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 MANUALSPONTIAC1991FIREBIRD V8-350 5.7LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMIGNITION TIMINGADJUSTMENTS
1991 Pontiac Firebird V8-350 5.7L
Ignition Timing: Adjustments
1991 Pontiac Firebird V8-350 5.7LSECTION Adjustments
EST By-Pass Connector:
The ignition timing marks are located on the engine front cover. A saw slot on the balancer indicates No. 1 piston position.
PROCEDURE:
1. With the engine running at normal operating temperature, turn OFF all accessories and disconnect the EST By-Pass connector located at the harness near the firewall.
^ An ECM code will be set when the EST By-Pass connector is disconnected.
2. Use a timing light and tachometer to set the timing at the specified RPM by loosening the distributor clamp bolt and rotating the distributor until the specified timing is obtained.
^ Base Timing 6° BTDC at 600 RPM
3. Tighten the distributor clamp bolt and recheck the timing to make sure the distributor was not moved when the clamp was tightened.
4. Turn the engine OFF and connect the EST By-Pass connector.
5. Clear the ECM Code by disconnecting the negative battery cable for at least 30 seconds.
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.