Ford Fusion: Noise, Vibration and Harshness / Noise, Vibration and Harshness (NVH)

Special Service Tools)

	MASTERTECH MTS-4000 ANALYZER 257-00018
	ENGINE EAR 107-R2100 Chassis Ears JSP97170 Squeak and Rattle Kit 164-R4900
	Marksman Ultrasonic Leak Detector TRACE-9370

Diagnostic Theory

The shortest path to an accurate diagnosis is through:

Knowledge of the system, including comparison with a known good system.
System history, including repair history and usage patterns.
Condition history, especially any relation to repairs or sudden changes.
Knowledge of possible sources.
Use of a systematic diagnostic method that divides the system into related areas.

To diagnose and correct NVH symptoms, the following are required:

A road or system test to determine the exact nature of the symptom.
Analysis of possible causes.
Testing to confirm the cause.
Correction of the identified symptom.
A road test or system test to verify that the cause has been eliminated or returned within acceptable limits.

Diagnostic Procedure Overview

Qualifying the symptom by the specific sensation present can help narrow down the cause. Always use the 'symptom' to 'system' to 'component' to 'cause' diagnostic method. This diagnostic method separates the problem into adjacent areas to correct the customer concern.

Verify the "symptom."
Determine which "systems" may cause the "symptom" using the diagnostic tools described in this section.
After determining the possible "systems," refer to the appropriate section in this manual to identify worn or damaged "components."
After identifying the components, determine the cause of the malfunction.

Tools and Methods

Diagnostic tools allow systematic collection of the information required for accurate diagnosis and repair of NVH concerns. Remember that the vibration source component (initiator) may produce only a small vibration. This small vibration, in turn, may cause a large vibration/noise emitted by another receiving component (reactor) due to contact with other components (transfer path). For best results, perform the test as follows:

Perform a road test with the vibration sensor inside the vehicle.
Place the sensor in the vehicle according to the sensation felt.
- If the condition is felt through the steering wheel, the source is most likely at the front of the vehicle.
- Vibration felt only in the seat or floor is most likely from the transmission, drive axle, rear wheels or tires.
Record the readings. Also note when the condition begins, when it reaches maximum intensity, and whether it tends to decrease above/below a certain speed.
- If the vibration symptom is related to vehicle speed, calculate the frequency from tire and wheel revolutions per minute (rpm) and the driveshaft.
- Frequencies with an amplitude reading of 0.06 g or less are barely perceptible NVH levels. No corrective action is required.
Place the vibration sensor on or near the suspect area outside the vehicle.
Continue the road test by driving at the speed at which the symptom occurs, and take another reading.
Compare the readings.
- A frequency match indicates the problem component or area.

The following diagnostic tools and methods can be used separately or in combination with each other to help diagnose NVH symptoms. They are listed in order of preference for ease of use in detecting these symptoms.

Noise, Vibration and Harshness (NVH) Analyzer (Vetronix)

The MTS 4000 and MTS 4100 NVH analyzers are tools that help identify and isolate noise, vibration or harshness in the vehicle. They measure noise and vibration data and compare it with data obtained from the vehicle PCM, as well as user-entered vehicle variants such as pulley size, axle ratio and tire size, to indicate possible sources. The MTS 4000 and MTS 4100 have the following features:

Interface with the vehicle computer system
Support and storage of vibration data from 1 or 2 accelerometers
Support and storage of noise data from 2 microphones
Provides a photo-tachometer for the driveshaft balancing function
Provides a strobe output capable of driving a standard timing light
Contains a real-time clock circuit that provides time and date information used to label test data.
Capable of printing to an external printer and communicating with a personal computer.
Can be powered from various power sources: cigarette lighter, AC mains or internal battery pack.

The MTS 4000 and MTS 4100 NVH analyzers have 4 main operating modes. The first is for vibration diagnosis. In this mode, data is measured from 1 or 2 accelerometers simultaneously while receiving data from the vehicle. It then performs a frequency analysis of the accelerometer data and compares the vibration frequency with the frequencies associated with the various rotating components within the vehicle. Data can be presented in 4 different display modes: main component, histogram, frequency spectrum or waterfall. All display mode formats contain the same common elements, such as amplitude.

The second is for noise diagnosis. This mode measures noise from 1 or 2 microphones simultaneously. All noise measurements are given in decibels (dB). All frequency bands used for noise measurement are the same as those used for vibration measurement up to 1000 hertz (Hz).

