Vaz 21213, Руководство по ремонту, Страница: 156 / 222

Resistance of the insulation to earth should be at least 50
MOhm.
Spark control module
The spark control module can be tested using an oscilloscope
and square wave pulse generator connected as shown in Fig.7-
25. The pulse generator resistance should be 100-500 Ohm. It is
preferable to use a double-channel oscilloscope - the 1st channel
is for the generator pulses, while the 2nd channel - for the control
module pulses.
Square wave pulses, simulating those of the distributor sen-
sor, are supplied to the module terminals 3 and 6. The pulse fre-
quency should be within 3.33 - 233 Hz, while the duty cycle (peri-
od-to-pulse length ratio, í/íË) should be set to 3. The maximum
voltage (Umax) is 10 volts, the minimum voltage (Umin) should
not exceed 0.4 volts (Fig.7-26, II). A sound control module should
generate the pulses as shown in oscillogram I.
For 3620.3734 and 76.3734 modules at the supply voltage
13.5±0.5 volts, the current flow (Ç) should be from 7.5 to 8.5
amps. There is no standard dwell (current saturation) (Ä) .
For RT1903 module at the supply voltage of 13.5±0.2 volts
and frequency of 25 Hz, the current flow is 7 to 8 amps, while the
dwell is 5.5 to 11.5 milliseconds.
For PZE4022 module at the supply voltage of (14±0.3) volts
and frequency 25 Hz, the current flow is 7.3-7.7 amps, while the
dwell is not specified.
For ä563.3747 module at the supply voltage of (13.5±0.5)
volts and frequency 33.3 Hz, the current flow is 7.3-7.7 amps,
while the dwell is not specified.
Any distortions in the pulse waveform can result in misfires or
retarded ignition. The engine will tend to overheating and will not
develop maximum power.
Spark plugs
If the spark plugs are foul or have deposits, then prior to test-
ing clean them by means of a sand blasting machine and blow
with compressed air. When the insulator nose is covered with
light tan to greyish brown deposits, there is no need to clean
them, as it is indicative that the mixture is correct and the engine
is in good condition.
Once the plugs have been cleaned, examine them and set
the correct spark gap. If the insulator is chipped, cracked or the
side electrode weld is perished, renew the spark plug.
Check the spark plug gap (it is to be 0.7-0.8 mm) with a round
wire feeler blade. It is not recommended to use a flat feeler blade
since it is cannot account for erosion (cut-out) on the outer electrode
which appears in course of operation. Bend, open or close, the
outer (side) plug electrode only until the correct gap is achieved.
Leak test.
Screw the plug into the seat on the tester and
tighten it to a torque of 31.4-39.2 N•m (3.2-4 kgf•m). Build up the
pressure of 2 åPa (20 kgf/cm
2
) in the tester chamber.
Take an oil cup and place a few drops of oil or kerosine on
the spark plug; the broken tightness is evident through the air
bubbles between the insulator nose and metal plug body.
Electrical test.
Insert the spark plug to the seat on the tester
and tighten to the torque specified above. Adjust the gap between
the spark box electrodes to 12 mm, which corresponds to 18
kvolts; afterwards, using a pump, build the pressure up to 0.6
åPa (6 kgf/cm
2
).
Fit the end of the HT cable to the plug and apply HT pulses.
The spark plug is sound when a good spark is observed
through the tester sight window. When sparking takes place
between the spark box electrodes, decrease the pressure in the
tester. Next recheck the pressure value when the spark jumps
between the spark plug electrodes.
154
Fig.7-26. Displaying pulse waveform at the oscilloscope:
I - control module pulses; II - alternator pulses; Ä - dwell (current saturation
time); Ç - maximum current; í - pulse period; íË - pulse width
Fig.7-25. Checking the spark control module:
1 - spark gap; 2 - ignition coil; 3 - control module; 4 - 0.01 Ohm resistor (1%, at
least 20 W); Ä - to square wave generator; Ç - to oscilloscope