1988-95 MODELS
See Figures 6, 7, 8, 9, 10 and 11
This service procedure is for setting base ignition timing. Refer to underhood emission sticker for any additional service procedure steps and/or specifications.
These engines require a tachometer hook-up to the check connector-see illustrations. NEVER allow the tachometer terminal to become grounded; severe and expensive damage can occur to the coil and/or igniter.
Some tachometers are not compatible with this ignition system, confirm the compatibility of your unit before using.
- Warm the engine to normal operating temperature. Turn off all electrical accessories. Do not attempt to check timing specification or idle speed on a cold engine.
Fig. Fig. 6: Attach the tachometer to the battery and check connector terminals
- Connect a tachometer (connect the tachometer (+) terminal to the terminal IG- of the check connector) and check the engine idle speed to be sure it is within the specification given in the Tune-Up Specifications chart or underhood emission sticker.
- Remove the cap on the diagnostic check connector. Using a small jumper wire or Special Service Tool SST 09843-18020, short terminals TE1 (test terminal No. 1) and E1 (earth-ground) together.
- If the timing marks are difficult to see, shut the engine OFF and use a dab of paint or chalk to make them more visible.
- Connect a timing light according to the manufacturer's instructions.
Fig. Fig. 7: Early type of check connector and SST tool (jumper wire) for base timing adjustment
Fig. Fig. 8: Using the SST 09843-18020 or a jumper wire, connect terminals TE1 and E1 of the DLC1 (also used on OBD-II)
Fig. Fig. 9: Ignition timing marks 4A-GE engine-note the small notch on the pulley, this is the mark to align with the degree scale
Fig. Fig. 10: Timing marks 4A-FE and 7A-FE engines
- Start the engine and use the timing light to observe the timing marks. With the jumper wire in the check connector the timing should be to specifications (refer to underhood emission sticker as necessary) with the engine fully warmed up (at correct idle speed) and the transmission in correct position. If the timing is not correct, loosen the bolts at the distributor just enough so that the distributor can be turned. Turn the distributor to advance or ****** the timing as required. Once the proper marks are seen to align with the timing light, timing is correct.
Fig. Fig. 11: If necessary, loosen the 2 mounting bolts and turn the distributor to adjust the timing
- Without changing the position of the distributor, tighten the distributor bolts and double check the timing with the light (check idle speed as necessary).
- Disconnect the jumper wire or Special Service Tool (SST) at the diagnostic check connector.
This jumper will be used repeatedly during diagnostics in later sections. Take the time to make a proper jumper with correct terminals or probes. It's a valuable special tool for very low cost.
- Refer to the underhood emission sticker for timing specification and any additional service procedure steps. If necessary, repeat the timing adjustment procedure.
- Shut the engine OFF and disconnect all test equipment. Roadtest the vehicle for proper operation.
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