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 distributor cap, rotor and spark plug wires for proper plug wire routing, crossfire between spark plugs (in cap) or wires, wires shorting to ground and rotor shorting to ground via distributor shaft.


- 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.