Excessive Exhaust Emissions/Odors

Symptom: Vehicle fails an emissions test or has an excessive "rotten egg" smell. Excessive odors do not necessarily indicate excessive emissions.

POSSIBLE CAUSE ACTION

IGNITION SYSTEM MALFUNCTION - Scope check Ignition System. Check SECONDARY CIRCUIT firing Kv and spark duration.
SEE IGNITION SYSTEM/OSCILLOSCOPE PATTERNS.

- Remove spark plugs and inspect for: cracks, excessive wear, improper gap, burned electrodes, and wet or heavy deposits. Replace as necessary.


- Inspect spark plug wires for proper plug wire routing, crossfire between spark plugs or wires shorting to ground.


- Check IGNITION TIMING for excessive spark advance or retard. SEE Powertrain Management/Ignition System/Specifications.

ENGINE MECHANICAL MALFUNCTION - Check COMPRESSION. Perform a compression check, and cylinder leakage test, look for sticking or leaking valves.

- Check for VACUUM LEAKS, inspect Intake manifold, gasket(s), and hoses.

- Check exhaust system for leaks, restriction, or damage.

- Check for fuel in crankcase.

EMISSIONS COMPONENT MALFUNCTION - Check EGR valve for binding or sticking in the open position.

- Check EGR Transducer for proper operation.

- Check for contaminated Catalytic Converter.

- Check EVAP Control system for proper operation.

FUEL SYSTEM MALFUNCTION - Check fuel pressure.

- Check for lean Air-Fuel mixture, (O2S Sensor output).

- Perform injector balance test.

- Check fuel quality.