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Throttle/Idle Learn

Description

The engine control module (ECM) learns the airflow through the throttle body to ensure the correct tick-over. 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 tick-over may be unstable or a DTC may set if the learnt values do not match the actual airflow.

Conditions for Running the Idle Learn Procedure

With Scan Tool - Reset Procedure

    • DTCs  P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0128, P0171, P0172, P0201, P0202, P0203, P0204, P0222, P0223, P0300, P0351, P0352, P0353, P0354, P0496, P0601, P0604, P0606, P0641, P0651, P0697, P06A3, P1516, P2101, P2119, P2122, P2123, P2127, P2128, P2135, P2138, or P2176 are not set.
    • Ignition ON, engine OFF.
    • The vehicle speed sensor (VSS) is 0 km/h (0 MPH).

Without Scan Tool - Learn Procedure

    • DTCs  P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0128, P0171, P0172, P0201, P0202, P0203, P0204, P0222, P0223, P0300, P0351, P0352, P0353, P0354, P0496, P0601, P0604, P0606, P0641, P0651, P0697, P06A3, P1516, P2101, P2119, P2122, P2123, P2127, P2128, P2135, P2138, or P2176 are not set.
    • The engine speed is between 450-4 000 RPM.
    • The engine vacuum is greater than 5 kPa.
    • The mass air flow (MAF) is greater than 2 g/s.
    • The ignition 1 voltage is greater than 10 V.

Idle Learn Procedure

With Scan Tool - Reset Procedure

  1. Ignition ON, engine OFF, with a scan tool, perform the Idle Learn Reset in Module Setup.
  2. Start the engine, monitor the Throttle Body Idle Airflow Compensation parameter. The Throttle Body Idle Airflow Compensation value should equal 0% and the engine should be ticking over at a normal tick-over speed.
  3. Clear the DTCs with a scan tool.

Without Scan Tool - Learn Procedure

    Note: Do NOT perform this procedure if DTCs are set.

  1. Start and allow the engine to tick over in park/neutral for 3 min.
  2. With a scan tool, monitor the desired and the actual engine speed.
  3. The ECM will start to learn the new tick-over cells and the desired engine speed should start to decrease.
  4. Ignition OFF for 60 s.
  5. Start and allow the engine to tick over in park/neutral for 3 min.
  6. After the 3 min running time the engine should be ticking over normally.

    7. Note: 

       • During the drive cycle the malfunction indicator lamp (MIL) may illuminate and tick-over speed DTCs set. If tick-over speed DTCs set, clear the DTCs so the ECM can continue to learn.
       • If the vehicle is driven for more than 10 km (6 mi) a Barometric Pressure (BARO) update is necessary so the ECM can continue to learn. To update the BARO, accelerate to wide open throttle (WOT) and then release the throttle.

    ⇒If the engine tick-over speed has not been learned, the vehicle will need to be driven at speeds above 70 km/h (44 MPH) with several decelerations and extended tick-over periods.
  7. After the drive cycle, the engine should be ticking over normally.
    8. ⇒If the engine tick-over speed has not been learned, turn OFF the ignition for 60 s and repeat step 6.
  8. Once the engine speed has returned to normal, clear the DTCs with a scan tool.
   


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