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.
1990 Jeep Cherokee Laredo, 2D Utility, AutomaticFACTORY OEM SERVICE PROCEDURE
4.2L 6-Cylinder
- Set parking brake. Shift automatic transmission to Park or manual transmission to Neutral. With A/C off, start engine and attain normal operating temperature.
- With ignition OFF, connect an ignition timing light and a calibrated, expanded-scale tachometer.NOTE: If timing light has an adjustable advance control feature, turn control to OFF position.
- Disconnect 4 " and 10 " Hg (CEC System) vacuum switch assembly wire connector (located at top of valve cover). Disconnect and plug distributor vacuum advance hose.
- Start engine, increase engine speed to 1600 RPM and check ignition timing. Adjust timing to specification listed on Emission Control Information label (if necessary). Tighten distributor hold-down clamp and recheck ignition timing.
- Turn engine off and remove timing light and tachometer. Connect No. 1 spark plug lead, if disconnected. Unplug and connect distributor vacuum advance hose. Connect vacuum switch assembly wire connector.
Factory Service Tools
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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.
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