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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.
• | DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0122, P0123, P0128, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0222, P0223, P0300, P0351, P0352, P0353, P0496, P0601, P0604, P0606, P060D, P0641, P0651, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, or P2176 are not set. |
• | Ignition ON, engine OFF. |
• | The vehicle speed sensor (VSS) is 0 km/h (0 MPH). |
• | DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0122, P0123, P0128, P0171, P0172, P0174, P0175, P0201, P0202, P0203, P0204, P0205, P0206, P0220, P0222, P0223, P0300, P0351, P0352, P0353, P0496, P0601, P0604, P0606, P060D, P0641, P0651, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, or P2176 are not set. |
• | The engine speed is between 450-4,000 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 volts. |
Note: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
Note: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.
⇒ | 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. |
⇒ | If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds and repeat step 6. |
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