Before carrying out extensive tests to isolate poor running problems, check connections of spark plug wires. This is especially important if plugs, wires, distributor, etc., have been disturbed recently for service. Obviously, this is not applicable to the wireless 4.7L engine.
To avoid problems, remove and tag the spark plug wires one at a time to ease reinstallation.
For vehicles with an extensive service history, keep in mind that the distributor could have been removed previously and rewired. The resultant wiring would hold the correct firing order, but could change the relative placement of the plug towers in relation to the engine. For this reason, it is very important that you label all wires before disconnecting any of them. Also, before removal, compare the current wiring with the accompanying illustrations. If the current wiring does not match, make notes in your book to reflect how your engine is wired.
Fig. 2.5L Engine Firing Order: 1-3-4-2 Distributor Rotation: Clockwise
Fig. 3.9L Engine Firing Order: 1-6-5-4-3-2 Distributor Rotation: Clockwise
Fig. 5.2L and 5.9L Engines Firing Order: 1-8-4-3-6-5-7-2 Distributor rotation: Clockwise
Fig. 4.7L Engine Firing Order: 1-8-4-3-6-5-7-2 Distributorless Ignition
Fig. 8.0L Engine Firing Order: 1-10-9-4-3-6-5-8-7-2- Distributorless Ignition
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