P1101
DTC P1101
Circuit Description
Important: The following applies to the intake airflow system performance diagnostic that is used in this supercharged engine:
* When referring to the intake manifold models, the plenum volume between the throttle body and the supercharger is considered to be the intake manifold.
* When referring to engine pumping, the supercharger and the intercooler plenum are considered to be part of the engine.
* The manifold absolute pressure (MAP) sensor that resides in the engine intake manifold is used to adjust the engine airflow estimates to balance the airflow models.
The intake airflow system performance diagnostic provides the within-range rationality check for the mass air flow (MAF), supercharger inlet pressure (SCIP), 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), throttle position, intake air temperature (IAT), and estimated SCIP.
* The first intake manifold model describes the intake manifold and is used to estimate SCIP as a function of the MAF into the intake manifold from the throttle body and the MAF out of the intake manifold caused by engine pumping. The flow into the intake manifold from the throttle uses the MAF estimate calculated from the above throttle model.
* The second intake manifold model and 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.
* A fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model.
The estimates of MAF, SCIP, and TP that are obtained from this system of models and calculations are then compared to the actual measured values from the MAF, SCIP, and the TP sensors and to each other to determine the appropriate DTC to fail. The following table illustrates the possible failure combinations and the resulting DTC or DTCs.
If the powertrain control module (PCM) detects that the actual measured airflow from MAF, SCIP, and TP is not within range of the calculated airflow that is derived from the system of models, DTC P1101 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1101 Intake Air Flow System Performance
Conditions for Running the DTC
* DTCs P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0335, P0336, P1183, P1184, P2228, P2229 are not set.
* The engine speed is between 400-6,400 RPM.
* The IAT Sensor 1 parameter is between -7°C and +125°C (+19 and +257°F).
* The ECT Sensor parameter is between 70-125°C (158-257°F).
* This DTC runs continuously within the enabling conditions.
Conditions for Setting the DTC
The PCM detects that the actual measured airflow from the MAF, SCIP, and TP 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.
Diagnostic Aids
* Any condition that can cause the MAF, SCIP, and TP sensors to be shifted in value at the same time will cause this DTC to set.
* 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 3-6 g/s at idle to 180 g/s or more at the time of the 2-3 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
* A skewed or stuck engine coolant temperature (ECT) or IAT sensor 1 will cause the calculated models to be inaccurate and may cause this DTC to run when it should not.
* A skewed MAP sensor may cause this DTC to set.
* A steady or intermittent high resistance of 15 ohms or more on the ignition 1 voltage circuit will cause the MAF sensor values to be skewed high by up to 60 gs, and may cause this DTC to set. A high resistance will cause a driveability concern before this DTC sets.
* The BARO that is used by the PCM to calculate the airflow models is initially based on the BARO sensor at key ON. With the ignition ON and the engine OFF, the BARO Sensor parameter varies with the altitude. 101 kPa is the approximate value near sea level. This value will decrease by approximately 3 kPa for every 305 meters (1,000 feet) of altitude. Refer to Altitude Versus Barometric Pressure.
* If the condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections in Diagnostic Aids. Component Tests and General Diagnostics
Test Description
Step 1 - Step 6:
Step 7 - Step 12:
Step 13 - Step 18:
Step 19 - Step 26:
The numbers below refer to the step numbers on the diagnostic table.
5. This step will determine if any mechanical faults have caused this DTC to set.
6. The SC Inlet Pressure parameter is the difference between BARO and SCIP, and at KOEO should be close to zero.
14. This voltage drop test will determine if high resistance has caused this DTC to set.
16. This step verifies the voltage signal from the PCM to the MAF sensor connector.
17. This step will determine if the MAF sensor is able to generate a frequency signal.
18. This step will determine if an abnormal resistance or a short to the IAT signal circuit has skewed the MAF sensor frequency signal.