Diagnose Rough Idle Only

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2004 Ford RV Cutaway, 2004 Ford Pickup, 2004 Ford F550 Super Duty, 2004 Ford F450 Super Duty, and 2004 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.

This test will help diagnose weak cylinders/injectors by allowing the scan tool operator to interrupt injectors individually. This is performed by using scan tools to interrupt injector output to the engine cylinder that corresponds to the number on the injector PID.

A performance diagnostic sheet should be completed before using this tool. High ICP after the high idle test (test 12 on the performance diagnostics sheet to indicate oil aeration), low fuel pressure, bad dual-mass flywheel, and high crankcase pressure are just a few of the possibilities that can cause a rough idle. After completing the performance diagnostic sheet, if there is no direction given for corrective action and rough idle is present, use the enhanced diagnostic ability of the Injector Interrupt.