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 MANUALSPONTIAC1983GRAND PRIX BASE, 5.0 HREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMFUEL INJECTION SYSTEM - V6 & V8 DIESELADJUSTMENTINJECTION TIMINGCHECKING
1983 Pontiac Grand Prix Base, 5.0 H
Injection Timing: Checking
1983 Pontiac Grand Prix Base, 5.0 HSECTION Checking
- Place transmission selector in "P", apply parking brake and block drive wheels. Start engine and run at idle until fully warmed up. Shut off engine.NOTE: Failure to have engine fully warmed up will result in incorrect timing reading and adjustments.
- Remove air cleaner assembly and plug air crossover using Cover (J-26996-1 or equivalent). Disconnect EGR valve hose. Clean engine probe holder (RPM counter) and crankshaft balancer rim.
- Clean lens on both ends of glow plug probe and lens in photo-electric pick-up. Using a dulled toothpick, scrape carbon from combustion chamber side of glow plug probe. Retarded readings will result if probe is not clean.
- Install RPM probe into crankshaft RMP counter (probe holder). Remove glow plug from cylinder No. 1 on V6 models or No. 3 on V8 models. Install glow plug probe into glow plug opening and tighten to 8 ft. lbs. (11 N.m).
- Set timing meter offset selector to "A" (20) on V6 models or "B" (99.5) on V8 models. Connect meter leads to battery (Red to positive, Black to negative). Disconnect generator 2-lead connector. Start engine (transmission in "P") and adjust RPM to 1300 RPM on V6 engines and 1250 RPM on V8 engines.
- Observe timing readings at 2 minute intervals. When readings stabilize, compare to specification. On V6 engines, timing should be 6° ATDC @ 1300 RPM. On V8 engines, timing should be 4° ATDC @ 1250 RPM. Timing reading, when set to specification, will be negative (ATDC).
- Disconnect timing meter and install removed glow plug, tightening to 15 ft. lbs. (20 N.m) on V6 or 12 ft. lbs. (16 N.m) on V8. Connect generator 2-lead connector. Remove crossover cover and install air cleaner. Reconnect EGR valve hose.
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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.