Jeep Engines - Oljeep

4.2L IN-LINE 6 (IGNITION SYSTEM) 329IGNITION SYSTEM TIMINGA graduated timing degree scale located on the timing casecover is used for reference when timing the ignition system.A milled index notch on the vibration damper is used toalign the No. 1 cylinder ignition position of the crankshaftwith the correct timing degree mark on the graduated scale.Magnetic Timing ProbeA magnetic timing probe socket is provided and is integralwith the timing degree scale for use with a special magnetictiming probe. This special probe detects the milled notch onthe vibration damper. The probe is inserted through theprobe socket until it contacts the vibration damper.Ignition timing can then be obtained from a meter or computerprintout, depending on the type of equipment being used.The probe socket is located at 9.5" ATDC, and theequipment is calibrated to compensate for this location.DO NOT use the timing probe socket as a reference to checkthe ignition timing when using a conventional timing light.Ignition Timing ProcedureThe ignition timing can be adjusted according to thefollowing primary timing procedure.1. Set the parking brake. Shift automatic transmissions toPARK and manual transmissions to the NEUTRALposition.2.3.4.Start the engine and allow it to attain normal operatingtemperature. Ensure that the A/C is turned OFF, ifequipped.With the ignition switch OFF, connect an ignitiontiming light and a tachometer. (If the timing light hasan adjustable advance control feature, turn the controlto the OFF position.)Disconnect the 4" and IO" Hg (CEC System) vacuumswitch assembly wire connectors (located at the top ofthe cylinder head cover).5. Disconnect and plug the distributor vacuum advance hose.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put your hands near the pulleys, belts or the fan. DONOT wear loose clothing.6. Start the engine.7. Increase the engine speed to 1,600 rpm and checkignition timing. If necessary, adjust the timing to thespecifications listed on the Emission Control Informationlabel. Also, refer to the ignition advance curveillustrations found in your vehicle's service manual.8.Tighten the distributor hold-down clamp and verifythat the ignition timing is correct.9. Turn the engine OFF and remove the timing light andtachometer.10. Connect the No. 1 spark plug wire, if disconnected.Connect the hose to the distributor vacuum advancemechanism. Connect the wire connector to the vacuumswitch assembly.Note: Ignition timing can also be adjusted according to thefollowing alternate procedure.Alternate Timing ProcedureThis alternate timing procedure does not require enginespeed be increased to 1,600 rpm.1.2.3.4.5.6.7.8.9.Set the parking brake.Shift automatic transmissions to PARK and manualtransmissions to the NEUTRAL position.Start the engine and allow it to attain normal operatingtemperature. Ensure that the A/C is turned OFF, ifequipped.With the ignition switch OFF, connect an ignitiontiming light and a tachometer. (If the timing light hasan adjustable advance control feature, turn the controlto the OFF position.)Disconnect the 4" Hg vacuum switch hose (located atthe top of the cylinder head cover) and plug the hoseopening. (The 4" Hg vacuum switch has black and redwires connected to it.)Disconnect the distributor vacuum advance hose andconnect the hose to the 4" Hg vacuum switch.Disconnect the knock sensor wire connector andconnect the wire connector to the cylinder block(GROUND) with a jumper wire.Grounding the knock sensor wire connector preventselectromagnetic interference (EMI) from causingerroneous reactions by the fuel feedback system microcomputerunit (MCU).Start the engine.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan.,DO NOT put your hands near the pulleys, belts or thefan. DO NOT wear loose clothing.With the engine at idle speed, check the timing. Ifnecessary, adjust the timing one degree higher than thespecifications listed on the Emission ControlInformation label. Also, refer to the ignition advancecurve illustrations.Note: With the alternate timing procedure, the basic timingmust be one degree higher than the specification listed onthe Emission Control Information label. For example, if thetiming specification is listed as 6" (+2") at 1,600 rpm, thealternate procedure requires 7" (+2") at idle speed.