2003 FORD MUSTANG engine

z
Did any abnormal occurrence coincide with or proceed its appearance?
Use the information gained from the customer to accurately begin the diagnostic process.
Pre- Drive Check
It is important to do a pre- drive check before road testing the vehicle. A pre- drive check verifies that
the vehicle is relatively safe to drive and eliminates any obvious faults on the vehicle.
The pre- drive check consists of a brief visual inspection. During this brief inspection, take note of
anything that will compromise safety during the road test and make those repairs/adjustments before
taking the vehicle on the road.
Preparing for the Road Test
Observe the following when preparing for the road test:
zReview the information recorded on the NVH Diagnostic Guide. It is important to know the
specific concern the customer has with the vehicle.
z Do not be misled by the reported location of the noise/vibration. The cause can actually be
some distance away.
z Remember that the vibrating source component (originator) may only generate a small
vibration. This small vibration can in turn cause a larger vibration/noise to emanate from another
receiving component (reactor), due to contact with other components (transfer path).
z Conduct the road test on a quiet street where it is safe to duplicate the vibration/noise. The ideal
testing route is an open, low- traffic area where it is possible to operate the vehicle at the speed
in which the condition occurs.
z If possible, lower the radio antenna in order to minimize turbulence. Identify anything that could
potentially make noise or be a source of wind noise. Inspect the vehicle for add- on items that
create vibration/noise. Turn off the radio and the heating and cooling system blower.
z The engine speed is an important factor in arriving at a final conclusion. Therefore, connect an
accurate tachometer to the engine, even if the vehicle has a tachometer. Use a tachometer that
has clearly defined increments of less than 50 rpm. This ensures an exact engine speed
reading.
Verify the Customer Concern
Verify the customer concern by carrying out a road test, an engine run- up test, or both.
The decision to carry out a road test, an engine run- up test, or both depends on the type of NVH
concern. A road test may be necessary if the symptom relates to the suspension system or is sensitive
to torque. A drive engine run- up (DERU) or a neutral engine run- up (NERU) test identifies noises and
vibrations relating to engine and drivetrain rpm. Remember, a condition will not always be identifiable
by carrying out these tests, however, they will eliminate many possibilities if carried out correctly.
Road Test Klj . 5 ba
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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.
zThe 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.
z The Heavy Acceleration Test helps to determine if the concern is torque- related.
z The Neutral Coast Down Speed Test helps to determine if the concern is vehicle speed- related.
z The Downshift Speed Test helps to determine if the concern is engine speed- related.
z The Steering Input Test helps to determine how the wheel bearings and other suspension
components contribute to a vehicle speed- related concern.
z The Brake Test helps to identify vibrations or noise that are brake related.
z The Road Test Over Bumps helps isolate a noise that occurs when driving over a rough or
bumpy surface.
z 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.
z The Neutral Run- Up Test is used as a follow- up test to the Downshift Speed Test when the
concern occurs at idle.
z 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.
z The Engine Accessory Test helps to locate faulty belts and accessories that cause engine
speed- related concerns.
z 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:
zSlowly accelerate to the speed where the reported concern occurs. Note the vehicle speed, the
engine rpm and, if possible, determine the vibration frequency.
z Attempt to identify from what part of the vehicle the concern is coming.
z Attempt to identify the source of the concern.
z Proceed as necessary.
Heavy Acceleration Test
To carry out this test, proceed as follows:
zAccelerate hard from 0- 64 km/h (0-40 mph).
z Decelerate in a lower gear.
z The concern is torque related if duplicated while carrying out this test.
z Proceed as necessary. Klj . 6 ba
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Neutral Coast Down Speed Test
To carry out this test, proceed as follows:
zDrive at a higher rate of speed than where the concern occurred when carrying out the Slow
Acceleration Test.
z Place the transmission in NEUTRAL and coast down past the speed where the concern occurs.
z The concern is vehicle speed- related if duplicated while carrying out this test. This eliminates
the engine and the torque converter as sources.
z If the concern was not duplicated while carrying out this test, carry out the Downshift Speed
Test to verify if the concern is engine speed related.
z Proceed as necessary.
Downshift Speed Test
To carry out this test, proceed as follows:
zShift into a lower gear than the gear used when carrying out the Slow Acceleration Test.
z Drive at the engine rpm where the concern occurs.
z The concern is engine speed related if duplicated while carrying out this test. This eliminates the
tires, wheels, brakes and the suspension components as sources.
z If necessary, repeat this test using other gears and NEUTRAL to verify the results.
z Proceed as necessary.
Steering Input Test
To carry out this test, proceed as follows:
zDrive at the speed where the concern occurs, while making sweeping turns in both directions.
z If the concern goes away or gets worse, the wheel bearings, hubs, U- joints (contained in the
axles of 4WD applications), and tire tread wear are all possible sources.
z Proceed as necessary.
