (P1). | 10 seconds |
| Mode B (Sealed negative pressure, large leakage judgment) | Decrease the pressure in the tank to the target value by introducing intake manifold pressure to the fuel tank. If the tank pressure cannot be reduced, it is diagnosed as large leak. | 5 - 25 seconds |
| Mode C (Pressure increase check, advanced OK judgment) | Wait until the tank pressure returns to the targeted pressure (start level of P2 calculation). If the tank pressure does not become the value, make advanced OK judgment. | 1 - 15 seconds |
| Mode D (Negative pressure variation measurement, evaporation leakage diagnosis) | Calculate the tank pressure variation (P2), and obtain the diagnostic value using P1 found in Mode A. Perform the evaporation diagnosis using the diagnostic value. | 10 seconds |
Mode Table for Evaporative Emission Control System Diagnosis
EVAPORATIVE EMISSION CONTROL SYSTEM DIAGNOSIS CHART
| Mode | When normal | Diagnostic item | DTC |
|---|---|---|---|
| Mode Z | Roughly same as atmospheric pressure (Same pressure as 0 kPa (0 mmHg, 0 inHg)) | Purge control solenoid valve is judged to be open. | P0457 |
| Mode A | Pressure is in proportion to amount of evaporative emission. | - | - |
| Mode B | Negative pressure is formed due to intake manifold negative pressure | Large leak | P0457 |
| Mode C | Reaches target pressure | - | - |
| Mode D | Pressure change is small. | EVAP system large leak [1.0 mm (0.04 in)] | P0442 |
0.02-inch Diagnosis
0.02-INCH DIAGNOSIS MODE DESCRIPTION
| Mode | Mode Description | Diagnosis Period |
|---|---|---|
| Mode A (0 point compensation) | When pressure in tank is high, wait for 0 point (Near 0 kPa (0 mmHg, 0 inHg)) to return. | 0 - 12 seconds |
| Mode B (Negative pressure introduced) | Decrease the pressure in the tank to the target value by introducing the intake hose pressure to the fuel tank. | 0 - 27 seconds |
| Mode C (Negative pressure maintained) | Wait until the tank pressure returns to the target (start level of P2 calculation). | 0 - 20 seconds |
| Mode D (Negative pressure change calculated) | Calculate the time it takes for the tank pressure to return to the P2 calculation complete pressure. If the tank pressure does not return to the P2 calculation complete pressure, make advanced OK judgment. | 0 - 200 seconds |
| Mode E (Evaporation generated amount calculation) | Calculate the amount of evaporation (P1). | 0 - 280 seconds |