Neutral Engine Run-Up (NERU) Test

To carry out this test, proceed as follows:
^ Install a tachometer.
^ 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.
^ Attempt to identify what part of the vehicle the concern is coming from.
^ Attempt to identify the source of the concern.
^ Proceed as necessary.