Adjusting the timing on a Jeep Grand Cherokee requires special tools and an understanding of engine mechanics. Changing the timing on a Jeep Grand Cherokee with distributor-less ignition requires professional reprogramming of the powertrain control module. This guide covers Jeep Grand Cherokee models with distributed ignition only.
Instructions
1. Start the car and turn off any accessories such as lights, climate control and the radio. Allow the car to reach normal operating temperature and shut off the engine.
2. Locate the crankshaft pulley and clean off any dirt or grime to expose the timing marks. Attach the timing light to the battery if necessary and then to the number one ignition wire at the far driver's side on the four cylinder engine and at the back passenger side on six-cylinder engines. The number one ignition wire in the eight-cylinder engine is at the front passenger side.
3. Idle the Jeep Grand Cherokee engine for 2 minutes. Point the timing light at the crankshaft pulley and determine the amount of adjustment needed.
4. Loosen the distributor mounting bolts and rotate the distributor until the crankshaft timing line matches the middle mark on the timing light. Tighten the distributor mounting bolts and recheck the timing.
5. Turn the engine off and remove the timing light. Reconnect the number one ignition wire.
Tips Warnings
Forcing an engine to run out of its manufactured specified setting can cause serious and permanent damage to the engine.
Never pierce the ignition wire as misfiring or crossfiring may result.
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