Test No 12 - Basic Engine Test

If the results of diagnostic tests 1 through 6 indicate that the CEC system is functioning normally and engine performance remains inadequate, perform the following test. Determine which direction, rich or lean, that stepper motor metering pins consistently move toward.

1. If direction of movement is toward rich, inspect for air leaks at intake manifold and carburetor gaskets. Inspect for faulty vacuum hoses at fittings. Repair source of air leaks and retest. Check for exhaust leaks at or near oxygen sensor. Repair and retest.
2. If metering pins vary consistently within midrange, operation is normal, and test is complete.
3. If direction of movement is lean, check for faulty spark plug(s), misadjusted ignition timing and malfunctioning ignition advance mechanisms. Adjust or replace components as necessary. Retest.
4. If timing, advance and spark plugs do not test okay, adjust and/or replace as necessary. If they do test okay, check carburetor idle speed adjustment and choke adjustment. Check operation of choke linkage. Ensure hoses and wires are not interfering with or restricting carburetor linkage. Repair as necessary and retest.
5. Inspect heated air tube for proper connection at air cleaner and exhaust manifold heat stove. Repair as necessary and retest. Inspect EGR valve for correct installation and proper operation. Repair as necessary and retest. Inspect PCV valve for proper operation. Repair as necessary and retest. Inspect vapor canister for proper "purge" operation and condition of hoses. Repair as necessary and retest.