Toyota Tundra. Manual — part 1386

Fig. 156: EVAP Pressure Graph - Purge VSV Stuck Closed

2. PURGE FLOW MONITOR

Fig. 157: EVAP Pressure Graph - Purge Flow Monitor

The purge flow monitor consists of two monitors. The 1st monitor is conducted every time and the 2nd
monitor is activated if necessary.



The 1st monitor

While the engine is running and the purge VSV is ON (open), the ECM monitors the purge flow by
measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd
monitor.

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra



The 2nd monitor

The vent valve is turned ON (closed) and the EVAP pressure is then measured. If the variation in
the pressure is less than 0.5 kPa-g (3.75 mmHg-g), the ECM interprets this as the purge VSV being
stuck closed, and illuminates the MIL and sets DTC P0441 (2 trip detection logic).

Atmospheric pressure check:

In order to ensure reliable malfunction detection, the variation between the atmospheric pressures, before
and after conduction of the purge flow monitor, is measured by the ECM.

OBD II MONITOR SPECIFICATIONS

1. Key-off Monitor

Monitor Strategy

MONITOR STRATEGY (KEY-OFF MONITOR) - OBD II MONITOR SPECIFICATIONS

Typical Enabling Conditions

TYPICAL ENABLING CONDITIONS (KEY-OFF MONITOR) - OBD II MONITOR
SPECIFICATIONS

Required Sensors/Components Purge VSV and canister pump module
Frequency of Operation

Once per driving cycle

Duration

Within 15 minutes (varies with fuel in tank)

MIL Operation

2 driving cycles

Sequence of Operation

None

EVAP key-off monitor runs when all of following conditions met -
Atmospheric pressure

70 to 110 kPa-a (525 to 825 mmHg-a)

Battery voltage

10.5 V or higher

Vehicle speed

Below 4 km/h (2.5 mph)

Ignition switch

Off

Time after key off

5 or 7 or 9.5 hours

Canister pressure sensor malfunction (P0451, P0452 and P0453) Not detected
Purge VSV

Not operated by scan tool

Vent valve

Not operated by scan tool

Leak detection pump

Not operated by scan tool

Both of following conditions met before key off

Conditions 1 and 2

1. Duration that vehicle driven

5 minutes or more

2. EVAP purge operation

Performed

ECT

4.4 to 35°C (40 to 95°F)

IAT

4.4 to 35°C (40 to 95°F)

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Typical Malfunction Thresholds

TYPICAL MALFUNCTION THRESHOLDS (KEY-OFF MONITOR) - OBD II MONITOR
SPECIFICATIONS

OBD II MONITOR SPECIFICATIONS

1. Purge Flow Monitor

Monitor Strategy

MONITOR STRATEGY (PURGE FLOW MONITOR) - OBD II MONITOR SPECIFICATIONS

Typical Enabling Conditions

TYPICAL ENABLING CONDITIONS (PURGE FLOW MONITOR) - OBD II MONITOR
SPECIFICATIONS

Purge VSV stuck open:

-

EVAP pressure when vacuum introduction complete Reference pressure x 0.2 or higher
Purge VSV stuck closed:

-

EVAP pressure change after purge VSV ON (open) Less than 0.3 kPa-g (2.25 mmHg-g)

Required Sensors/Components Purge VSV and canister pump module
Frequency of Operation

Once per driving cycle

Duration

Within 10 minutes

MIL Operation

2 driving cycles

Sequence of Operation

None

Monitor runs whenever following DTCs not present

P0011 (VVT System 1 - Advance)
P0012 (VVT System 1 - Retard)
P0021 (VVT System 2 - Advance)
P0022 (VVT System 2 - Retard)
P0102 - P0103 (MAF meter)
P0110 - P0113 (IAT sensor)
P0115 - P0118 (ECT sensor)
P0120 - P0223, P2135 (TP sensor)
P0125 (Insufficient ECT for Closed Loop)
P0171, P0172 (Fuel system)
P0300 - P0308 (Misfire)
P0335 (CKP sensor)
P0351 - P0358 (Igniter)
P0451 - P0453 (EVAP press sensor)
P0500 (VSS)

Engine

Running

ECT

4.4°C (40°F) or more

IAT

4.4°C (40°F) or more

Canister pressure sensor malfunction

Not detected

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Typical Malfunction Thresholds

TYPICAL MALFUNCTION THRESHOLDS (PURGE FLOW MONITOR) - OBD II MONITOR
SPECIFICATIONS

MONITOR RESULT

Refer to CHECKING MONITOR STATUS .

DTC P0443 EVAPORATIVE EMISSION CONTROL SYSTEM PURGE CONTROL VALVE CIRCUIT

DESCRIPTION

To reduce HC emissions, evaporated fuel from the fuel tank is routed through the canister to the intake manifold
for combustion in the cylinders.

The ECM changes the duty signal to the purge VSV so that the intake quantity of HC emissions is appropriate
for the driving conditions (engine load, engine speed, vehicle speed, etc.) after the engine is warmed up.

DTC DETECTION CONDITION AND TROUBLE AREA

WIRING DIAGRAM

Purge VSV

Not operated by scan tool

EVAP system check

Not operated by scan tool

Battery voltage

10 V or higher

Purge duty cycle

8% or more

Both of following conditions met

Conditions 1 and 2

1. EVAP pressure change when purge operation started

Less than 0.1 kPa-g (0.75 mmHg-
g)

2. EVAP pressure change during purge operation when vent valve
closed

Less than 0.5 kPa-g (3.75 mmHg-
g)

DTC

Code

DTC Detection Condition

Trouble Area

P0443

The proper response to the ECM command does not occur (1
trip detection logic).



Open or short in purge
VSV circuit



Purge VSV



ECM

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra