When the engine operates beyond the controlled limits, check for the following, as necessary:
Faulty ignition electrical system components.
The ignition timing may be too far advanced.
Inoperative Exhaust Gas Recirculation (EGR) valve.
Inoperative Positive Crankcase Ventilation (PCV) valve.
Faulty or loose spark plugs.
Clogged fuel delivery system.
Sticking, leaking or broken valves.
Excessive deposits in the combustion chambers.
Leaks in the vacuum system.
Fault with the computerized engine control system.