With Scan Tool

WARNING: Apply parking brake and/or block wheels before performing any engine running test with the vehicle on the ground.

NOTE: To ensure correct base ignition timing distributor must be indexed correctly.

PURPOSE

Proper ignition timing is required to obtain optimum engine performance. A slipped timing belt can cause many driveablity problems. Check Timing belt alignment if a timing problem is suspected. SEE COMPUTERS AND CONTROL SYSTEMS/DIAGNOSIS, TESTING AND INSPECTION PROCEDURES.

PREPARATION

1. With engine OFF, place transmission in park or neutral and turn off all lights and accessories.
2. Connect scan tool [1] and timing unit:

- If using a magnetic timing probe, insert into receptacle in transmission bell housing, next to timing window. (Socket is for magnetic timing probe only.)

- If using a timing light, connect to number 1 spark plug cable. (Refer to timing light manufacturer's instructions for proper connection.)
CAUTION: Do not puncture cables or boots. Puncturing cables or boots can separate the conductor, resulting in high resistance. Puncturing the insulation also exposes the conductor, which can lead to corrosion or arcing to ground.

3. Start engine and allow to warm up to normal operating temperature.
4. Using scan tool [1], access basic timing mode. Malfunction Indicator Lamp (MIL), (previously called the Check Engine Lamp) and the radiator cooling fan should come on, and stay on throughout the procedure.)

Distributor Hold-Down:

Timing Scale -- Top, Front Of Bell Housing:

READING AND ADJUSTING TIMING

Check timing.

- If using magnetic probe, read timing unit.

- If using conventional timing light, point light at window in bellhousing.

2. Refer to Vehicle Emission Control Information (VECI) label under hood for correct timing specification. (If there is no VECI label, verify emission system and SEE SPECIFICATIONS.)

- If timing is within ±2° of specifications, do not adjust.

- If timing is not within ±2° of specifications, loosen distributor hold-down bolt just enough to allow distributor to be rotated. Rotate distributor until timing is within specification. Tighten distributor hold-down bolt, and recheck timing.

3. Using scan tool [1], erase Diagnostic Trouble Codes (DTC's) set during procedure.

Remarks:

[1] Follow scan tool manufacturer's instructions for procedures.