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Throttle/Idle Learn

Description

The engine control module (ECM) learns the airflow through the throttle body to ensure the correct engine speed. The learnt airflow values are stored within the ECM. These values are learned to adjust for production variation and will continuously learn during the life of the vehicle to compensate for reduced airflow due to throttle body coking. Anytime the throttle body airflow rate changes, for example due to cleaning or replacement, the values must be re-learned.

An engine that had a heavily coked throttle body that has been cleaned or replaced may take several drive cycles to learn out the coking. To accelerate the process, the scan tool has the ability to reset all learnt values back to zero. A new ECM will also have values set to zero.

The engine speed may be unstable or a DTC may set if the learned values do not match the actual airflow.

Conditions for Running the Throttle Learn Procedure

Reset Procedure

    • DTCs  P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0121, P0122, P0123, P0128, P0171, P0172, P0201, P0202, P0203, P0204, P0222, P0223, P0300, P0351, P0352, P0353, P0354, P0601, P0604, P0606, P060D, P0641, P0651, P0697, P06A3, P1101, P1516, P2101, P2119, P2122, P2123, P2127, P2128, P2135, P2138, or P2176 are not set.
    • Vehicle in Service Mode.
    • The vehicle speed sensor (VSS) is 0 km/h (0 MPH).

Learn Procedure

    • DTCs  P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0121, P0122, P0123, P0128, P0171, P0172, P0201, P0202, P0203, P0204, P0222, P0223, P0300, P0351, P0352, P0353, P0354, P0601, P0604, P0606, P060D, P0641, P0651, P0697, P06A3, P1101, P1516, P2101, P2119, P2122, P2123, P2127, P2128, P2135, P2138, or P2176 are not set.
    • The engine speed is between 1,400-4,000 RPM.
    • The manifold absolute pressure (MAP) is greater than 5 kPa.
    • The mass air flow (MAF) is greater than 2 g/s.
    • The ignition voltage is greater than 10 V.

Throttle Learn

Reset Procedure - Performed after the throttle body is cleaned or replaced

  1. Vehicle in Service Mode, perform the Idle Learn Reset with a scan tool.
  2. Engine running, monitor the TB Idle Airflow Compensation parameter with a scan tool. The TB Idle Airflow Compensation value should equal 0 %.
  3. Clear the DTCs and return to the diagnostic that referred you here.

Learn Procedure - Performed after the ECM is programmed or replaced

    Note: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

  1. Engine running for 3 minutes.
  2. Monitor the Engine Speed with a scan tool.
  3. The ECM will start to learn the new idle cells and the Engine Speed should start to decrease.
  4. Vehicle OFF for 60 s.
  5. Engine running for 3 minutes.
  6. After the 3 minute run time the engine speed should be normal.
  7. Once the engine speed has returned to normal, clear DTCs and return to the diagnostic that referred you here.
   


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