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6.3.1 Number of pulses and type of ignition
During engine-speed measurement, the number of pulses for 2
revolutions of the crankshaft (720°) is evaluated. These pulses
can be secondary signals (ignition pulses), primary signals (term.
1 o term 15 pulses /currents or voltages) but also pulses
(voltages) that supply a signal that corresponds to the engine
speed (e.g.: TD or TN signal).
It is therefore necessary to set the number of pulses.
Possible pulse rates are: 1, 2, 3, 4, 5, 6, 8, 10, 12 and 16.
The pulse rate present in the type of vehicle being tested must be
taken from the table below and set at the exhaust-gas analyser.
Ignition system Engine
EST
ROV
4T
ROV
2T/Wankel
2x ROV
4T
EFS
4T
EFS
2T/Wankel
EFS with NW
4T
EFS with NW
2T/Wankel
DFS
4T
DFS
2T/Wankel
Z = No. of cylinders, ROV = Rotating high-tension distribution, EFS = Single-spark coil, DFS = Dual-spark coil, NW = camshaft
16
Trigger clamp.on pickup
Setting the pulse rate on ETT (see section 6.3)
Measuring point in accordance with figures below
Item 3, 4
Item 5
Term. 1/15
Term. 1/15
one ignition
common cable of
circuit
all ign.circuit
Z
Z
2 x Z
2 x Z
Z/2
Z/2
2
Z
4
2xZ
1
Z
2
2 x Z
2
Z
4
2 x Z
The number of pulses per 720° revolution of the crankshaft
depends on various factors:
– Type of engine
4-stroke, 2-stroke or rotary piston (Wankel)
– No. of cylinders
1, 2, 3, 4, 5, 6, 8, 10, 12
– Type of ignition
Rotating ignition distribution with one igniti-
on distributor (ROV)
Rotating ignition distribution with two igniti-
on distributors (2x ROV)
Ignition system with single-spark coil and
crankshaft sensor (EFS)
Ignition system with single-spark coil,
crankshaft and camshaft sensor (EFS with
NW)
Ignition system with dual-spark coils (DFS)
– Measuring point see section 6.2.5
Item 6
Item1
Item 2
Spark-plug cable
Cable from
coil to
distributor
-
1
-
2
2 x Z
-
1
Z/2
2
-
4
-
-
1
-
2
2
-
4
-
Connecting cable
Term.1, TD/TN, EST und B-
Item 3
no figure
Term. 1 of
Control signals
an ign.Circuit e.g. TN, TD,
Z
Z
2 x Z
Z/2
-
2
-
4
-
1
-
2
-
2
-
4
Z
Z
Z
Z
Z
Z
Z
Z
Z
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