Spark Plug Wire Routing for '94-up 5.0L & all 5.8L
For other TSBs, check here
ISSUE: Engine miss, spark knock, buck/jerk, surge and other driveability concerns may be caused by induction crossfire. This occurs because of improperly routed spark plug wires.
ACTION: If spark plug replacement is performed, the correct firing order and spark plug wire routing is essential to prevent the possibility of induction crossfire between cylinders. Refer to the following procedures for inspection of the spark plug wire routing and firing order. Properly reroute the spark plug wires if required.
Whenever a high-tension ignition wire is removed from a spark plug, the distributor cap, or the coil to perform a maintenance operation, Silicone Dielectric Compound must be applied to the boot before reconnection. Using a small clean screwdriver, apply a thin layer of Silicone Dielectric Compound on the entire interior surface of the boot. Do not apply compound to metal terminals.
The firing order for 1987-1993 5.0Ls is 1-5-4-2-6-3-7-8. If #7 and #8, or #2 and #4 spark plug wires are routed next to each other at the separation bracket, an induction crossfire condition can occur.
The firing order for 1994-up 5.0Ls & all 5.8Ls is 1-3-7-2-6-5-4-8 (including Coil-On-Plug). On these vehicles with distributor, the #1 and #3, or #5 and #6 spark plug wires must be separated to eliminate the possibility of an induction crossfire.
To eliminate the possibility of the coil wire becoming disconnected, route the coil wire under the spark plug wires at the distributor cap.
Distributor Clampdown 24-33 Nm; 17-25 lb-ft
Spark plug & coil wires should measure ~7KOhm/foot from the terminal inside the distributor cap to the terminal in the boot that slips over the spark plug.