Engine Speed Measurement; Preparation; Placement Of The Speed Sensor - Bosch ETT 223 Operating Instructions Manual

The following numbers of cylinders and engine types are available:
Cylinders 2/4-stroke
1
1
2
2
3
3
4
5
6
8
10
12
1) Default setting
: Numbers of cylinders and engine types
i The setting 4 cylinders / 4-stroke engine must be chosen for
rotary-piston engines.
– Set the number of cylinders and engine type with the setting
switch k ? (4):
- Press the setting switch k ? (4) to the left or right and hold
until the required setting is shown on the LCD display.
i Press to the right → upwards in Table 1.
Press to the left → downwards in Table 1.
– Release the setting switch k ? (4) when the required setting
has been reached.
The display shows the current setting, here 2 cylinders / 2-stroke:
2Cyl/2 2Cyl/2
2Cyl/2 2Cyl/2 2Cyl/2
The module automatically switches to measuring mode after 10
s. The engine speed and signal strength received by the speed
sensor (bar display with 16 segments) are shown on the LCD
display.
Display for engine speed 1000 rpm and maximum signal strength:
2Cyl/2 2Cyl/2 2Cyl/2
2Cyl/2 2Cyl/2
2
4
2
4
2
4
1)
4
4
4
4
4
4
0/min 0/min
0/min 0/min 0/min
1000/min 1000/min 1000/min
1000/min 1000/min

5. Engine speed measurement

5.1 Preparation

– Switch off all electric loads (e.g. heating fan)
– Switch off the air-conditioning system
– Close all vehicle doors
– Start the engine and allow to run at idle speed

5.2 Placement of the speed sensor

Danger of electric shock!
Dangerous voltages occur in the generator network
and in the other electrical systems of motor vehicles.
There is a risk of electric shock if live parts (e.g. ignition
coil) are touched or due to voltage arcs resulting from
damaged insulation (e.g. ignition cables bitten by mar-
tens). This applies to the secondary and primary sides
of the ignition system, the cable harness with plug
connections, light systems (Litronic) as well as the
connections of test devices.
Danger of injury!
Running and stationary engines possess rotating and
moving parts (e.g. belt drives) which can cause injuries
to fingers and arms. In the case of electrically operated
fans in particular, there is a danger that the fan may
switch on unexpectedly when the engine is stopped
and the ignition is switched off.
Danger of burns!
When working on the hot engine, there is a danger of
burns as a result of touching or getting too close to
components such as the exhaust manifold, turbochar-
ger, lambda probe etc. These components can reach
a temperature of several hundred degrees Celsius.
! Position the speed sensor and connecting cable so that they
cannot be damaged by hot or rotating parts (exhaust, fan, belt
pulley etc.).
! The speed sensor must be positioned securely so that it does
not slip due to engine vibrations.
– Set the three-step sensitivity switch for sensitivity adjustment (7)
to the setting –.
– Place the speed sensor (6) in the direct proximity of the engine,
e.g. on the air filter or on the cylinder head cover.
i The speed signal LED (9) will flash quickly (approx. 10 times
per second) if the sensor is positioned correctly.
If the speed signal is not strong enough, the speed signal LED
will flash slowly (approx. once per second).
The signal strength on the LED display should be at least 6
segments.
17