General The construction is changed to comply with the LEV-II evaporative emission regulations -A Charcoal Canister Canister Close Valve Vapor Pressure Sensor To Intake Manifold Purge Valve Tank Pressure Valve Restrictor Passage Air Filter The construction is simpler than the conventional vacuum type Evaporative Emission Control System

Reference General Conventional vacuum type -A Charcoal Canister Canister Close Valve Vapor Pressure Sensor To Intake Manifold From Air Connector Pipe Purge Valve ORVR Valve Pressure Switching Valve Tank Pressure Valve Air Inlet Valve Air Drain Valve

Location -A Charcoal Canister Canister Close Valve Vapor Pressure Sensor Purge Valve Tank Pressure Valve Air Filter Service Port Evaporative Emission Control System

Charcoal Canister -A Canister Closed Valve Tank Pressure Valve Charcoal Canister (3.0 liters) From Fuel Tank To Fresh Air Line To Intake Manifold Evaporative Emission Control System

Charcoal Canister –The vapor guide prevents the vapor gas without passing through the activated charcoal -A With vapor guide (’03 Tundra) Without vapor guide (Conventional type) Include vapor gas* To Intake Manifold From Fuel Tank To Intake Manifold From Fuel Tank Clean air Absorb vapor gas *: It will affect the air-fuel ratio control of the engine Vapor Guide Evaporative Emission Control System

Tank Pressure Valve Tank pressure valve controls the flow rate of the vapor gas from fuel tank to charcoal canister -A When refueling (Tank pressure is large) Tank Pressure Valve Vapor Gas (From Fuel Tank) From Fuel Tank Restrictor Passage Evaporative Emission Control System

Tank Pressure Valve The restrictor passage prevents the large amount of vacuum that is created during system monitoring from entering the fuel tank -A From Fuel Tank Restrictor Passage If the large amount of vacuum enters the fuel tank during system monitoring, system monitoring is not performed normally Vacuum

Air Filter The air filter prevents dust and debris in the fresh air from entering the system -A To Fresh Air To Charcoal Canister The air filter is maintenance-free Evaporative Emission Control System

Service Point Air Filter If the air filter becomes clogged, the ECM illuminates the MIL and record the DTC P0446 -A DTC P0446 is detected (Canister Closed Valve close malfunction) Canister closed valve is OK The air filter is clogging

System Operation Stored fuel vapors are purged from the charcoal canister when the purge valve is opened by ECM -A ECM OPEN To Intake Manifold Atmosphere Duty Stored fuel vapors Evaporative Emission Control System

System Operation When refueling, the fuel vapors enter to the charcoal canister and they are cleaned -A ECM Close OPEN The internal pressure increases The fuel vapors are Cleaned Evaporative Emission Control System

System Monitoring When the initial conditions are met, the ECM introduces a vacuum into the system and monitors system to detect system malfunction -A P1 Initial conditions are met P2 P1’ 0 mmHg Fuel Tank Pressure Purge Valve Canister Closed Valve The ECM monitors the amount of pressure increase in the fuel tank Open Close Open Close Value B Value A Evaporative Emission Control System

System Monitoring Step1 -A The ECM measures the amount of pressure increase (P1) in the fuel tank Fuel Tank Pressure Purge Valve Canister Closed Valve P1 0 mmHg 15 secs. P1 Close Evaporative Emission Control System

System Monitoring Step2 -A The ECM opens the purge valve and introduces a vacuum into the fuel tank Fuel Tank Pressure Purge Valve Canister Closed Valve Open Close Evaporative Emission Control System

System Monitoring Step3 -A Fuel Tank Pressure Purge Valve Canister Closed Valve Value B Value A Below value A The ECM measures the amount of pressure increase (P2)in the fuel tank P2 5 secs. Value B Close Evaporative Emission Control System

System Monitoring System leak judgment -A P2 Measurement P2 > Reference Value* Presumes presence of system leak P1 is small Judges presence of system leak *: Reference value is stored in the ECM P2 < Reference Value* Judges absence of system leak P1 is large Judges P1 again (P1’) Normal system control Evaporative Emission Control System

P1’ is small Judges presence of system leak P1’ Measurement The MIL illuminates and ECM stores the following DTCs in its memory Level of LeakDTC Very small, small or medium leak P0442 and/or P0456 Large leakP0441, P0442 and P0446 P1’ is large Repeats judgment

VSV Monitoring Normal condition -A PurgingSystem monitoring Purge Valve System leak judgment Canister Closed Valve Fuel Tank Pressure Open Close Open Close Evaporative Emission Control System

VSV Monitoring Purge valve open malfunction -A DTC P0441 is memorized, The MIL illuminates When the ECM is measuring the P1 value, the pressure in the fuel tank drops rapidly It remains in a constant, slight vacuum state Malfunction Judgment Purge Valve Canister Closed Valve Fuel Tank Pressure Normal Condition Open Engine Starting Evaporative Emission Control System

VSV Monitoring Purge valve close malfunction -A DTC P0441, P0442 and P0446 is memorized, The MIL illuminates Purge Valve Canister Closed Valve Fuel Tank Pressure Close Malfunction Judgment The pressure does not change No vacuum is introduced Evaporative Emission Control System

VSV Monitoring Canister closed valve open malfunction -A Purge Valve Canister Closed Valve Fuel Tank Pressure Open DTC P0441, P0442 and P0446 is memorized, The MIL illuminates Malfunction Judgment A slight vacuum is created It is not possible to completely introduce a vacuum Evaporative Emission Control System

VSV Monitoring Canister closed valve close malfunction -A Purge Valve Canister Closed Valve Fuel Tank Pressure DTC P0446 is memorized, The MIL illuminates Malfunction Judgment A large amount of vacuum is introduced Close Evaporative Emission Control System