Third, strobe light. A strobe light or a standard timer can be connected to the analyzer to provide a means of measuring rotational speed. The strobe function is used to isolate the vibration source.

Electronic Vibration Analyzer (EVA)

The Electronic Vibration Analyzer (EVA) is a portable electronic scanning instrument that helps locate the source of unacceptable vibrations. The vibration sensor can be installed remotely at any location in the vehicle for testing purposes. The device displays the 3 most common vibration frequencies and their corresponding amplitudes simultaneously. The bar graph provides a visual representation of the relative signal strength (amplitude) of each displayed vibration and its relative overload. The keypad is designed so that the Electronic Vibration Analyzer (EVA) is easy to program and operate. Some of the functions include the ability to average readings, as well as record, playback, and freeze readings. The Electronic Vibration Analyzer (EVA) has a strobe balance function that can be used to detect imbalance of rotating components, such as the driveshaft or engine accessories.

Record the readings taken with the diagnostic tool.

Frequencies should be read in the "average" mode.
The frequency range is plus or minus 2 hertz (Hz). For example, a reading of 10 hertz (Hz) may be displayed as anywhere from 8 hertz (Hz) to 12 hertz (Hz).

Vibrate Software

Vibrate Software is a diagnostic tool that helps accurately identify the source of unacceptable vibrations. The engine crankshaft is the main reference for vibration diagnosis. Each rotating component will have an angular speed that is greater than, less than, or equal to the speed of the engine crankshaft. Vibrate® Software calculates the angular speed of each component and graphically presents these speeds on the computer screen and on a printed vibration worksheet. The following steps outline how Vibrate® Software helps diagnose vibration symptoms:

Enter the vehicle information. Vibrate will perform all calculations and display a graph showing the tire and driveline vibrations.
Print the vibration graph. The printed graph must be used during the road test.
Road test the vehicle at the speed at which the vibration is most noticeable. Record the vibration frequency in revolutions per minute (RPM) and the engine speed in revolutions per minute (RPM) on the worksheet graph. The point on the graph where the vibration frequency in revolutions per minute (RPM) and the engine speed in revolutions per minute (RPM) readings intersect indicates the specific group of components causing the symptom.
- A frequency meter capable of measuring vibration frequency and revolutions per minute (RPM) is required.
Provides diagnostic procedure charts to assist in testing components.

Reed Tachometer

The reed tachometer is a handheld vibration indicator that helps identify the source of unacceptable vibrations. The vibration sensor can be placed at any location in the vehicle for testing purposes. The reed tachometer contains several reeds tuned to vibrate or resonate at different frequencies in the range of 10 to 80 hertz (Hz), or 600 to 4800 revolutions per minute (RPM). Although the reed tachometer can measure several frequencies, it does not measure amplitude.

Synchrometer

The synchrometer measures frequency in hertz (Hz) and revolutions per minute (RPM). To use the synchrometer, place it on any vibrating component and slowly extend the wire outward while turning the knob. As the wire length changes, so does its natural frequency. Find the wire length at which it vibrates with maximum amplitude. This frequency corresponds to the frequency of the vibrating component. Read the frequency for this wire length.

Engine EAR / Chassis EAR Combination

The ChassisEAR is an electronic listening device used to quickly locate noise and its source under the vehicle during road tests. The ChassisEAR can identify the noise and location of a damaged or worn wheel bearing, constant velocity joint, brake, spring, or axle bearing.

EngineEAR Main Module

The EngineEAR is an electronic listening device used to detect even faint noises. The EngineEAR can detect noise from damaged or worn bearings in alternators, coolant pumps, air conditioning compressors, and power steering pumps. It is also used to identify noisy lifters, exhaust manifold leaks, chipped gear teeth, and wind noise. The EngineEAR consists of a sensor tip, amplifier, and headphones. The directional sensor tip is used to listen to various components. Aim the sensor tip at the suspected component and adjust the volume with the amplifier. Placing the tip in direct contact with the component will detect structural noise and vibration generated by or passing through the component. Different volume levels may reveal different sounds.

Mechanic's Stethoscope

A mechanical stethoscope is an inexpensive tool for detecting noises in engines and other moving parts. It can be used to diagnose worn gears, faulty valves, coolant pump failure, damaged gaskets, squeaking bearings, and body noise.

