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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1366 (ENGINE CONTROLS AND FUEL - 4.4L - DTC P0010 TO DTC P0158)DTC P0106CIRCUIT DESCRIPTION
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Circuit Description

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit Description
WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: The following applies to the intake airflow system performance diagnostic that is used in this supercharged engine:
  • When referring to the supercharger 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) estimates are used in the engine air flow estimates. Air flow into the intake system must be the same as the air flow out of the intake system, the Intake Airflow Rationality Diagnostics (IFRD) calculates air flowing out of the engine based on MAP estimates, volumetric efficiency, and RPM.

The intake airflow system performance diagnostic provides the within-range rationality check for the mass air flow (MAF), supercharger inlet absolute pressure (SCIAP), MAP, by-pass valve stuck, 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 SCIAP. The information from this model is displayed on the scan tool as the MAF Performance Test parameter.
  • The first supercharger intake manifold model describes the pressure at the supercharger intake manifold and is used to estimate SCIAP 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 supercharger intake manifold from the throttle uses the MAF estimate calculated from the above throttle model. The information from this model is displayed on the scan tool as the MAP Performance Test 1 parameter.
  • The second supercharger intake manifold model is identical to the first supercharger intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input. The information from this model is displayed on the scan tool as the MAP Performance Test 2 parameter.
  • A fourth model is created from the combination and additional calculations of the throttle model and the first supercharger intake manifold model. The information from this model is displayed on the scan tool as the TP Performance Test parameter.
  • In addition 5 new models have been added, these models run in the background.

The estimates of MAF, SCIAP, and TP that are obtained from this system of models and calculations are then compared to the actual measured values from the MAF, SCIAP, 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.

Scan Tool Diagnostic Test Results

MAF Performance Test MAP Performance Test 1 MAP Performance Test 2 TP Performance Test DTCs Passed DTCs Failed
- - OK OK P0101, P0121, P012B, P1101 None
OK OK Fault OK P0101, P0121, P012B, P1101 None
Fault OK Fault OK P0121, P012B, P1101 P0101
OK Fault Fault OK P0101, P0121 P012B
Fault Fault Fault OK P0121, P1101 P0101
P012B
- - OK Fault P0101, P012B, P1101 P0121
OK OK Fault Fault P0101, P0121, P012B, P1101 None
Fault OK Fault Fault P0101, P0121, P012B, P1101 P0101, P1101
- Fault Fault Fault P0101, P0121, P012B P0101, P1101
RENDER: 1.0x

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
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  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.