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HOMESERVICE MANUALSCHEVROLET2006CHEVY EXPRESS G2500, VAN CARGO, 6.6 2REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 5 (ENGINE CONTROL SYSTEM - 4.3L - TROUBLESHOOTING & DIAGNOSIS)BACKFIRE
2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2

Section 5 (Engine Control System - 4.3L - Troubleshooting & Diagnosis): Backfire

2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2SECTION Backfire
WARNING: This page is about a different variant/trim than selected.
Backfire

Inspections Actions
DEFINITION: Fuel ignites in the intake manifold or in the exhaust system, making a loud popping noise.
Preliminary Inspections
Fuel System
Sensor/System
Ignition System
  • In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures:
  • Remove spark plugs and inspect for the following:
    • Correct heat range
    • Wet plugs
    • Cracks
    • Wear
    • Improper gap
    • Burned electrodes
    • Heavy deposits
    • Verify that the spark plugs are of the correct type.
    • Inspect for proper ignition voltage output with J 26792  HEI Spark Tester. See Special Tools .
  • An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gage gap tool.
  • If the spark plugs are found to be fouled, determine the cause before replacing the spark plugs.
  • Inspect for damaged or misaligned spark plug boots.
  • Inspect the electronic ignition (EI) module for a proper ground connection.
  • Monitor the Misfire Current Counters while driving the vehicle in the conditions that the symptom occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300 .
  • Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply the water.
Engine Cooling System
  • Inspect the engine coolant level for being low. Refer to Loss of Coolant in Engine Cooling.
  • Inspect the engine thermostat for proper operation and for the correct heat range. Refer to Thermostat Diagnosis in Engine Cooling.
Engine Mechanical
Additional Inspections
  • Visually and physically inspect the vacuum hoses for splits, kinks, and proper connections and routing as shown on the Vehicle Emission Control Information label.
  • Inspect the intake manifold and the exhaust manifold passages for casting flash.
  • Inspect the exhaust system for possible restrictions. Inspect the following:
    • Inspect the exhaust system for damaged or collapsed pipes.
    • Inspect the mufflers for heat distress or possible internal failure.
    • Inspect for possible plugged catalytic converter. Refer to Restricted Exhaust in Engine Exhaust.
  • Electromagnetic interference (EMI) circuit can cause an engine misfire condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM parameter with little change in actual engine RPM change may indicate that EMI is present. If a problem exists, inspect for high voltage components near the ignition control circuits.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.