Engine Mechanical
- Excessive oil in combustion chamber. Leaking valve seals.
- Low cylinder compression. Check the compression. See MECHANICAL INSPECTION in BASIC DIAGNOSTIC PROCEDURES - 3.1L CENTURY, GRAND PRIX & MALIBU article.
- Check for incorrect engine parts, such as cylinder heads, camshaft and valve train components, pistons, etc.
- Diagnose mechanical condition of the engine. See appropriate article in ENGINES.