Bosch 3.011 Instructions D'emploi page 31

Number of pulses
The number of pulses used for RPM measurement (engine-speed
measurement) using a clip-on sensor depends upon the type of
engine. The number of pulses must be set accordingly:
- with a 4-stroke engine, 1 pulse
- with a 2-stroke engine, 2 pulses
2.4.2 The TDC sensor
Measuring point
If the vehicle manufacturer has installed a TDC sensor in the
vehicle or there is a hole provided for fixing the workshop TDC
sensor to be used, RPM measurement (engine-speed measu-
rement) can be carried out using this sensor.
- Connect the vehicle-specific TDC-sensor connecting cable to
plug-in socket 3 of the Emission Analysis Measuring Instrument
(see Description of the unit) and to the vehicle.
Number of marks
The number of pulses used for RPM measurement (engine-speed
measurement) using a TDC sensor depends upon the type of
TDC-sensor system.
You must know how many pins or notches there per 360° rotation
of the crankshaft.
2.4.3 The RIV sensor
Measuring point
- Connect the RIV sensor to the injection pump.
- Connect the connecting cable of the RIV sensor to plug-in
socket 2 of the Emission Analysis Measuring Instrument
instead of the clip-on sensor connecting cable (see
Description of the unit).
Number of pulses
The number of pulses used for RPM measurement (engine-speed
measurement) using an RIV sensor depends upon the type of
engine. The number of pulses must be set accordingly:
- for 4-stroke engines: pulse number 1
- for 2-stroke engines: pulse number 2
2.4.4 RPM measurement (engine-speed measurement) by
means of alternator residual ripple (battery connecting
cable B+/B)
The battery connecting cable (B+/B-) is used to measure the
engine speed (RPM) of compression-ignition (diesel) engines
by means of the vehicle electrical system.
Functional description
The engine speed (RPM) is measured by evaluating the residual
ripple of the alternator output voltage. This signal is, however,
superimposed by interference. To be able to detect the useful
signal amongst this interference, an adaptation phase of approx.
15 to 30 seconds is required before the measurement phase.
Measuring procedure
- Switch off the engine.
- Using the battery connecting cable (B+/B-), connect the VSM
(plug-in socket 1, see Description of the unit) to the vehicle
battery. The battery connecting cable is protected against
polarity reversal.
i When working on a 24-V vehicle electrical system, connect
to 24V! Do not connect the VSM just to one of the 2 batteries.
The voltage range is from 9 to 32 V. When working on a
vehicle with a number of independent batteries (e.g. a
camping bus), connect the battery connecting cable (B+/B-) to
the battery that is charged directly by the vehicle alternator.
- Set the number of cylinders accordingly.
- Start the engine and accelerate briefly so that the charge
indicator lamp in the vehicle goes out.
i Switch on the vehicle lights and if fitted the rear heated
window.
Switch off the blower and other consumers.
- Leave the engine running at idle speed.
- The engine speed (RPM) measured can be checked in the
"Engine preconditioning and prechecks" test step.
The engine speed (RPM) measured is displayed after approx.
15 to 30 seconds.
i If RPM measurement (engine-speed measurement) does not
result in a value being displayed, first check whether the
polarity of the connections is correct.
You can now perform a test rev-up.
i The engine must be at normal operating temperature!
When performing the test rev-up, watch the breakaway speed. If
the breakaway speed displayed is plausible and stable,the engine
speed (RPM) measured by means of the alternator's residual
ripple is correct. If not, you must choose a different method of
measuring the engine speed (RPM).
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