Toyota Venza: Mass Air Flow Circuit Range / Performance Problem (P0101)

Toyota Venza Service Manual / 1ar-fe Engine Control / Sfi System / Mass Air Flow Circuit Range / Performance Problem (P0101)

DESCRIPTION

Refer to DTC P0102 (See page ).

DTC No.	DTC Detection Condition	Trouble Area
P0101	All of the following conditions are met (2 trip detection logic): (a) The engine is running. (b) The engine coolant temperature is 70°C (158°F) or higher. (c) The throttle position sensor voltage is 0.24 V or more, and less than 2 V. (d) The average engine load value ratio is less than 0.85, or more than 1.32 (varies with estimated engine load). Average engine load value ratio = Average engine load based on mass air flow meter output / Average engine load estimated from driving conditions (e) The average air fuel ratio is less than -20% or more than 20%.	Mass air flow meter Intake system PCV hose connections

DTC No.

DTC Detection Condition

Trouble Area

P0101

All of the following conditions are met (2 trip detection logic):

(a) The engine is running.

(b) The engine coolant temperature is 70°C (158°F) or higher.

(d) The average engine load value ratio is less than 0.85, or more than 1.32 (varies with estimated engine load).

Average engine load value ratio = Average engine load based on mass air flow meter output / Average engine load estimated from driving conditions

(e) The average air fuel ratio is less than -20% or more than 20%.

Mass air flow meter
Intake system
PCV hose connections

MONITOR DESCRIPTION

The mass air flow meter is a sensor that measures the amount of air flowing through the throttle valve. The ECM uses this information to determine the fuel injection time and to provide an appropriate air fuel ratio. Inside the mass air flow meter, there is a heated platinum wire which is exposed to the flow of intake air. By applying a specific electrical current to the wire, the ECM heats it to a specific temperature. The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to the mass air flow meter. The voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake air volume.

The ECM monitors the average engine load value ratio to check the mass air flow meter for malfunctions. The average engine load value ratio is obtained by comparing the average engine load calculated from the mass air flow meter output to the average engine load estimated from the driving conditions, such as the engine speed and the throttle opening angle. If the average engine load value ratio is below the threshold value, the ECM determines that the intake air volume is low, and if the average engine load value ratio is above the threshold value, the ECM determines that the intake air volume is high.

If this is detected in 2 consecutive driving cycles, the MIL is illuminated and the DTC is stored.

MONITOR STRATEGY

Related DTCs	P0101: Mass Air Flow Meter Rationality
Required Sensors/Components (Main)	Mass air flow meter
Required Sensors/Components (Related)	Crankshaft position sensor Camshaft position sensor Engine coolant temperature sensor Throttle position sensor
Frequency of Operation	Continuous
Duration	10 times
MIL Operation	2 driving cycles
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored	None
All of the following conditions are met	-
(Throttle position sensor voltage - (learned throttle position sensor closed position voltage + ISC voltage))	0.24 V or more, and less than 2 V
Time after engine start	5 seconds or more
Battery voltage	10.5 V or higher
Engine coolant temperature	70°C (158°F) or higher
Estimated load	30% or more, and less than 70%
Mass air flow meter circuit fail (P0102, P0103)	Not detected
Intake air temperature circuit fail (P0112, P0113)	Not detected
Engine coolant temperature circuit fail (P0115, P0117, P0118)	Not detected
Crankshaft position sensor circuit fail (P0335)	Not detected
Throttle position sensor circuit fail (P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135)	Not detected
EVAP system pressure sensor circuit fail (P0452, P0453)	Not detected
Leak detection pump fail (P2401, P2402)	Not detected
EVAP vent valve fail (P2419, P2420)	Not detected

TYPICAL MALFUNCTION THRESHOLDS

Both of the following conditions are met	1 and 2
1. Average engine load value ratio	Less than 0.85, or more than 1.32 (varies with estimated engine load)
2. Average air fuel ratio	Less than -20%, or more than 20%

WIRING DIAGRAM

Refer to DTC P0102 (See page ).

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) (See page ).

Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the Techstream on.
Start the engine and warm it up until the engine coolant temperature reaches 70°C (158°F) or higher [A].
Drive the vehicle at approximately 80 km/h (50 mph) to 112 km/h (70 mph) for 5 minutes or more [B].
CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

HINT:

Drive while keeping the engine load as stable as possible.
Enter the following menus: Powertrain / Engine / Trouble Codes [C].
Read the Pending DTCs.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: P0101.

Check the DTC judgment result.

Techstream Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform steps [B] and [C] again.

If no pending DTC is output, perform a universal trip and check for permanent DTCs (See page ).
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

CAUTION / NOTICE / HINT

HINT:

Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

1.	CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0101)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Enter the following menus: Powertrain / Engine / Trouble Codes.

(e) Read the DTCs.

Result	Proceed to
DTC P0101 is output	A
DTC P0101 and other DTCs are output	B

HINT:

If any DTCs other than P0101 are output, troubleshoot those DTCs first.

GO TO DTC CHART

2.	CHECK INTAKE SYSTEM

(a) Check the intake system for vacuum leakage (See page ).

OK:

No leakage from intake system.

HINT:

Perform "Inspection After Repair" after repairing or replacing the intake system (See page ).

REPAIR OR REPLACE INTAKE SYSTEM

3.	CHECK PCV HOSE CONNECTIONS

(a) Check the PCV hose connections (See page ).

OK:

PCV hose is connected correctly and is not damaged.

REPLACE MASS AIR FLOW METER

REPAIR OR REPLACE PCV HOSE

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