Squeak and Rattle Repair Kit

The squeak and rattle repair kit contains lubricants and self-adhesive materials that can be used to eliminate internal and external squeaks and rattles. The kit consists of the following materials:

PVC tape (soft foam)
Urethane (hard foam) tape
Flocked (black fuzzy) tape
Ultra-high molecular weight (UHMW) tape (matte)
Squeak and rattle oil tube
Squeak and rattle lubricant tube

Leak Detector

The leak detector is used to locate wind noise caused by leaks and gaps in areas where there is weatherstripping or other sealing material. It is also used to detect air conditioning leaks, vacuum leaks, and fuel vapor canister noise. The leak detector consists of a multi-directional transmitter (operating in the ultrasonic range) and a handheld detector. The transmitter is placed inside the vehicle. Outside the vehicle, use the handheld detector to sweep the suspected leak area. As you approach the leak source, an audible signal sounds that increases in both speed and frequency.

1: Customer Interview

The diagnostic process begins with a customer interview. The service advisor must obtain as much information about the concern as possible and take a test drive with the customer. There are many ways a customer may describe a NVH concern, and this will help minimize confusion caused by descriptive language differences. It is important that the concern is interpreted correctly and the customer's descriptions are recorded. During the interview, ask the following questions:

When was it first noticed?
Did it appear suddenly or gradually?
Did any abnormal event coincide with or precede its appearance?

Use the information obtained from the customer to accurately begin the diagnostic process.

2: Pre-Drive Check

Before the road test, it is important to perform a pre-drive check. A pre-drive check confirms that the vehicle is safe to drive and eliminates obvious vehicle faults.

The pre-drive check consists of a brief visual inspection. During this brief inspection, note anything that could compromise safety during the road test and perform repair/adjustment before driving the vehicle on the road.

3: Road Test Preparation

When preparing for the road test, note the following:

Review the information recorded in the NVH Diagnostic Guide. It is important to know exactly what concerns the customer about the vehicle.
Do not be misled by the reported location of the noise/vibration. The actual cause may be some distance away.
Remember that the vibrating source component (generator) may produce only a small vibration. This small vibration may, in turn, cause larger vibration/noise from another receiving component (reactor) through contact with other components (transmission path).
Perform the road test on a quiet street where it is safe to duplicate the vibration/noise. The ideal test route is an open, low-traffic area where the vehicle can be driven at the speed at which the condition occurs.
If possible, lower the radio antenna to minimize turbulence. Identify anything that could potentially create noise or be a source of wind noise. Inspect the vehicle for additional items that may create vibration/noise. Turn off the radio and the heating and cooling system fan.

4. Confirm the Customer Concern

Confirm the customer's concern by performing a road test.

A road test may be required if the symptom relates to the suspension system or is sensitive to torque. Remember, the condition will not always be identifiable during these tests; however, they will eliminate many possibilities if performed correctly.

5: Road Test

A brief overview of each test is provided below. This overview helps to quickly determine the most appropriate process required for a successful diagnosis. After reviewing this information, select and perform the appropriate test(s), proceeding to the next step of this process. Perform the test(s) applicable to the engine and transmission components the vehicle is equipped with, hybrid, gasoline or electric.

The slow acceleration test is usually the first test to perform when diagnosing an NVH concern, especially when a road test with the customer is not possible.
The Heavy Acceleration Test helps determine whether the concern is related to torque.
The Neutral Coast-Down Test helps determine whether the concern is related to vehicle speed.
The Steering Test helps determine how the steering wheel, bearings, and other suspension components contribute to the vehicle speed concern.
The Brake Test helps determine vibrations or noise related to the brakes.
Engine acceleration tests consist of the NERU test and the Engine Load test. These tests help determine whether the symptom is dependent on engine speed.
The NERU test is used as a follow-up test after the downshift test when the symptom occurs at idle.
The DERU load test helps determine whether the vibration/noise is sensitive to engine load or torque. It also helps reproduce speed-related engine symptoms that cannot be reproduced when performing the Neutral Acceleration test or the Neutral Coast-Down test.
The Bump Road Test helps isolate noise that occurs when driving over rough or bumpy surfaces.
To determine whether the noise is coming from the engine and/or transaxle (for example, a whine concern), it may be helpful to shift into neutral while driving when conditions permit.
The Vehicle Cold Soak Procedure helps determine concerns that occur during initial start-up and after a long period of time between vehicle use.