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Ford Engine Spark Knock Under Light Load and Acceleration
Some 1997-2008 Ford vehicles equipped with 3.8L, 3.9L or 4.2L engines with Split Port Intake Manifold Runner Control (IMRC) may exhibit spark knock under light load and acceleration.
Inspect for disconnected IMRC actuator rods. Follow the service steps to correct this condition.
1) Check both right hand and left hand side IMRC rods to be sure
they are properly attached to the actuator motor and intake manifold
2) If the IMRC actuator rods are found to be connected properly, do not continue with information.
3) If any IMRC actuator rods are disconnected, refer to service manual.
4) If any IMRC actuator rod linkages are found disconnected, replace all four linkage rod retainers (Figure 1).
Some or all of this information was provided by the Automotive
Parts Remanufacturers Association (APRA). For more information on
technical bulletins available through APRA call 703-968-2772 or visit www.AutoBulletins.com.