Ford 2003 Mustang Workshop Manual page 53

NOTE: It may be necessary to have the customer ride along or drive the vehicle to point out the
concern. During the road test, take into consideration the customer's driving habits and the driving
conditions. The customer's concern just may be an acceptable operating condition for that vehicle.
The following is a brief overview of each test in the order in which it appears. A review of this
information helps to quickly identify the most appropriate process necessary to make a successful
diagnosis. After reviewing this information, select and carry out the appropriate test(s), proceeding to
the next step of this process.
The Slow Acceleration Test is normally the first test to carry out when identifying an NVH
concern, especially when a road test with the customer is not possible.
The Heavy Acceleration Test helps to determine if the concern is torque-related.
The Neutral Coast Down Speed Test helps to determine if the concern is vehicle speed-related.
The Downshift Speed Test helps to determine if the concern is engine speed-related.
The Steering Input Test helps to determine how the wheel bearings and other suspension
components contribute to a vehicle speed-related concern.
The Brake Test helps to identify vibrations or noise that are brake related.
The Road Test Over Bumps helps isolate a noise that occurs when driving over a rough or
bumpy surface.
The Engine Run-Up Tests consist of the Neutral Run-Up Test and the Engine Load Test. These
tests help to determine if the concern is engine speed-related.
The Neutral Run-Up Test is used as a follow-up test to the Downshift Speed Test when the
concern occurs at idle.
The Engine Load Test helps to identify vibration/noise sensitive to engine load or torque. It also
helps to reproduce engine speed-related concerns that cannot be duplicated when carrying out
the Neutral Run-Up Test or the Neutral Coast Down Test.
The Engine Accessory Test helps to locate faulty belts and accessories that cause engine
speed-related concerns.
The Vehicle Cold Soak Procedure helps to identify concerns occurring during initial start-up and
when an extended time lapse occurs between vehicle usage.
Slow Acceleration Test
To carry out this test, proceed as follows:
Slowly accelerate to the speed where the reported concern occurs. Note the vehicle speed, the
engine rpm and, if possible, determine the vibration frequency.
Attempt to identify from what part of the vehicle the concern is coming.
Attempt to identify the source of the concern.
Proceed as necessary.
Heavy Acceleration Test
To carry out this test, proceed as follows:
Accelerate hard from 0-64 km/h (0-40 mph).
Decelerate in a lower gear.
The concern is torque related if duplicated while carrying out this test.
Proceed as necessary.