Brake Test
To carry out this test, proceed as follows:
zWarm the brakes by slowing the vehicle a few times from 80–32 km/h (50–20 mph) using light
braking applications. At highway speeds of 89–97 km/h (50– 60 mph), apply the brake using a
light pedal force.
z Accelerate to 89–97 km/h (55–60 mph).
z Lightly apply the brakes and slow the vehicle to 30 km/h (20 mph).
z A brake vibration noise can be felt in the steering wheel, seat or brake pedal. A brake noise can
be heard upon brake application and diminish when the brake is released.
Road Test Over Bumps
To carry out this test, proceed as follows: Klj . 7 ba
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z
Drive the vehicle over a bump or rough surface one wheel at a time to determine if the noise is
coming from the front or the back and the left or the right side of the vehicle.
z Proceed as necessary.
Neutral Engine Run- Up (NERU) Test
To carry out this test, proceed as follows:
zInstall a tachometer.
z Increase the engine rpm up from an idle to approximately 4000 rpm while in PARK on front
wheel drive vehicles with automatic transmissions, or NEUTRAL for all other vehicles. Note the
engine rpm and, if possible, determine the vibration frequency.
z Attempt to identify what part of the vehicle the concern is coming from.
z Attempt to identify the source of the concern.
z Proceed as necessary.
Drive Engine Run- Up (DERU) Load Test
To carry out this test, proceed as follows:
z WARNING: Block the front and rear wheels, and apply the parking brake and the
service brake, or injury to personnel can result.
CAUTION: Do not carry out the Engine Load Test for more than five seconds or
damage to the transmission or transaxle can result.
Block the front and rear wheels.
z Apply the parking brake and the service brake.
z Install a tachometer.
z Shift the transmission into DRIVE, and increase and decrease the engine rpm between an idle
to approximately 2000 rpm. Note the engine rpm and, if possible, determine the vibration
frequency.
z Repeat the test in REVERSE.
z If the vibration/noise is duplicated when carrying out this test, inspect the engine and
transmission or transaxle mounts.
z If the concern is definitely engine speed- related, carry out the Engine Accessory Test to narrow
down the source.
z Proceed as necessary.
Engine Accessory Test
To carry out this test, proceed as follows:
z WARNING: Block the front and rear wheels, and apply the parking brake and the
service brake, or injury to personnel can result.
CAUTION: Limit engine running time to one minute or less with belts removed or
serious engine damage will result. Klj . 8 ba
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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.
z Increase the engine rpm to where the concern occurs.
z If the vibration/noise is duplicated when carrying out this test, the belts and accessories are not
sources.
z 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:
zTest 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.
z Park the vehicle where testing will occur. The vehicle must remain at or below the concern
temperature (if known) for 6- 8 hours.
z Before starting the engine, conduct a visual inspection under the hood.
z 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.
z Start the engine.
z 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.
z GO to Symptom Chart — Idle Noise/Vibration to assist with the diagnosis.
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.
zVerify the "symptom".
z 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. Klj . 9 ba
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z
After determining the "system", use the diagnostic tools to identify the worn or damaged
"components".
z After identifying the "components", try to find the "cause" of the failure.
Once the concern is narrowed down to a symptom/condition, proceed to NVH Condition and Symptom
Categories.
NVH Condition and Symptom Categories
A good diagnostic process is a logical sequence of steps that lead to the identification of a causal
system. Use the condition and symptom categories as follows:
zIdentify the operating condition that the vehicle is exhibiting.
z Match the operating condition to the symptom.
z Verify the symptom.
z Identify which category or system could cause the symptom.
z Refer to the diagnostic symptom chart that is referred to.
Operating Condition— Vehicle is Not Moving
1. Static operation zNoise occurs during component/system functioning. GO to Symptom Chart — Squeak
and Rattle .
2. While cranking 1. Grinding or whine, differential ring gear or starter motor pinion noise. GO to Symptom Chart — Engine Noise/Vibration .
2. Rattle. Exhaust hanger, exhaust heat shield or A/C line noise. GO to Symptom Chart —
Squeak and Rattle .
3. Vibration. Acceptable condition.
3. At idle zIdle noise. GO to Symptom Chart — Idle Noise/Vibration .
z Idle vibration or shake. GO to Symptom Chart — Idle Noise/Vibration .
4. During Gear Selection 1. Vehicle parked on a steep incline. Acceptable noise.
2. Vehicle parked on a flat surface. GO to Symptom Chart — Driveline Noise/Vibration .
3. Vehicle with a manual transmission. GO to Symptom Chart — Transmission (Manual)
and Transfer Case Noise/Vibration .
Operating Condition— Vehicle is Moving
1. Depends more on how the vehicle is operated 1. Speed related
„Related to vehicle speed
„Pitch increases with vehicle speed. GO to Symptom Chart — Tire
Noise/Vibration .
„ Noise occurs at specific vehicle speed. A high- pitched noise (whine). GO to
Symptom Chart — Driveline Noise/Vibration . Klj . 10 ba
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„
Loudness proportional to vehicle speed. Low- frequency noise at high
speeds, noise and loudness increase with speed. GO to Symptom Chart —
Driveline Noise/Vibration .
