Muffler Explosion (Rich Fuel Mixture)

Check idle speed and ensure ignition timing is correct.
Check airflow meter, coolant temperature sensor, throttle position sensor and air temperature sensor.
Check cold start injector and cold start injector time switch.
Ensure fuel system functions properly (pump, lines, filter and pressure regulator).
Check for fuel injector leakage.
Verify secondary ignition system performance.
Check engine compression and valve clearance.
Check throttle position sensor and injection signal circuit.
Check O2 sensor(s).
Check for exhaust system leaks.