Engine - Spark Knock/Engine Miss

90ford04

Article No. 90-4-14

^ ENGINE MISS - 5.0L - SPARK PLUG WIRE INDUCTION CROSS FIRE

^ SPARK KNOCK - 5.0L - SPARK PLUG WIRE INDUCTION CROSS FIRE

LIGHT TRUCK: 1987-90 BRONCO, E-150, E-250, F-150, F-250

ISSUE: Spark knock or an engine miss may be caused by induction cross fire. This occurs because of misrouted spark plug wires. The firing order of the 5.0L engine is such that the # 8 spark plug follows the # 7 spark plug. Placing wires # 8 and # 7 next to each other at the separating bracket may induce cross fire. Eventually, cross fire will cause electrode deterioration of the # 8 spark plug.

ACTION: Check the positions of the # 7 and # 8 spark plug wires and reroute correctly if required. Refer to the following procedure for service details.

Figure 1:

Figure 2:

1. Inspect the routing of the ignition wiring. Refer to Figures 1 & 2 for the correct wiring order and layout.

2. Make any ignition wiring changes that are required.

3. Check the # 8 spark plug for electrode deterioration.

4. Replace the # 8 spark plug if it is damaged.

PART NUMBER PART NAME CLASS

ASF-42-C Spark Plug B

OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Eligible Under Basic Warranty Coverage
OPERATION DESCRIPTION TIME
900414A Reroute Spark Plug Wire 0.4 Hr.
F Series, Bronco
900414B Reroute Spark Plug Wire 0.6 Hr.
Econoline
DEALER CODING
BASIC PART NO. CONDITION CODE
12286 43
OASIS CODES: 630300, 630301, 620300, 632500