„ A low- pitched noise (drumming). GO to Symptom Chart — Engine
Noise/Vibration .
„ Vibration occurs at a particular speed (mph) regardless of acceleration or
deceleration. GO to Symptom Chart — Tire Noise/Vibration .
„ Noise varies with wind/vehicle speed and direction. GO to Symptom Chart — Air Leak and Wind Noise .
„ Related to engine speed.
„Noise varies with engine rpm. GO to Symptom Chart — Engine
Noise/Vibration .
„ Vibration occurs at a particular speed (mph) regardless of engine speed
(rpm).
2. Acceleration
„Wide open throttle (WOT)
„Engine induced contact between components. Inspect and repair as
necessary.
„ Noise is continuous throughout WOT. Exhaust system or engine ground
out. GO to Symptom Chart — Engine Noise/Vibration .
„ Light/moderate acceleration
„Tip- in moan. Engine/exhaust noise. GO to Symptom Chart — Engine
Noise/Vibration .
„ Knock-type noise. GO to Symptom Chart — Engine Noise/Vibration .
„ Driveline shudder. GO to Symptom Chart — Driveline Noise/Vibration .
„ Engine vibration. GO to Symptom Chart — Engine Noise/Vibration .
3. Turning noise. GO to Symptom Chart — Steering Noise/Vibration .
4. Braking
„Clicking sound is signaling ABS is active. Acceptable ABS sound.
„ A continuous grinding/squeal. GO to Symptom Chart — Brake Noise/Vibration .
„ Brake vibration/shudder. GO to Symptom Chart — Brake Noise/Vibration .
5. Clutching
„A noise occurring during clutch operation. GO to Symptom Chart — Transmission
(Manual) and Transfer Case Noise/Vibration .
„ Vibration. GO to Symptom Chart — Transmission (Manual) and Transfer Case
Noise/Vibration .
6. Shifting
„Noise or vibration condition related to the transmission (automatic). GO to
Symptom Chart — Transmission (Automatic) Noise/Vibration .
„ Noise or vibration related to the transmission (manual). GO to Symptom Chart —
Transmission (Manual) and Transfer Case Noise/Vibration .
7. Engaged in four- wheel drive. GO to Symptom Chart — Transmission (Manual) and
Transfer Case Noise/Vibration .
8. Cruising speeds
„Accelerator pedal vibration. GO to Symptom Chart — Engine Noise/Vibration .
„ Driveline vibration. GO to Symptom Chart — Driveline Noise/Vibration .
„ A shimmy or shake. GO to Symptom Chart — Tire Noise/Vibration .
9. Driving at low/medium speeds Klj . 11 ba
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components as necessary.
z Broken
powertrain
mounts. z
INSPECT the powertrain
mounts. INSTALL new
mounts as necessary.
REFER to Section 303 - 01A
for 3.8L engines or
Section 303 - 01B for 4.6L (2V)
engines.
z Idle speed too
high. z
CHECK for the correct idle
speed.
z Driveline clunk—
occurs as the vehicle
starts to move
forward following a
stop z
Worn or galled
driveshaft slip-
yoke splines. z
CLEAN and INSPECT the
splines of the yoke for a
worn or galled condition.
INSTALL a new yoke as
necessary. REFER to
Section 205 - 01 .
z Worn or galled
driveshaft and
coupling shaft
splines. z
CLEAN and INSPECT the
splines of the driveshaft and
coupling shaft for a worn or
galled condition. INSTALL a
new driveshaft assembly as
necessary. REFER to
Section 205 - 01 .
z Loose rear leaf
spring U- bolts. z
CHECK the U- bolts for
loose nuts. TIGHTEN to
specification. REFER to
Section 204 - 02 .
z Driveline clunk (FWD
vehicles)—occurs
during acceleration or
from cruise to
coast/deceleration z
Damaged or
worn inboard
constant velocity
(CV) joint. z
INSPECT the inboard CV
joint and boot. REPAIR or
INSTALL a new CV joint as
necessary.
z Driveline clunk (4WD
vehicles)—occurs
during shift- on-the- fly
engagement z
Clutch relay.
z Shift motor.
z Transfer case.
z GEM. z
CHECK the 4WD
engagement system.
REPAIR or INSTALL new
components as necessary.
z Clicking, popping or
grinding— occurs
while vehicle is
turning z
Inadequate or
contaminated
lubrication in the
(CV) joints. z
CHECK the CV boots and
joints for wear or damage.
REPAIR or INSTALL new
components as necessary.
z Another
component
contacting the
halfshaft. z
CHECK the halfshafts and
the area around the
halfshafts. REPAIR as
necessary.
z Brake
components. z
INSPECT the front brakes
for wear or damage.
REPAIR as necessary.
REFER to Section 206 - 03 .
z Steering
components. z
INSPECT the drag link,
inner and outer tie- rods or
idler arm for wear or
damage. REPAIR as
necessary. REFER to
Section 211 - 02 .
z Suspension
components. z
INSPECT the upper and
lower ball joints for wear or
damage. REPAIR as
necessary. REFER to Klj . 19 ba
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