INSPECTION & ADJUSTMENT

1987–88

1. Raise the hood and clean and mark the timing marks. Chalk or fluorescent paint makes a good, visible mark.
2. Disconnect the vacuum line to the distributor and plug the disconnected line. Disconnect the line at the vacuum source, not at the distributor.
3. Connect a timing light to the front (no.1) cylinder, a power source and ground. Follow the manufacturer's instructions.
4. Connect a tachometer to the engine.
5. Start the engine and reduce the idle to 700–750 rpm to be sure that the centrifugal advance mechanism is not working.
6. With the engine running, shine the timing light at the timing pointer and observe the position of the pointer in relation to the timing mark on the crankshaft pulley. All models have two notches on the pulley. Looking straight down on the marks, the one on the left is TDC, the one on the right is BTDC
7. If the timing is not as specified, adjust the timing by loosening the distributor holddown bolt and rotating the distributor in the proper direction. When the proper ignition timing is obtained, tighten the holddown bolt on the distributor.
8. Check the centrifugal advance mechanism by accelerating the engine to about 2,000 rpm. If the ignition timing advances, the mechanism is working properly.
9. Stop the engine and remove the timing light.
10. Reset the idle to specifications.
11. Remove the tachometer.

1989–93 Pickup and MPV

1. Run the engine to normal operating temperature.
2. Turn all electrical accessories OFF.
3. Disconnect the vacuum hoses from the vacuum control and plug it.
4. On fuel injected models, connect a jumper wire between the green, 1-pin test connector and ground.
5. Check the idle speed, and, if necessary, adjust it.
6. Mark the correct timing mark with white paint.
7. Connect a timing light according to the manufacturer's instructions.
8. With the engine running at idle, aim the timing light at the timing marks. If the correct timing is not indicated, loosen the distributor locknut and turn the distributor as needed to align the marks.
9. Tighten the locknut and recheck the timing.
10. Reconnect the vacuum hose and remove the jumper wire.

Navajo

With the EEC-IV EDIS systems, no ignition timing adjustment is possible (preset at the factory to 10°BTDC and is computer controlled) and none should be attempted.