Computed Timing Check

WARNING: This page is about a different car, the 1993 Mazda Navajo. However, it is still accessible from the selected car via links, so may be relevant.

Turn ignition off, and wait 10 seconds. Using jumper wire or test equipment, activate KOER SELF-TEST. Start engine, and check following:

If engine starts and stalls, or stalls during self-test, go to CIRCUIT TEST S.
If Code 998 is displayed, EEC-IV system is operating in Failure Mode Effects Management (FMEM). Vehicle cannot be diagnosed in KOER SELF-TEST. Rerun KOEO SELF-TEST.
Check computed timing after last service code has been displayed. Timing will remain fixed for 2 minutes after last code has been retrieved unless self-test is deactivated.
Computed timing at crankshaft should equal base timing (10 degrees BTDC) plus 20 degrees BTDC. This timing may vary 3 degrees. If computed timing is within specification, perform KOER SELF-TEST. If timing is not within specification, go to CIRCUIT TEST P, step 2).