Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1999EXPRESS 1 TON VAN V8-5.7L VIN RREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMIGNITION TIMINGADJUSTMENTS
1999 Chevrolet Express 1 Ton Van V8-5.7L VIN R
Ignition Timing: Adjustments
1999 Chevrolet Express 1 Ton Van V8-5.7L VIN RSECTION Adjustments
TEST PROCEDURE
The ignition timing cannot be adjusted. The distributor may need adjusting to prevent crossfire. To insure proper alignment of the distributor, perform the following:
1. With the ignition OFF, connect the scan tool.
2. Start the engine. Allow the engine to idle until the engine reaches normal operating temperature.
IMPORTANT: Cam Retard Offset reading will not be accurate below 1,000 RPM.
3. Increase engine speed to 1,000 RPM while performing the following steps.
4. Use the scan tool in order to monitor the Cam Retard Offset.
5. If the Cam Retard indicates a value of 0 degrees, the distributor is properly adjusted.
6. If the Cam Retard does not indicate 0 degrees, the distributor must be adjusted.
ADJUSTING PROCEDURE
1. With the engine OFF, slightly loosen the distributor hold down bolt.
IMPORTANT: Cam Retard Offset reading will not be accurate below 1,000 RPM.
2. Start the engine and raise the engine speed to 1,000 RPM.
3. Use the scan tool in order to monitor the Cam Retard Offset.
4. Rotate the distributor as follows:
^ To compensate for a negative reading, rotate the distributor in the counterclockwise direction.
^ To compensate for a positive reading, rotate the distributor in the clockwise direction.
5. Repeat step 4 until 0 degrees is obtained.
6. Turn OFF the ignition.
NOTE: Refer to Fastener Notice in Cautions and Notices.
7. Tighten the distributor hold-down bolt.
Tighten
Tighten the bolt to 3 N.m (25 lb ft).
8. Start the engine.
9. Raise the engine speed to 1,000 RPM and view the Camshaft Retard Offset.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.