Inspection Procedure 14 - Engine Stalls When Decelerating
NOTE:
Possible causes are: defective idle air control motor system.
- Check if battery was previously disconnected. If battery was not disconnected, go to next step. If battery was disconnected, reconnect battery. Start and warm engine to normal operating temperature. Allow engine to idle for at least 10 minutes, and then recheck for trouble symptom.
- Using scan tool, check for stored Diagnostic Trouble Codes (DTCs). If stored DTCs exist, perform appropriate test procedures for each DTC, and clear DTCs from ECM. If no DTCs exist, go to next step.
- Perform scan tool service data inspection procedure on closed throttle position switch. See SCAN TOOL SERVICE DATA INSPECTION PROCEDURE.
- If closed throttle position switch operates correctly, go to next step. If closed throttle position switch does not operate correctly, check closed throttle position switch system. Perform DTC TEST NO. 25.
- Perform scan tool service data inspection procedure on throttle position sensor. See SCAN TOOL SERVICE DATA INSPECTION PROCEDURE.
- If throttle position sensor operates correctly, go to next step. If throttle position sensor does not operate correctly, check throttle position sensor circuit. Perform DTC TEST NO. 5.
- Using scan tool, perform scan tool service data inspection procedure on idle air control motor. If idle air control motor position does not drop to 0-2 steps when decelerating with engine RPM less than 1000 RPM, go to next step. If idle air control motor position drops to 0-2 steps when decelerating with engine RPM less than 1000 RPM, check for vehicle speed sensor malfunction. Perform DTC TEST NO. 23.
- Check for defective ignition coil, spark plugs and spark plug wires. Clean throttle body and check adjustment of fixed Speed Adjusting Screw (SAS). See the ADJUSTMENTS - TURBO article.