Computed Timing Check
Connect timing light and check ignition timing. See IGNITION TIMING in ADJUSTMENTS article in this section. Perform the following procedure as applicable:
- If ignition timing is not correct, refer to the appropriate circuit test. See the following menu:
- For 2.3L, see: CIRCUIT TEST PB .
- For 3.0L, see: CIRCUIT TEST PA .
- For 4.0L, see: CIRCUIT TEST PC .
- If engine starts and then stalls, go to CIRCUIT TEST S .
- If engine will not start, refer to the appropriate circuit test. See the following menu:
- For 2.3L, see: CIRCUIT TEST AB .
- For 3.0L, see: CIRCUIT TEST AA .
- For 4.0L, see: CIRCUIT TEST AC .
DO NOT enter this test sequence until a Code 11 or 111 (pass code) has been retrieved in KOEO SELF-TEST. If system has not passed KOEO SELF-TEST, codes received from KOER SELF-TEST may not be valid.
Deactivate self-test by removing and reconnecting jumper wire or by procedure specified by manufacturer of test equipment in use. Start engine, and run it for 2 minutes at 2000 RPM to warm Heated Oxygen Sensor (HO2S). Turn engine off, and wait 10 seconds. Activate KOER SELF-TEST using a jumper wire or appropriate procedure for test equipment used. Start engine. Record all service codes displayed.
Check following items:
- If Code 98 or 998 is displayed, EEC-IV system is operating in Failure Management Effects Mode (FMEM). PCM has detected an out-of-range sensor and has substituted a fixed value to enable vehicle to continue operation.
- If vehicle is equipped with a Brake On-Off (BOO) switch, brake pedal must be depressed and released after ID code portion of test.
- On vehicles with Power Steering Pressure (PSP) Switch, turn steering wheel at least 1/2 turn and release within 1-2 seconds after ID code portion of test.
- On vehicles with Transmission Control Switch (TCS), cycle TCS switch after vehicle ID code is given.
- If Dynamic Response Code appears, perform a brief Wide Open Throttle (WOT). DO NOT perform WOT unless requested.
- If a Code 11 or 111 (pass code) is retrieved during KOER SELF-TEST, service Continuous Memory Codes retrieved in KOEO SELF-TEST. See SERVICE CODE REFERENCE CHARTS.
- If a Code 11 or 111 (pass code) is retrieved during Continuous Memory Code portion of KOEO SELF-TEST and no driveability problem exists, EEC-IV testing is complete. If driveability problems are still present, proceed to the TESTS W/O CODES article in this section.
- If KOER codes are present, see SERVICE CODE REFERENCE CHARTS . If system will not output codes, go to CIRCUIT TEST QA .