P1101
DTC P1101
DTC DESCRIPTOR
DTC P0101
Mass Air Flow (MAF) Sensor Performance
DTC P1101
Intake Air Flow System Performance
DIAGNOSTIC FAULT INFORMATION
Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection
TYPICAL SCAN TOOL DATA
MAF Sensor:
CIRCUIT DESCRIPTION
The intake flow rationality diagnostic provides the within-range rationality check for the mass air flow (MAF), the manifold absolute pressure (MAP), and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing 4 separate models for the intake system.
- The throttle model describes the flow through the throttle body, and is used to estimate the MAF through the throttle body as a function of barometric pressure (BARO), TP, intake air temperature (IAT), and estimated MAP.
- The first intake manifold model describes the intake manifold, and is used to estimate MAP as a function of the MAF into the manifold from the throttle body, and the MAF out of the manifold caused by engine pumping. The flow into the manifold from the throttle uses the MAF estimate calculated from the above throttle model.
- The second intake manifold model is identical to the first intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input.
- The fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model.
The estimates of MAF and MAP obtained from this system of models and calculations are then compared to the actual measured values from the MAF, the MAP, and the TP sensors and to each other to determine the appropriate DTC to fail. The table illustrates the possible failure combinations and the resulting DTC or DTCs.
CONDITIONS FOR RUNNING THE DTC
- DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0125, P0128, P0335, P0336, P0401, P0405, P1404 are not set.
- The engine speed is between 500-5,000 RPM.
- The IAT Sensor parameter is between -7 and +60°C (+19 and +140°F).
- The ECT Sensor parameter is between 70-121°C (158-250°F).
- This DTC runs continuously within the enabling conditions.
CONDITIONS FOR SETTING THE DTC
The engine control module (ECM) detects that the actual measured airflow from the MAF, the MAP, and the TP sensors is not within range of the calculated airflow that is derived from the system of models for more than 0.5 second.
ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.
CIRCUIT/SYSTEM VERIFICATION
IMPORTANT: If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
- Verify the integrity of the air induction system by inspecting for the following conditions:
- Any damaged components
- Loose or improper installation
- An air flow restriction
- An air flow leak
- Any vacuum leak
- Water intrusion
- Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust. Restricted Exhaust
- Road test the vehicle and verify that the MAF sensor calculated g/s and the actual MAF g/s parameters are near or equal to each other.
CAUTION: Refer to Road Test Caution.
- A skewed MAF sensor, intake air flow restriction or intake air flow leak after the MAF sensor may cause the calculated g/s and MAF g/s parameters to disagree. Road test the vehicle while observing both parameters under various engine loads.
- A wide open throttle (WOT) acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 3-8 g/s at idle to 190 g/s or more at the time of the 1-2 shift.
- A steady or intermittent high resistance of 25 ohms or more on the ignition 1 voltage circuit will cause the MAF sensor values to be skewed high by up to 30 g/s. Use the scan tool to compare the MAF Sensor parameter to a known good vehicle under various operating conditions.
- A skewed or stuck engine coolant temperature (ECT) or IAT sensor will cause the calculated models to be inaccurate and may cause this DTC to run when it should not. Refer to Temperature vs Resistance.
- The BARO that is used by the ECM to calculate the air flow models is initially based on the MAP sensor at ignition ON. When the engine is running, the ECM will continually update the BARO value near WOT using the MAP sensor and a calculation. A skewed MAP sensor will cause the BARO value to be inaccurate. Use the scan tool to compare the BARO parameter at ignition ON to the Altitude vs. Barometric Pressure table. Determine the altitude for your area and refer to Altitude vs Barometric Pressure.
- A skewed MAP sensor will also cause the first and second intake manifold models to disagree with the actual MAP sensor measurements. Use the scan tool to compare the MAP Sensor parameter to a known good vehicle under various operating conditions.
CIRCUIT/SYSTEM TESTING
1. With the ignition ON, the engine OFF, and the MAF sensor harness disconnected, connect a test lamp between the ignition 1 voltage circuit and a good ground. Measure the battery voltage and record the measurement. Measure for battery voltage between the ignition 1 voltage circuit at the test lamp probe end and a good ground.
- If the voltage is not within 1.5 volts of battery voltage, repair the high resistance in the circuit.
IMPORTANT: The test lamp is used to load the circuit. Use the J 35616-200 for this test. If the J 35616-200 is not available, use a test lamp that measures more than 20 ohms.
2. With a DMM, measure for a voltage range of 4.8-5.2 volts between the MAF sensor signal circuit and a good ground.
- If the voltage is less than 4.8 volts, test the circuit for a high resistance.
- If the voltage is within the specified range, test the circuit for a short to the IAT signal circuit or to any other 5-Volt reference circuit.
3. Turn OFF the ignition and all electrical accessories. Allow sufficient time for the control modules to power down before taking a resistance measurement.
4. Measure for a resistance of less than 5 ohms between the ground circuit of the MAF sensor and a good ground.
- If the resistance is more than 5 ohms, repair the high resistance in the ground circuit.
5. Connect the J 38522 to the vehicle.
6. Start the engine and observe the MAF Sensor parameter for a proper range of 4,950-5,025 Hz.
- If the MAF Sensor parameter is not within the specified range, replace the ECM.
- If the MAF Sensor parameter is within the specified range, replace the MAF sensor.
COMPONENT TESTING
To determine if the ECM can properly process the MAF sensor frequency signal, connect the J 38522 to the vehicle as follows:
1. Turn OFF the ignition.
2. Connect the battery voltage supply and ground the black lead.
3. Connect the red lead to the signal circuit of the MAF sensor.
4. Set the duty cycle switch to Normal.
5. Set the Frequency switch to 5 K.
6. Set the signal switch to 5 volts.
7. Start the engine.
8. Observe the MAF Sensor parameter for the correct range of 4,950-5,025 Hz.
REPAIR INSTRUCTIONS
IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Mass Air Flow (MAF)/Intake Air Temperature (IAT) Sensor Replacement
- Control Module References for ECM replacement, setup, and programming Verification Tests