Pinpoint Test

PINPOINT TEST A: DRUMMING NOISE 

1. A1 CHECK THE EXHAUST SYSTEM 
   • Key in START position.
   • Increase the engine RPM until the noise is the loudest. Note the engine RPM.
   • Key in OFF position.
   • Add approximately 9 kg (20 lb) of weight to the exhaust system. First place the weight at the tail pipe and test, then at the front pipe.
     Fig 1: Exhaust System

     Courtesy of FORD MOTOR CO.
   • Key in START position.
   • Increase the engine RPM and listen for the drumming noise. Note the engine RPM if the noise occurs.
   • Key in OFF position.
   • Using a vibration analyzer (VA), determine the amount of vibration that occurs with the drumming noise.
   • Is the noise/vibration reduced or eliminated, or does the noise/vibration occur at a different RPM? 
   1. YES  : REFER to Exhaust System Alignment . TEST the system for normal operation.
   2. NO  : CONDUCT a diagnosis on other suspect systems. REFER to NOISE, VIBRATION AND HARSHNESS article.