Ignition Timing

Warm engine to normal operating temperature. Turn engine off, but keep ignition on for 5 seconds. Restart engine, and raise engine speed to 2000 RPM for 5 minutes. Return to idle. Ensure all accessories are off and idle speed is within specification. Adjust idle speed first if it is not within specification. See IDLE SPEED under IDLE SPEED & MIXTURE.
Connect timing light to No. 1 spark plug wire. Remove cap from duty check Data Link Connector (DLC), located near fusible link box, by battery. On TBI (Federal), connect a jumper wire between terminals "C" (Black wire) and "D" (Blue/Red wire) of duty check DLC. See Fig 2 . On MFI (Calif. and New York), connect a jumper wire between terminals No. 4 (Black wire) and No. 5 (Blue/Red wire) of duty check DLC. See Fig 2 .
On all models, check timing mark alignment on crankshaft pulley with timing marks on timing belt cover. Ignition timing must be within specification. See IGNITION TIMING SPECIFICATIONS .
If ignition timing is not as specified, loosen distributor hold-down flange bolts, and rotate distributor to obtain correct ignition timing. Tighten distributor hold-down flange bolts to 15 ft. lbs. (20 N.m). Recheck ignition timing.
Turn engine off. Remove jumper wire and install cap on duty check DLC. Remove test equipment.

Fig 1: Duty Check DLC Terminal ID (TBI Federal)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Duty Check DLC Terminal ID (MFI Calif. & New York)

Courtesy of GENERAL MOTORS CORP.

IGNITION TIMING SPECIFICATIONS

Application

Man. Trans.

Auto. Trans.

TBI (Federal)

⁽²⁾ 8 @ 800

MFI (Calif. & New York)

⁽³⁾ 5 @ 800

⁽¹⁾	If specification differs from emission label, use specification listed on emission label.

⁽²⁾	With jumper wire installed between terminals "C" (Black wire) and "D" (Blue/Red wire) of duty check data link connector, located near front of battery tray.

⁽³⁾	With jumper wire installed between terminals No. 4 (Black wire) and No. 5 (Blue/Red wire) of duty check data link connector, located near front of battery tray.