Toyota Tundra Service Manual: Mass Air Flow Circuit Range / Performance Problem (P0101)

Toyota Tundra Service Manual / Engine, Hybrid System / 1ur-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

Conditions (a), (b), (c), (d) and (e) continue for more than 10 seconds (2 trip detection logic):

(a) Engine running

(b) Engine coolant temperature 70°C (158°F) or higher

(c) Throttle Position (TP) sensor voltage 0.2 V or more and 2 V or less

(d) Average engine load value ratio less than 0.85, or more than 1.15 (varies with estimated engine load)

Average engine load value ratio = Average engine load based on MAF meter output / Average engine load estimated from driving conditions

(e) Average air-fuel ratio less than -20%, or more than 20%

  • Mass Air Flow (MAF) meter
  • Intake system
  • PCV hose connections
  • EGR valve assembly

MONITOR DESCRIPTION

The MAF 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 MAF 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 wire and internal thermistor. 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 MAF meter for malfunctions. The average engine load value ratio is obtained by comparing the average engine load calculated from the MAF 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 a 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 (CKP) sensor, Engine Coolant Temperature (ECT) sensor and Throttle Position (TP) sensor

Frequency of Operation

Continuous

Duration

10 times

MIL Operation

2 driving cycles

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present

P0102, P0103 (Mass air flow meter)

P0112, P0113 (Intake air temperature sensor)

P0115, P0117, P0118 (Engine coolant temperature sensor)

P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle position sensor)

P0335, P0337, P0338 (Crankshaft position sensor)

P0452, P0453 (EVAP system pressure sensor)

P2401, P2402 (Leak detection pump)

P2419, P2420 (EVAP system vent valve)

Throttle position (TP) sensor voltage

0.2 to 2 V

Time after engine start

5 seconds or more

Battery voltage

10.5 V or more

Engine coolant temperature

70°C (158°F) or more

Estimated load

30 to 70%

TYPICAL MALFUNCTION THRESHOLDS

Both of following conditions 1 and 2 met

-

1. Average engine load value ratio

Less than 0.85, or more than 1.15 (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

  1. Connect the Techstream to the DLC3.
  2. Turn the ignition switch to ON.
  3. Turn the Techstream on.
  4. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
  5. Turn the ignition switch off and wait for at least 30 seconds.
  6. Turn the ignition switch to ON and turn the Techstream on.
  7. Start the engine and warm it up until the engine coolant temperature reaches 70°C (158°F) or higher [A].
  8. 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.

  9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [C].
  10. 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.
  11. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
  12. Input the DTC: P0101.
  13. Check the DTC judgment result.

    Tester 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 INCOMPLETE or N/A, perform steps [B] through [C] again.

  14. 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. Freeze frame data records the engine condition when malfunctions are detected. 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.

(c) Turn the Techstream on.

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

(e) Read DTCs.

Result

Result

Proceed to

P0101 is output

A

P0101 and other DTCs are output

B

HINT:

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

B

GO TO DTC CHART

A

2.

CHECK INTAKE SYSTEM

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

OK:

No leak in air induction system.

HINT:

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

NG

REPAIR OR REPLACE INTAKE SYSTEM

OK

3.

CHECK PCV HOSE CONNECTIONS

(a) Check the PCV hose connections.

OK:

PCV hose is connected correctly and is not damaged.

NG

REPAIR OR REPLACE PCV HOSE

OK

4.

PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION)

(a) Connect the Techstream to the DLC3.

(b) Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

HINT:

  • When performing the Active Test, make sure the shift lever is in P or N.
  • The A/C switch and all accessory switches should be off.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.

(e) Confirm the Throttle Idle Position is ON and check the engine idling condition and MAP values in the Data List while performing the Active Test.

HINT:

  • Do not leave the EGR valve open for 10 seconds or more during the Active Test.
  • Be sure to return the EGR valve to step 0 when the Active Test is completed.

OK:

MAP and idling condition change in response to EGR step position as follows.

Standard:

-

EGR Step Position (Active Test)

0 Steps

0 to 30 Steps

Idling condition

Steady idling

Idling changes from steady to rough idling or engine stall

MAP

(Data List)

20 to 40 kPa (150 to 300 mmHg)

MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

OK

GO TO STEP 6

NG

5.

INSPECT EGR VALVE ASSEMBLY

(a) Remove the EGR valve assembly (See page ).

(b) Check if the EGR valve assembly is stuck open.

OK:

EGR valve is tightly closed.

HINT:

Perform "Inspection After Repairs" after replacing the EGR valve assembly (See page ).

NG

REPLACE EGR VALVE ASSEMBLY

OK

6.

REPLACE MASS AIR FLOW METER

(a) Replace the mass air flow meter (See page ).

HINT:

Perform "Inspection After Repairs" after replacing the mass air flow meter (See page ).

NEXT

7.

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch ON.

(c) Turn the Techstream on.

(d) Clear the DTC (See page ).

(e) Turn the ignition switch off and wait for 30 seconds.

(f) Turn the ignition switch ON and turn the Techstream on.

(g) Start the engine and warm it up.

(h) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

(i) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

(j) Input the DTC: P0101.

(k) 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's memory limit
NEXT

END

    Internal Control Module EEPROM Error (P062F)

    Mass Air Flow Circuit Low (P0102,P0103)

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