Toyota RAV4 manuals

Toyota RAV4 Service Manual: Mass air flow circuit range / performance problem

Toyota RAV4 Service Manual / 2Az-fe engine mechanical / Sfi system / Diagnostic trouble code chart / Mass air flow circuit range / performance problem

Toyota RAV4. Mass air flow circuit range / performance problem


Description

Refer to dtc p0100 (see page es-86).

Toyota RAV4. Mass air flow circuit range / performance problem


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 these components of the maf 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 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 set.

Monitor strategy

Toyota RAV4. Monitor strategy


Typical enabling conditions

Toyota RAV4. Typical enabling conditions


Toyota RAV4. Typical enabling conditions


Typical malfunction thresholds

Toyota RAV4. Typical malfunction thresholds


Wiring diagram

Refer to dtc p0100 (see page es-88).

Confirmation driving pattern

Hint:

Performing this confirmation pattern will activate the mass air flow performance monitor.

Toyota RAV4. Confirmation driving pattern


  1. Connect the intelligent tester to the dlc3.
  2. Turn the ignition switch on.
  3. Turn the tester on.
  4. Clear dtcs (see page es-35).
  5. Start the engine, and warm it up until the engine coolant temperature reaches 70c (158f) or higher.
  6. Drive the vehicle at approximately 100 km/h (62 mph) for 20 seconds or more.
  7. On the tester, select the following menu items: diagnosis / enhanced obd ii / dtc info / pending codes and check if any dtcs (any pending dtcs) are set.

Inspection procedure

Hint:

Read freeze frame data using the intelligent tester. 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.

  1. Check any other dtcs output (in addition to dtc p0101)

  1. Connect the intelligent tester to the dlc3.
  2. Turn the ignition switch on.
  3. Turn the tester on.
  4. Select the following menu items: diagnosis / enhanced obd ii / dtc info / current codes.
  5. Read dtcs.

Toyota RAV4. Check any other dtcs output (in addition to dtc p0101)


Hint:

If any dtcs other than p0101 are output, troubleshoot those dtcs first.



  1. Check air induction system

  1. Check the air induction system for vacuum leakage.

Ok:

No leakage from air induction system.



  1. Check pcv hose connections

Ok:

Pcv hose is connected correctly and is not damaged.



Replace mass air flow meter

Mass or volume air flow circuit
Description The mass air flow (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 ...

Intake air temperature circuit malfunction
Description The intake air temperature (iat) sensor, mounted on the mass air flow (maf) meter, monitors the iat. The iat sensor has a built-in thermistor with a resistance that varies ac ...

Other materials:

Inspection
Inspect generator brush holder assembly Using a vernier caliper, measure the brush length. Standard length: 9.5 To 11.5 Mm (0.374 To 0.453 In.) Minimum length: 4.5 Mm (0.177 In.) If the brush length is less than the minimum, replace the generator brush holder assembly. Inspe ...

Removal
Discharge fuel system pressure (see page fu-9) Disconnect cable from negative battery terminal Caution: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to prevent airbag and seat belt pretensioner activation. Remove radiator support op ...

Disassembly
Remove park/neutral position switch assembly Remove the nut, washer and control shaft lever. Using a screwdriver, pry off the lock plate. Remove the nut and lock plate. Remove the 2 bolts and pull out the switch. Remove breather plug hose Remove oil coo ...

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