Preliminary Checks

Check for intake air leaks. Check ignition timing. See BASIC TESTING article in the ENGINE PERFORMANCE Section.

• Check EGR operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
• Check EGR control solenoid valve. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
• Check vacuum hoses for leakage or misrouting. See VACUUM DIAGRAMS article in the ENGINE PERFORMANCE Section.
• Check spark plugs for evidence of excessive oil consumption.