- when the engine is running, do not touch the elements of the ignition system and do not check their performance «for a spark» between the spark plug wire ends and «weight». This is dangerous for the inspector and may damage the electronic components;
- do not lay low voltage wires of the ignition system in the same bundle with high voltage wires;
- ensure the connection is secure with «weight» switch and controller (in digital ignition system) through the fixing screws. This affects their smooth operation;
- do not disconnect the plug connector from the switch when the ignition is on, as in this case voltage up to 400 V may appear on individual elements of the switch circuit and the switch will be damaged.
Troubleshooting in the ignition system is complicated by the use of electronic components such as a switch and a proximity sensor in the ignition distributor. For the accuracy of diagnosing these nodes, an oscilloscope and a rectangular pulse generator are needed, which the vast majority of motorists do not have. Therefore, below are methods available to motorists for checking ignition system components using the simplest devices: a warning lamp, a home-made indicator and a voltmeter. However, such devices cannot check the shape and parameters of pulses (size and duration), issued by the switch. And they can seriously affect the operation of the engine, especially at high engine speeds. In this regard, an accurate and qualified check of the ignition system can only be carried out at a car service station.
To check the performance of a non-contact sensor, you need an indicator assembled according to the diagram in fig. 116. The indicator uses resistors of the MLT type, 1 W; capacitor C1 - type KLS1, and C2 - type K53-14. As an indicator lamp HL1, an A12 automobile lamp was taken, with a power of up to 3 watts. Instead of a KT816B transistor, you can use a KT814B type transistor. The indicator wires are soldered to a three-terminal block Ш1 of the same type that is connected to the ignition distribution sensor on the car.
The indicator is connected to the ignition distributor sensor instead of the ignition wiring harness. The engine is turned by a starter or a special key for a bolt on a cranked shaft. If the lamp HL1 «flashing», then the proximity sensor is OK.
You can more accurately check the proximity sensor using a voltmeter with a scale limit of at least 15 V and an internal resistance of at least 100 kOhm. Voltmeter 2 (pic. 117) must be included in the adapter between the plug connector of the sensor-distributor and the connector of the bundle of wires going to the switch. Then turn on the ignition and, turning the crankshaft by the pulley mounting bolt, measure the magnitude of the voltage pulses generated by the non-contact sensor. Maximum voltage Umax (see fig. 108,II) must be no more than 3 V less than the supply voltage. Minimum voltage Umin should be no more than 0.4 V.
To test high voltage circuits, a simple spark gap is required from two pointed metal rods, the gap between which can be adjusted. The rods are fixed on a plate of insulating material (plastic or ceramic).
Engine won't start
After making sure that the starter with the battery performs its functions, that fuel enters the carburetor, and the carburetor solenoid valve works when the ignition is turned on, they begin to troubleshoot the ignition system.
First of all, using a lamp of type A12, 3 W, it is necessary to check whether the switch outputs current pulses to the ignition coil. To do this, disconnect the brown wire with red stripes from the ignition coil, going to the terminal «1» switch, and connect the tip of the wire to the lamp. Connect the other end of the lamp to the terminal «+B» ignition coils, turn on the ignition and turn the engine over with the starter. In this case, two cases can be observed.
A) The control lamp is not «flashing». Therefore, the switch does not output current pulses.
Causes of the malfunction and how to fix it:
- a break in the wires connecting the switch to the ignition distribution sensor. Strip wire lugs, replace damaged wires;
- a break in the power supply wires to the switch. Disconnect the block of wires from the switch, connect the tip of the blue wire with the red stripe through the lamp A12, 3 W with «weight» and turn on the ignition. If the lamp does not light, then check the wires and their connections from the terminal «87» ignition relay to terminal «4» switch. Strip wire lugs, replace damaged wires;
- contacts do not close «30/1» and «15/1» ignition switch or contacts «30» and «87» ignition relay. In this case, control devices and direction indicators will not work either. It is necessary to remove the contact part of the ignition switch and check the closure of its contacts, as well as check the ignition relay. Replace damaged contact part or relay;
- break in the primary winding of the ignition coil. To check, disconnect the wires from the ignition coil and connect the clamp through the control lamp A12, 3 W «+B» ignition coils with «a plus» battery, and the other clip with «minus» batteries. If the lamp does not light, then there is a break in the winding. Such an ignition coil must be replaced;
- the roller of the ignition distributor sensor does not rotate due to damage to the roller clutch or loss of the clutch fixing pin. Remove the cover of the ignition distributor and, turning the engine with a starter, check whether the roller rotates. If the roller does not rotate, then remove the ignition distributor and replace the damaged parts;
- contactless sensor defective. Disconnect the wiring block from the ignition distributor and connect the indicator assembled according to fig. 116, or adapter with voltmeter (see fig. 117) Switch on the ignition and turn the engine crankshaft. If the lamp is not «flashing» or the magnitude of the voltage pulses measured by the voltmeter is not correct, then replace the proximity sensor or the ignition distribution sensor;
- switch is faulty. If previous checks have shown that the wires and the ignition distributor are OK, then, therefore, the switch is faulty and must be replaced.
b) Pilot lamp «flashing». Therefore, the low voltage circuit of the ignition system is OK, and the fault must be sought in the high voltage circuits.
