NVH App Diagnostic Procedure
Preparing for a Road Test
IMPORTANT: When Road Testing a vehicle the following precautions should be taken:
- Determine if your vehicle may require the optional Bluetooth data link adapter to diagnose engine speed related vibrations by reading the Tools Needed information.
- Visually inspect the vehicle to make sure it is safe to drive.
- Look at the tires, make sure they do not have any visible bulges and have adequate tread.
- Make sure your tires are inflated to the correct air pressure (see the tire label on the door post with the driver’s door open for the recommended tire air pressures). Low tire pressures can cause vehicle vibrations due to excessive tire sidewall flexing.
- Road Test the vehicle on a smooth level road.
- A steady throttle must be held to obtain accurate readings on vehicles equipped with an automatic transmission. This will keep torque converter clutch slippage to a minimum. Use Cruise Control if possible.
- Never place the iPhone or iPad* in a location that blocks the driver’s view of the road or of the rear view mirrors. Always educate yourself of state and local laws and regulations regarding windshield and front seat side glass mounted devices.
- Educate yourself with the basics of vehicle vibrations and terminology by studying the Vibration Diagnosis School page.
One Time Initial NVH App Setup
- If using the optional Bluetooth data link adapter, plug it in to the data link connector under the instrument panel on the driver’s side. Then enable Bluetooth Data Link in the Settings Screen.
- It is recommended that you close all other open applications by double pressing your home button and swiping upwards on the screen on all open apps.
- Receiving or placing a phone call and many other app alerts may interrupt the data recording. If an interruption occurs, a prompt to continue recording will be displayed; just select continue to keep recording. On apps with Notifications enabled, if you change your iPhone or iPad* app alert styles to banners (or None) instead of Alerts, notifications will not interrupt your recording. Select Settings, then Notifications, then scroll down the list of your apps. Look for any that have the word “Alert” in the notification style. Select the app and change the alert style to banner (see screen shot below).
- A power adapter is recommended to help maintain the iPhone or iPad* battery level while using this app since the screen Auto-lock feature is disabled by default. This setting can be adjusted in the Settings Screen.
- Start the NVH app and select Pick your Vehicle from the main menu and follow the prompts at the top of the screen.
- If your vehicle is not in the list of supported vehicles, select Unlisted Vehicle and follow the prompts at the top of the screen.
- Find an assistant to drive the vehicle while you perform diagnostics with your iPhone or iPad* from a front or rear passenger seat position.
- Place your iPhone or iPad* on a solid surface like the dashboard, floor, or center console. Alternately you can place it in a windshield or side glass suction cup attachment. NOTE: It may be necessary to move the iPhone or iPad* to other locations inside the vehicle to obtain good diagnostic readings. For example, If you can feel a vibration, but the NVH app is not displaying any diagnostic results, move the iPhone or iPad* to another location closer to where you can feel the vibration.
Windshield Suction Cup Mounting Example. WARNING: Do not block the driver’s view of the road or of the rear view mirrors.
Side Glass Suction Cup Mounting Example. Move to any window in the vehicle to detect or isolate the vibration. WARNING: Do not block the driver’s view of the road or of the rear view mirrors.
- Be sure to setup the NVH app before proceeding
- With an assistant driving the vehicle, Press the Start button in the upper right side of the screen.
- Next a prompt requesting permission to access location services while the NVH app is in use is displayed. You must allow location services to access your location for the NVH app to function.
- For Automatic Diagnostic Results, you must press the Start Recording button in the upper right side of the screen to begin recording. The screen may be in the landscape or portrait position and can be changed while testing the vehicle.
- Drive the vehicle at the speed the vibration is most noticeable. You must maintain a steady speed to reduce torque converter slip to a minimum. Avoid hills and heavy traffic for best results. Position the iPhone or iPad* in a position where it is detecting vibrations (glowing red parts on the Vehicle View Screen) while the vehicle is vibrating.
- DEFAULT VIEW: Watch the Vehicle View Screen for any glowing red components while the vehicle is experiencing a vibration. Driving for longer periods of time (up to 15 minutes) with a vibration occurring will result in more accurate diagnostic results. The minimum recommended driving time with the vibration occurring is 3 minutes. In the example below, the group of parts that rotates at the same speed as the tires is glowing red. This indicates a Tire Speed Related Vibration is occurring. The NVH app will automatically determine the most severe vibration on your vehicle and display it for you after the recording is stopped and saved.
- OPTIONAL VIEW: You can also select the Live Graph view at the bottom center of the screen to view a bar chart showing the amplitude levels for the various rotating part groups on the vehicle as well as their vibration order.
- In the example below the T1 Bar (T1 = First Order Tire Speed Related) on the graph is showing a vibration with an amplitude level of 0.265. The amplitude values can change rapidly and even disappear at times while driving.
- The bar with the highest amplitude values over the duration of the Road Test represents the group of parts on the vehicle responsible for the vibration.
- Touching any bar on the bar graph will cause context-sensitive diagnostic and repair information for that specific type of vibration.
- OPTIONAL VIEW: You can also select the Live Data view at the bottom right of the screen to view a table showing frequency and the amplitude levels for the various rotating part groups on the vehicle as well as their vibration order. In the example below a frequency of 12.5Hz is highlighted red in the first column.
- Red text indicates tire speed related vibrations,
- Blue text indicates driveshaft speed related vibrations
- Green text indicates engine speed related vibrations.
- The three remaining columns display the detected instantaneous amplitude values in each of the three axes. With the screen in the landscape position facing the rear of the vehicle (as shown below):
- The X axis represents up and down vibration amplitude values
- The Y axis represents left and right vibration amplitude values
- The Z axis represents front and back vibration amplitude values.
- If you rotate screen to the portrait position, the x and y axis will swap directions of detected vibrations.
- The frequency with the highest amplitude values over the duration of the Road Test represents the group of parts on the vehicle responsible for the vibration. Ignore vibration frequencies that do not match the rotational speed or multiple orders of the parts on your vehicle,
- Selecting the “?” in the bottom left of the screen (you may need to scroll down to see it) will cause context-sensitive diagnostic and repair information for that specific type of vibration.
- When you are satisfied that the NVH app has detected vibrations (glowing red components), press the Stop Recording button in the upper right side of the screen and give the file a name and select Save. If no name is given, the date and time of day will be used instead. If Cancel is selected, no data will be saved and no diagnostic results will be displayed.
- The screen will darken momentarily while the NVH app analyzes the recorded data.
- Automatic Diagnostic Results will be displayed next. In this example, the vibration is First Order Tire Speed Related. Next, select How do I fix this Vibration at the bottom of the page. Use the information in the context sensitive help file to determine the cause of the vibration by following the step-by-step procedures contained within.
- If no vibrations were detected, repeat the Road Test with the iPhone or iPad* in a location closer to the driver. Make sure the iPhone or iPad* is contacting something solid (no seat cushions or padded interior panels).
- If using the Bluetooth data link adapter, unplug it from the data link connector under the instrument panel on the driver’s side.
After the Road Test
Access Identifying the Vibration Source by selecting Diagnostic Help, and then Diagnostic Procedures, from the NVH app main screen. Follow the instructions in the context sensitive help files to determine the source of the vibration identified on the Road Test .Visit the built-In Vibration Diagnosis School page to review vibration basics as needed.
*iPad with internal GPS (Cellular models) is needed for the NVH app to function. Cellular data service is not required. iPhone, iPod, and iPad are trademarks of Apple Inc., registered in the U.S. and other countries.
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