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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 Lucerne 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Backfire

Inspection/Test

Action

DEFINITION: Ignition occurs in the intake manifold, or in the exhaust system, making a loud popping noise.

Preliminary
    • Refer to Important Preliminary Checks Before Starting in Symptoms - Engine Controls .
    • Search for bulletins.

Sensor/System
    • Inspect the mass air flow (MAF) sensor for proper installation, obstruction, contamination, and damage. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement .
    • Inspect the MAF sensor for proper seating of the connector and terminal.
    • Test the manifold absolute pressure (MAP) sensor for proper installation, obstruction, and damage. Refer to Manifold Absolute Pressure Sensor Replacement .
    • Ensure the quality of the MAP sensor vacuum source.
    • Monitor the knock sensor (KS) system for excessive spark retard activity.

Fuel System
    •  Test the fuel system for correct operation, restriction, volume, and pressure. Refer to Fuel System Diagnosis .
    • Test for proper operation of the fuel injectors. Refer to Fuel Injector Diagnosis .
    • Test for fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect the throttle body for coking. Refer to Throttle Body Inspection and Cleaning .
    • Inspect for lean or rich conditions. Refer to DTC P0171, P0172, P0174 or P0175 Conditions for Running the DTC. Refer to DTC P0171 or P0172 or DTC P0174 or P0175 .

Ignition System
    • Inspect for proper ignition system operation. Refer to Electronic Ignition (EI) System Diagnosis .
    • Inspect the spark plugs. Refer to Spark Plug Inspection .
    • Inspect the spark plugs for correct application. Refer to Ignition System Specifications .
    • Inspect for damaged ignition coils within the ignition coil module assemblies.
    • Inspect for damaged or misaligned spark plug boots.

Engine Mechanical
    • Inspect the following conditions:
       - Cylinder compression--Refer to Engine Compression Test .
       - Sticking or leaking valve
       - Worn camshaft lobes
       - Valve timing
       - Worn rocker arms--Refer to Valve Rocker Arm Cleaning and Inspection .
       - Broken valve springs--Refer to Valve Spring Inspection and Measurement .
       - Excessive oil in the combustion chamber-leaking valve seals
    • Inspect for incorrect basic engine parts. Inspect the following:
       - Camshaft
       - Cylinder heads
       - Pistons, etc.

Additional Inspections
    • Inspect the secondary air injection (AIR) check valves for proper operation.
    • Inspect for proper operation of the torque converter clutch (TCC). Refer to Torque Converter Diagnosis .
    • Inspect the intake and exhaust system for casting flash.
    • Inspect the exhaust system for possible leaks and/or restrictions. Refer to Symptoms - Engine Exhaust .