First of all, you need to inspect the wires and ignition devices. They must be dry and clean. After washing the car or overcoming the ford, there may be moisture on the wires and devices of the ignition system, as well as inside the cover and on the rotor of the ignition distributor, which makes it very difficult to start the engine. Therefore, they must be wiped dry with clean suede or other material that does not leave fibers. Remove the ignition distributor cover, wipe it inside, as well as the rotor. After making sure that all wires and devices are dry and clean, it is necessary to disconnect the wire tip from any spark plug and connect it to the arrester electrode. Connect the second electrode of the spark gap to «mass» car and set the air gap between the electrodes of the arrester 7... 10 mm. Turn the engine crankshaft with the starter. In this case, two cases can be observed.
A) The spark is strong and breaks through the gap.
Causes of the malfunction and how to fix it:
- the order of connecting high-voltage wires to the sockets of the cover of the ignition sensor-distributor is violated. Check and connect the wires in accordance with the order of operation of the engine cylinders 1-3-4-2;
- the high voltage wires are loose or loose. Check the wires and the reliability of their connection to the spark plugs and the ignition distribution sensor, replace the damaged wires;
- incorrect ignition timing. Check and adjust the ignition timing;
- the gap between the electrodes of the spark plugs is not correct or the spark plugs are oily. Clean the spark plugs and adjust the gap between the electrodes. The gap should be 0.7...0.8 mm. It is checked with a round wire probe. It is impossible to check the gap with a flat probe, since this does not take into account the recess on the side electrode, which is formed during the operation of the candle. The gap is adjusted by bending only the side electrode of the spark plug. It is not allowed to bend the central electrode, as this can cause breakage of the ceramic insulator;
- damaged spark plugs (cracks in the insulator, burnout of the spark plug electrodes). Inspect spark plugs, replace damaged ones with new ones.
b) There is no spark.
Causes of the malfunction and how to fix it:
- current leakage through cracks or burnouts in the cover or rotor of the ignition distributor sensor, wear, damage or freezing of the carbon electrode in the cover of the ignition distributor sensor. In this case, there is no spark when all spark plug wires are connected to the spark gap, while when the central wire is connected to the spark gap, the neoplasm is normal. Check the cover and rotor of the ignition distributor, the condition of the carbon electrode. Replace damaged parts;
- break in the secondary winding or internal discharges in the ignition coil. When connecting a high voltage wire from the ignition coil to the arrester, there is no sparking. Replace ignition coil.
Engine runs erratically or stalls at idle
The malfunction manifests itself in an uneven exhaust sound and sudden engine stops at idle. Causes of the malfunction and how to fix it:
- too early ignition in the engine cylinders. Check, if necessary, adjust the ignition timing;
- large gap between the electrodes of the spark plugs. Check and adjust the gap between the electrodes of the spark plugs.
The engine runs unevenly and unstably at a high crankshaft speed
The cause of the malfunction is the weakening of the springs of the weights of the ignition timing regulator in the ignition distributor sensor. This cause of the malfunction can only be detected at a car service station by checking the characteristic of the centrifugal ignition timing controller at the stand.
Interruptions in the operation of the engine in all modes
The malfunction manifests itself in an uneven exhaust sound and a decrease in engine power both at low crankshaft speed and at high speed.
Causes of the malfunction and how to fix it:
- the wires in the ignition system are damaged, the fastening of the wires is loosened or their tips are oxidized; the interference suppression tips of the high voltage wires are damaged. Inspect the wires, their connections, replace damaged wires. Check high voltage wires with a spark gap as described above;
- oiling, soot or damage to the spark plug. A faulty spark plug can be detected by disconnecting the wires from the spark plugs one by one and starting the engine. If, after disconnecting the wire, engine interruptions increase (or it won't start at all), then this spark plug is good. If the idle spark plug is disconnected, the interruptions in the operation of the engine will remain unchanged. In addition, a faulty spark plug can also be found by the temperature of the insulator after the engine has stopped. At an idle candle, it will be noticeably colder than at a working one. Remove the faulty spark plug, clean and adjust the gap between the electrodes. damaged candle (with cracks in the insulator, burnt out electrodes) replace;
- cracks, dirt or burnouts in the rotor or cover of the ignition distributor sensor, inspect it and the rotor, clean it from dirt and moisture, replace the damaged cover and rotor;
- wear or damage to the carbon electrode in the cover of the ignition distributor sensor, weakening of the spring of this electrode, severe burning of the central contact of the ignition sensor rotor rotor. Check if the carbon electrode is broken and if it moves easily in its socket, clean the central contact of the rotor. In case of damage or wear of the carbon electrode, replace the cover of the ignition distributor;
- the switch is faulty - the shape of the pulses on the primary winding of the ignition coil does not correspond to the norm. This fault must be checked at a service station. Replace defective switch.
The engine does not develop full power and does not have sufficient throttle response
This malfunction manifests itself in a decrease in the speed of movement and slow acceleration of the car.
Causes of the malfunction and how to fix it:
- incorrect ignition timing. Check and adjust the ignition timing;
- jamming of the weights of the ignition timing regulator in the ignition distributor, weakening of the weights springs. It is necessary to contact a service station to check the characteristics of the centrifugal ignition timing controller;
- the switch is faulty - the shape of the pulses on the primary winding of the ignition coil does not correspond to the norm. Check the switch at a service station, replace the faulty switch.