Dacia Pick-Up 1304/1305/1307. Service manual - part 37

IGNITION AND  INJECTION

17

17 - 12

From now on, we can calculate the injection time (t

i

), the injection moment and the

ignition advance moment for each engine cycle.

The rotation sensor is fixed on the clutch case of the gearbox therefore it should be at 1

± 0,5 mm from the teeth peak of the flywheel.

The connector for the rotation sensor has the following connections (drawing 8):

1,2 – capture of rotation signal
3 – screening

The sensor functioning can be checked by connecting the connector pins 1 and 2 or the

computer pins 3 and 21 to an oscilloscope. A good sensor will generate a signal shaped as
in drawing 8, during the engine functioning, in which we can identify the following:

A = gear toothed area (rotation signal)
B = the 2 missing teeth area
C = the first tooth area (reference signal)

The rotation sensor is not to be repaired but replaced.

Fig. 8

Fig.9

The rotation signal level should be Uss > 2,5 V, otherwise the engine won’t start.
The reference value R

1-2

 = 650 – 1100 Ù at an environmental temperature of 20°C.

DESCRIPTION OF THE SYSTEM

17

IGNITION AND  INJECTION

17 - 13

ENGINE TEMPERATURE SENSOR

The engine sensor T is an NTC type (negative temperature coefficient); its internal

resistance will decrease with the increasing of the temperature.

It is checked with an ohmmeter connected to the sensor terminals or even better with a

voltmeter, during the engine running The voltage of the cold engine should be U = 5 V;
this voltage decreases according to the heating of the engine. In case there is a short circuit
the voltage will drop, first slowly, then suddenly. This is a very precise diagnosis as it is
done under running.

The engine sensor T is not to be repaired but replaced.

Reference values:      R sensor = 1450 - 3300 

Ω la 15 - 30 

0

 C

   R sensor = 2500 +/- 125 

Ω la 20 

0

 C

The report between the sensor resistance and the temperature is:

T [

 0

 ]

- 10

   0

   10

  20

 40

 60

 80

100

R [ 

Ω ]

9200 5900 3700 2500 1180 600

325

190

DESCRIPTION OF THE SYSTEM

IGNITION AND  INJECTION

17

17 - 14

 INDUCTION COIL

The induction coil is a double-coil with stationary distribution of the voltage without

moving elements. The voltage in the secondary circuit of the coil can reach 30 KV, the
distance between the spark plugs electrodes should be 0,8 mm and the spark plugs wires
should have a special construction according the new concept of anti-electric interference.

When the engine is on contact the coil is supplied with a (+ DC) voltage; it is controlled

by the electronic control unit (-), as follows:

- for spark plugs 1 and 4 – pin 1;
- for spark plugs 2 and 3 – pin 19.

The secondary circuit is closed by the two spark plugs; the spark voltage at the cylinder

under compression is about 20 KV; the auxiliary voltage at the cylinder under evacuation
is 250 – 300 V, reversed polarity.

DESCRIPTION OF THE SYSTEM

17

IGNITION AND  INJECTION

17 - 15

EXAMPLE

:

- piston 4 at compression = ignition spark; about 20 KV (drawing 10).
- piston 1 evacuation = auxiliary spark; about 300 V (drawing 11).

The two voltages can be viewed through an oscilloscope and an adapter.

Fig. 10

Fig.11

The reference values, measured at the ignition coil connector are as follows:

- for secondary windings: R

1-4 

= R

1-3

 = 10 – 16 KÙ

 at 20°C

- for primary windings: R

1-2 

= R

3-4

 = 0.4 – 0.6 Ù

 at 20°C

The reference values for spark plugs wires:
R = 3000 – 7000 Ù 

at an environmental temperature of 20°C

DESCRIPTION OF THE SYSTEM