Contents: Checking the work ↓ Checking the angle of the closed…↓ Removal the vacuum regulator…↓ Insulation resistance testing ↓ Checking the capacitor ↓ Checking the contactless sensor in…↓
Ignition distributor sensor 38.3706-01
1 – ignition distributor sensor shaft; 2 – oil-deflecting clutch of the shaft; 3 – distributor sensor housing; 4 – plug connector; 5 – vacuum regulator housing; 6 – diaphragm; 7 – vacuum regulator cover; 8 – vacuum regulator rod; 9 – support (slave) plate of the ignition timing regulator; 10 – ignition distributor rotor; 11 – side electrode with terminal for wire to spark plug; 12 – distributor cap; 13 – central electrode with terminal for wire from ignition coil; 14 – central electrode carbon; 15 – central contact of the rotor; 16 – 1000 Ohm resistor for suppressing radio interference; 17 – outer rotor contact; 18 – leading plate of the centrifugal regulator; 19 – ignition timing adjuster weight; 20 – screen; 21 – movable (support) plate of the contactless sensor; 22 – contactless sensor; a – groove for distinguishing sensors-distributors 38.3706
Attention! On cars with contactless ignition system the ignition distributor sensor 38.3706-01 is used (see fig. Ignition distributor sensor 38.3706-01).
The contacts must touch with their entire surface. If this does not happen, then by bending the rack bracket, adjust the position of the fixed contact. Do not bend the lever with the movable contact.
Checking the work
1. Before installing the ignition distributor on the stand, check the condition of the breaker contacts, whether the lever with the movable contact is jammed on the axis, and the contact pressing force, which should be 4.9–5.88 N (500–600 gf).
2. Check the wear of the breaker lever's textolite block. If worn, set the required gap between the breaker contacts. If the lever is jammed on the axis or its spring is weakened, replace the contact group.
3. If the breaker contacts are dirty, burnt or eroded, clean them with a velvet file. Sandpaper or other abrasive materials should not be used for this purpose.
4. After cleaning, wipe the breaker contacts with a chamois soaked in gasoline.
5. Then pull the lever to evaporate the gasoline and wipe the contacts again with a dry chamois. You can use any material that does not leave fibers instead of chamois.
6. Wipe off any dirt or oil from the distributor cap.
7. By slightly lifting the distributor cap, check whether the outer contact of the rotor is opposite the electrode of the cap at the moment the breaker contacts open.
8. Install the distributor (or a sensor-distributor) on a test bench for checking electrical ignition devices and connect it to an electric motor whose rotation speed is regulated.
9. Make connections to the ignition coil, battery and switch (for distributor sensor 38.3706-01) similar to the diagram of the car ignition system. Connect the four terminals on the cover on the stand with spark gaps, the gap between the electrodes of which is adjustable.
10. Set a 5 mm gap between the spark gap electrodes, turn on the stand's electric motor and rotate the distributor shaft clockwise for several minutes at a frequency of 2000 min⁻¹.
11. Then increase the gap between the electrodes to 10 mm and watch for internal discharges in the distributor. They are detected by the sound or by the weakening and interruption of sparking on the arrester of the test stand.
12. During operation, the ignition distributor should not produce noise at any shaft rotation speed.
Removing the automatic ignition advance characteristic
Scheme for taking characteristics of the ignition distributor sensor on the stand
1 – switch; 2 – ignition distributor sensor; A – to the "+" terminal of the stand; B – to the "breaker" terminal of the stand
Characteristics of centrifugal (a) and vacuum (b) ignition timing regulators
A – ignition timing angle, degrees;
n – rotation frequency of the ignition distributor shaft, min⁻¹;
P – vacuum, mm Hg.
1. Install the ignition distributor (or a sensor-distributor) on the stand and make electrical connections in accordance with the stand instructions.
2. For the 38.3706-01 ignition distributor sensor, make connections according to the diagram in Fig. Diagram for taking characteristics of the ignition distributor sensor on the stand. Set the gap of 7 mm between the spark gap electrodes.
3. Turn on the stand's electric motor and rotate the ignition distributor shaft at a frequency of 150–200 min⁻¹. On the stand's graduated disk, mark the value in degrees at which one of the four sparks is observed.
4. By increasing the rotation speed stepwise by 200–300 min⁻¹, determine the number of degrees of ignition advance corresponding to the rotation speed of the distributor shaft on the disk. Compare the obtained characteristic of the centrifugal ignition advance regulator with the characteristic in see Fig. Characteristics of the centrifugal (a) and vacuum (b) ignition advance regulators, a.
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Checking the angle of the closed state of contacts
1. Turn on the stand's electric motor and increase the distributor shaft rotation speed to 1000 min⁻¹.
2. Using the illuminated areas of the scale, measure the value of the angle of the closed state of the contacts, which should be 55±3°.
3. Then check the angles between the moments of opening of the contacts on the cylinders relative to the first (asynchronism), which should not differ from the nominal values by more than ±1°.
Removal the vacuum regulator characteristic
1. Connect the vacuum regulator of the ignition distributor with a hose to the vacuum pump of the stand.
2. Turn on the stand's electric motor and rotate the distributor shaft at a frequency of 1000 min⁻¹.
3. Using the graduated disk, set the conditional "zero" for the moment of sparking in any of the cylinders.
4. Smoothly increasing the vacuum, every 20 mm Hg note the number of degrees of ignition advance relative to the initial value. Compare the resulting characteristic with the characteristic in Fig. Characteristics of the centrifugal (a) and vacuum (b) ignition advance regulators, b.
5. Please note the clarity of the return to the original position after removing the vacuum of the movable plate 26 (see Fig. Ignition distributor 30.3706-01) breaker.
Insulation resistance testing
1. The insulation resistance between the high-voltage terminals and ground is checked with a megohmmeter and should be no less than 10 Ohms at (25±5)°C.
2. The resistance between the low-voltage terminal of the breaker and the ground should be the same. It is measured with the breaker contacts open.
Checking the capacitor
The capacitance of the capacitor, measured in the frequency range between 50 and 1000 Hz, should be in the range of 0.20–0.25 μF.
Checking the contactless sensor in the ignition distributor sensor 38.3706-01
Schemes for testing the contactless sensor on a car (a) and on a removed ignition distributor sensor (b)
1 – ignition distributor sensor; 2 – adapter connector with voltmeter; 3 – vehicle wiring harness; 4 – plug connector connected to the ignition distributor sensor; 5 – 2 kOhm resistor; 6 – a voltmeter with a scale limit of at least 15 V and an internal resistance of at least 100 kOhm
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 the sensor output is close to zero.
1. On the car, the sensor can be checked using the diagram shown in Fig. Diagrams for checking the contactless sensor on the car (a) and on the removed ignition distributor sensor (b), a. Between the plug connector of the ignition distributor sensor and the connector of the wiring harness, connect the adapter connector 2 with a voltmeter.
2. Turn on the ignition and, slowly turning the crankshaft with a special key 67.7811.9508, check the voltage at the sensor output with a voltmeter. It should change sharply from the minimum - no more than 0.4 V, to the maximum - no more than 3 V less than the supply voltage.
3. On the ignition distributor sensor removed from the engine, the sensor can be checked according to the diagram in Fig. Diagrams for checking the contactless sensor on the car (a) and on the removed ignition distributor sensor (b) (at a supply voltage of 8–14 V).
4. Slowly rotating the ignition distributor sensor shaft, measure the voltage at the sensor output with a voltmeter. It should be within the limits specified above.