Test 4: Intake Restriction: Purpose
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Ford RV Cutaway, 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, and 2003 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.
This is a visual inspection to determine if an air intake restriction is contributing to a low power condition. If engine does have a high air intake restriction, a large amount of Black or Blue smoke will be produced.