Backfires

DEFINITION:
Fuel ignites in intake manifold, or in exhaust system, making a loud popping noise.

Check Powertrain System, if not already completed

Check Ignition System, looking in particular for:

- Spark Plug Wires
- Crossfire Between Cylinders
- Wrong Firing Order

Check Fuel System, looking in particular for:

- Fuel Quality
- Low Octane Level
- Contaminants

- Low Fuel Pressure

- Low Flow Rate Injector

Check Exhaust, looking in particular for:

- Restricted Catalytic Converter or Exhaust

Check for the following mechanical causes:

- Valves Sticking in Guides

- Worn Camshaft Lobes

- Broken/Weak Valve Springs

- Camshaft Timing