Checking work
The ignition distribution sensor is installed on a stand for testing electrical appliances and connected to an electric motor, the rotational speed of which is adjustable. Make connections with the ignition coil, with the switch and the battery in the same way as the ignition system on a car. Four terminals of the cover are connected on the stand with spark gaps, the gap between the electrodes of which is adjustable.
Set a gap of 5 mm between the electrodes of the arresters, turn on the electric motor of the stand and rotate the roller of the sensor-distributor for several minutes counterclockwise (view from the side of the lid) with a frequency of 2000 rpm. Then the gap between the electrodes is increased to 10 mm and they monitor for internal discharges in the distribution sensor, which are detected by sound or by the weakening and interruption of sparking on the arrester of the test stand.
During operation, the ignition distributor should not produce significant noise at any roller speed.
Removing the characteristics of automatic ignition advance
Install the ignition distribution sensor on the stand, connect the output «4» switch with terminal «plus» stand, output «1» with terminal «breaker» stand, output «2» with the body, and the conclusions «3», «5» and «6» switch - with a sensor-distributor ignition.
Turn on the electric motor of the stand and rotate the roller of the ignition distributor with a frequency of 500-600 rpm. According to the graduated disk of the stand, the value in degrees is noted at which one of the four sparks is observed. Increasing the speed in steps by 200-300 rpm, the number of degrees of ignition advance is determined from the disk, corresponding to each speed of the sensor-distributor roller. The obtained characteristic of the centrifugal regulator is compared with the characteristic in fig. 139, a. If the characteristic does not match, then it can be brought back to normal by bending the spring racks.
Pic. 139. Characteristics of centrifugal (A) and vacuum (b) ignition timing regulators of the ignition distributor: A - ignition timing; n - frequency of rotation of the ignition distributor roller; R - rarefaction
To measure the characteristics of the vacuum ignition timing regulator, connect the vacuum regulator fitting to the stand vacuum pump. The electric motor of the stand is turned on and the shaft of the ignition distribution sensor is rotated at a frequency of 1000 rpm. On a graduated disk, a conditional is set «zero» by the moment of sparking in any of the cylinders.
Gradually increasing the vacuum, every 20 mm Hg. Art. note the number of degrees of ignition advance relative to the initial value. The resulting characteristic is compared with the characteristic in Fig. 139.6. Within small limits, you can adjust the characteristic of the vacuum regulator by moving its body. If this method fails to bring the characteristic to normal, then the vacuum regulator is replaced. When taking the characteristic, it is necessary to pay attention to the clarity of return to the initial position after the removal of the vacuum of the base plate of the non-contact sensor.
Checking the proximity sensor
Voltage is removed from the sensor output if there is a steel screen in its gap. If there is no screen in the gap, then the voltage at its output is close to zero.
On the sensor-distributor of ignition removed from the engine, the sensor can be checked according to the diagram shown in fig. 140, a, at a supply voltage of 8-14 V. Slowly rotating the roller of the sensor-distributor, measure the voltage at the output of the sensor with a voltmeter. It should change sharply from the minimum (no more than 0.4 V) to the maximum - no more than 3 V lower supply voltage.
Pic. 140. Schemes for checking the proximity sensor on the removed sensor-distributor (A) and by car (b): 1 - sensor-distributor ignition; 2 - resistor 2 kOhm; 3 - voltmeter with a scale limit of at least 15 V and an internal resistance of at least 100 kOhm
On the car, the sensor can be checked according to the diagram shown in fig. 140.6. An adapter with a voltmeter is connected between the plug connector of the ignition distributor and the connector of the wire bundle. Turning on the ignition and slowly turning the crankshaft with a special key, check the voltage at the sensor output with a voltmeter. It must be within the above limits.