Ford 2003 Mustang Workshop Manual page 56

NOTE: A serpentine drive belt decreases the usefulness of this test. In these cases, use a
vibration analyzer, such as the VA, to pinpoint accessory vibrations. An electronic listening
device, such as an EngineEAR, will also help to identify noises from specific accessories.
Remove the accessory drive belts.
Increase the engine rpm to where the concern occurs.
If the vibration/noise is duplicated when carrying out this test, the belts and accessories are not
sources.
If the vibration/noise was not duplicated when carrying out this test, install each accessory belt,
one at a time, to locate the source.
Vehicle Cold Soak Procedure
To carry out this procedure, proceed as follows:
Test preparations include matching customer conditions (if known). If not known, document the
test conditions: gear selection and engine rpm. Monitor the vibration/noise duration with a watch
for up to three minutes.
Park the vehicle where testing will occur. The vehicle must remain at or below the concern
temperature (if known) for 6-8 hours.
Before starting the engine, conduct a visual inspection under the hood.
Turn the key on, but do not start the engine. Listen for the fuel pump, anti-lock brake system
(ABS) and air suspension system noises.
Start the engine.
CAUTION: Never probe moving parts.
Isolate the vibration/noise by carefully listening. Move around the vehicle while listening to find
the general location of the vibration/noise. Then, search for a more precise location by using a
stethoscope or EngineEAR.
GO to Symptom Chart — Idle Noise/Vibration
6: Check OASIS/TSBs/Repair History
After verifying the customer concern, check for OASIS reports, TSBs and the vehicle repair history for
related concerns. If information relating to a diagnosis/repair is found, carry out the procedure(s)
specified in that information.
If no information is available from these sources, carry out the vehicle preliminary inspection to
eliminate any obvious faults.
7: Diagnostic Procedure
Qualifying the concern by the particular sensation present can help narrow down the concern. Always
use the "symptom" to "system" to "component" to "cause" diagnosis technique. This diagnostic method
divides the problem into related areas to correct the customer concern.
Verify the "symptom".
Determine which "system(s)" can cause the "symptom".
If a vibration concern is vehicle speed related, the tire and wheel rpm/frequency or
driveshaft frequency should be calculated.
If a vibration concern is engine speed related, the engine, engine accessory or engine
firing frequencies should be calculated.
to assist with the diagnosis.