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 MANUALSCHRYSLER1987FIFTH AVENUE 5.2 4REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMEFC SYSTEMTESTINGWARM DRIVEABILITY TEST 11 - IGNITION TIMING SYSTEM CHECK
1987 Chrysler Fifth Avenue 5.2 4
Warm DRIVEABILITY Test 11 - Ignition Timing System Check
1987 Chrysler Fifth Avenue 5.2 4SECTION Warm DRIVEABILITY Test 11 - Ignition Timing System Check
- Connect a tachometer and timing light. Ground the carburetor switch. Start the engine. Raise engine speed to more than 1100 RPM until engine reaches normal operating temperature. On 2-Bbl. models, disconnect and plug the vacuum hose to the computer.
- Engine speed should be 450-650 RPM on 2-Bbl. models and 550-750 RPM on 4-Bbl. models. Adjust idle speed as necessary. Basic timing should be within 2° of specifications. See BASIC TIMING SPECIFICATIONS
chart. Adjust timing as necessary.BASIC TIMING SPECIFICATIONS
Application Computer No. Specification Fed. 2-Bbl. 4289813 7 Calif. 2-Bbl. 4289913 7 Fed. & Calif. 4-Bbl. 4289919 16 " 4289921 16 - If basic timing is okay, remove jumper lead from carburetor ground switch. On 4-Bbl. models, disconnect and plug vacuum hose to the computer. Connect a vacuum pump to the computer and apply 16 in. Hg vacuum. Raise engine speed to more than 2000 RPM. Timing should be within 4° of specifications. See SPARK ADVANCE SPECIFICATIONS
chart.SPARK ADVANCE SPECIFICATIONS (1)
Application Computer No. Spark Advance Fed. 2-Bbl. 4289813 46 Calif. 2-Bbl. 4289913 46 Fed. & Calif. 4-Bbl. 4289919 & 4289921 38 (1) Specifications are plus or minus 4°. - If spark advance is not within specifications, replace the computer. If spark advance is okay, apply 16 in. Hg vacuum (2-Bbl. models) and 2 in. Hg vacuum (4-Bbl. models) to the computer. Position fast idle speed screw on the 2nd highest step of the fast idle cam. Tap lightly on the intake manifold near the detonation sensor while watching the timing. Timing should retard as you tap on the intake manifold.NOTE: The amount of timing retard is directly proportional to the frequency of the tapping. Maximum retard is 16°.
- If timing does not retard, check the wiring between the detonation sensor and the computer for open or short circuits. If wiring is okay, replace the detonation sensor and repeat step 4). If timing still does not retard, replace the computer.
- If timing retards, return engine to idle speed. Unplug vacuum supply hose to the computer and connect a vacuum gauge to it. Vacuum reading should be manifold vacuum. If vacuum reading is not as specified, check and repair vacuum supply from carburetor. If vacuum reading is okay, proceed to WARM DRIVEABILITY TEST 12 .
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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.