Ignition Timing & Idle Set RPM Adjustment Procedure

IGNITION TIMING PROCEDURE

To obtain optimum engine performance, the distributor must be correctly positioned on the engine to give proper ignition timing.

Test procedures are as follows:

(1) Connect a suitable Power Timing Light to number one cylinder (refer to the equipment manufacturer's instructions for correct connecting procedures) or a suitable magnetic timing unit (use a negative 10~ offset when required).

NOTE: 1.6L number one cylinder is the one next to the transaxle housing.

Do not puncture cables, boots or nipples with test probes. Always use proper adapters. Puncturing the spark plug cable with a probe will damage the cables. The probe can separate the conductor and cause high resistance. In addition breaking the rubber insulation may permit secondary current to arc to ground.

(2) Connect red lead of the test tachometer unit to the negative primary terminal of the coil and the black lead to a good ground.

(3) Turn selector switch to the appropriate cylinder position.

(4) Start engine and run until operating temperature is obtained or if at temperature, wait two minutes for engine to stabilize.

(5) With engine at normal operating temperature (off fast idle), momentarily open the throttle above 1100 rpm and release to make sure there is no bind in the linkage and that idle speed screw is against its stop.

(6) Connect a jumper wire between the carburetor switch and ground. Disconnect and plug the vacuum hose at the Computer.

NOTE: Engine rpm will drop when vacuum hose is removed from computer.

(7) Read engine rpm on 1000 rpm scale. If the engine rpm is at or below the curb idle specified on the label, proceed to the next step. If it is higher, turn the idle speed screw until engine rpm is at curb idle specified on label.

(8) Aim Power Timing Lamp at timing hole in bell housing 2.2L, crankcase cover 1.6L or read magnetic timing unit. If flash occurs when timing mark is before specified degree mark, timing is advanced. To adjust, turn distributor housing in direction of rotor rotation.
If flash occurs when timing mark is after specified degree mark, timing is retarded. To adjust, turn distributor housing against direction of rotor rotation.

If timing is within +/- 2~ of value specified on the label, proceed to step (10). If outside specified tolerance proceed to step (9).

(9) Loosen distributor hold-down arm screw just enough so the distributor housing can be rotated in its mounting. Turn distributor housing until specified label value is reached. Tighten the hold-down arm screw and recheck timing. Remove timing device and jumper wire from carburetor switch. Reset engine idle speed, following the "Idle Set rpm Adjustment Procedure".

(10) Turn engine off. Remove timing device and jumper wire from carburetor switch. If engine rpm was lowered to check timing reset engine idle speed following the "Idle Set rpm Adjustment Procedure".

IDLE SET RPM ADJUSTMENT PROCEDURE

NOTE: This procedure should only be performed if the basic ignition timing had to be adjusted to specifications, or engine idle speed had to be lowered to check and/or adjust basic ignition timing.

(1) Where applicable disconnect the O2 system test connector.

(2) Connect a tachometer to the engine and ground the carburetor switch with a jumper wire.

(3) Unplug the connector at the radiator fan and install a jumper wire so that the fan will run continuously.

(4) Remove the PCV valve and allow it to draw underhood air.

(5) Disconnect and plug the vacuum hose connector at the EGR CVSCC valve.

(6) Start the engine.

(7) Allow the engine speed to stabilize for two minutes at operating temperature.

(8) Turn idle speed adjusting screw until tachometer indicates correct rpm as shown on the emission label.

(9) Reinstall CVSCC vacuum connector and PCV valve.