EVA "Auto Mode" Vibration Diagnosis

WARNING, THIS METHOD OF DIAGNOSIS CAN BE INACCURATE.  Click here to find out why!

Click here to use "Normal Mode" diagnostics instead (recommended).

To begin Diagnosis, there are a few preliminary steps to be performed.

• Gather information from the vehicle's driver about when the vibration is most noticeable.

• Gather vehicle information , specifically, the tire size, the vehicle speed when the vibration is occurring, and the axle gear ratio(s).

• Bring the EVA with the EVA2 memory cartridge, the EVA with the "Smart" memory cartridge, or the EVA2 on the road test.

• Inspect the vehicle to insure it is safe to drive.  Look at the tires, make sure they are not separating and that they have the correct air pressure in them.

• Place the EVA’s sensor with the magnetic attachment on the seat frame to begin the road test. It may be necessary to move the sensor to other locations on the vehicle to obtain good readings of frequency and amplitude.

Place the sensor's magnetic base on the metal seat frame.

TIP: Think if the sensor as a "vibration sniffer"; the closer you get to the source of the vibration, the higher the amplitude level will be.  If you don't get a good reading with the sensor on the seat frame, move it somewhere else.

Select one of the following options:

• If you are using the EVA with the EVA2 Version 3.0 memory cartridge, jump to here.
• If you are using the EVA with the Version 2.0 "Smart EVA" memory cartridge, jump to here.
• If you are using the EVA2 with the Version 3.0 memory cartridge, jump to here.

"Smart" EVA

• Power up the EVA and place the EVA in a location where you have access to the keypad and can see the screen.
• From the main menu, as shown below, press the ENTER key to select "AUTO MODE".

Now go to to the suspected source screen by clicking here.

EVA2

• Power up the EVA and place the EVA in a location where you have access to the keypad and can see the screen.

• From the main menu, as shown below, press the ENTER key to select "AUTO MODE".

then press

Now go to to the suspected source screen by clicking here.

Suspected Source

The "Suspected Source:" screen is displayed next.

Using your mouse, click on the menu option below that you wish to use.

then press

Suspected Source = Engine RPM

Select the number of cylinders in the engine.

then press

Now you must enter the engine RPM that the vibration occurs at.

then press

Next, you select the increment to change the engine RPM with if the RPM selected in the previous step is incorrect.

then press

then press

then press

then press

then press

Finally, the live data screen is displayed.  This screen will show you which component the EVA2 calculates is responsible for the vibration.

As an option, you may press

to display vibration RPM rather than Hz.

• Now go to to the road test procedure by clicking here.

Suspected Source = Vehicle Speed

NOTICE:  In this example, we will use a 4WD Truck.

Select the method of entering the tire information.  In this example, we will use the "Database".

press the down arrow to select "Database"

then press

Next, select the the tire type.  In this example, we will use the "Light Truck".

press the down arrow to select "Light Truck"

then press

Scroll down to find the tire size your vehicle is equipped with.  In this example we will use LT215/85R16D tires.

Scroll the down to the LT215/85R16 tire size with the down arrow.

then press

Next, the Driveshaft Configuration selection screens are displayed.

Press the down arrow to select 4WD

then press

Next, you must select the axle gear ratio of the vehicle.

Use the down arrow key to select 3.73

then press

Next, a confirmation screen appears.  Make sure everything is as you selected.  If it is not, press exit until you return to the screen that needs changing and proceed from there.

Press the Yes Key

Next, you must select the vehicle speed units to display.

For MPH press

Then you must enter the vehicle speed the vibration occurs at.

then press

Next, you select the increment to change the vehicle speed with if the vehicle speed selected in the previous step is incorrect. 

then press

then press

then press

The approximate RPM ranges for each order of vehicle speed related vibrations are displayed next.

then press

then press

Finally, the live data screen is displayed.  This screen will show you which component the EVA2 memory cartridge calculates is responsible for the vibration.

As an option, you may press

to display vibration Hz rather than RPM

• Now go to to the road test procedure by clicking here.

Suspected Source = Help

press the down arrow twice to select "Help"

then press

The Help screen is displayed.

NOTE: The 13002.02-5 book this screen refers the technician to has been out of publication since 2000 and is no longer available.  Click here to use our diagnostic routines instead.

The Road Test

• Road test the vehicle on as smooth and as level of a road as possible.

• A steady throttle must be held in order take accurate readings.

• Road test the vehicle at the speed the vibration is most noticeable.

• Shift the transmission into neutral for several seconds, then back into gear. This procedure may need to be repeated for an accurate diagnosis. If the vibration was not present in neutral, the vehicle has an Engine Speed Related Vibration. If the vibration was still present in neutral, the vehicle has a Vehicle Speed Related Vibration.

• Bring the vehicle back up to the speed where the vibration is most noticeable. Obtain and record a vibration frequency (RPM or Hz) reading from the EVA and a vehicle speed reading. For more information on diagnosing these type of vibrations select Vehicle Speed Related Vibrations.
• If the engine speed or the vehicle speed is different than what the EVA is programmed with, change the speed on the EVA with the up or down arrows.

• Take several measurements at different vehicle speeds to verify the type of vibration.

• If the EVA can match the vibration frequency to a component, it will display that component or components on the screen.  See the two examples below.

In the following example screen, the vehicle speed is 70 MPH. A P1 and a T3 vibration are identified; however the amplitude level is low at 0.07 G's.  This is not a severe vibration.

In the following example screen, the vehicle speed is 45 MPH. A P1 and a T1 vibration are identified; however the amplitude level is very low at 0.03 G's.  This is not a severe vibration.

On Vehicle Diagnosis

• Follow the diagnostics for the type of vibration identified on the road test by clicking here.

This page was last modified Thursday, March 05, 2009 09:02:37 PM

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