Note: Exhaust Noise Inspector Type 3638 A/B does not determine if the external tachome-
ter's settings are correct. Once Type 3638 A/B is turned on, it is ready to start measurement
procedures.
5) Exhaust Noise Inspector Type 3638 A/B automatically detects the connection to the ta-
chometer (but not the tachometer setup). On Type 3638 A/B system controller, go through
the measurement setup parameters – see "Setup" on page 19 for instructions:
6) When all setup parameters are configured, press OK to start a measurement. The system
controller display reading shows Waiting....
7) Start the vehicle engine. Monitor Tachometer Type 2979 to see if its display flashes 'R'. If
there is no 'R' or the display only shows '-----', stop the engine, re-position the tachom-
eter, either closer to or further away from the spark plug leads and start the engine again.
8) The system controller display will show the real-time RPM value (engine speed) as soon as
noise from the exhaust is detected.
9) Operate the throttle so that the engine speed gradually increases from idle to the trigger
RPM value. The RPM Indicator LEDs can be a big help in indicating when the trigger
level is reached.
a) If the measured RPM is below the predefined RPM value range – the left red LED
lights.
b) If the measured RPM is above the predefined RPM value range – the right red LED
lights.
c) If the measured RPM is within the predefined RPM value range – the middle green
LED lights.
10) When the green LED lights, hold that speed constant from 1 to 6 seconds (see "Run-up
Time Setting" on page 13 for setting of this system parameter). This constant RPM value
will trigger the measurement of sound levels and the following will occur:
•
Type 3638 A/B's display shows sound levels instead of RPM and remaining measure-
ment time.
•
The green LED begins flashing, which indicates that sound level measurement is in
progress.
Measuring
1: 94.0 dB(A); 2 s
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PART 1
31
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