Warning! When performing any maintenance work on system components with the ignition on, special precautions must be observed. Getting an electric shock can have the most serious consequences. Persons with an implanted pacemaker must not perform maintenance on system components. When connecting or disconnecting any components, as well as when using a universal circuit meter to determine electrical resistance, do not forget to turn off the ignition!
Simos static ignition system
On models equipped with the Simos 2P ignition system, where a distributor is not provided, only an extremely narrow range of checks can be performed by the average amateur mechanic.
In the event of any problems associated with a malfunction of the ignition system, always first check the quality of the electrical wiring contact connections on the coil module and the speed and crankshaft position sensor. Also evaluate the condition of the wiring insulation.
Check the fit of the coil module on all spark plugs. Also check the condition of the spark plugs themselves - remember that spark plugs in idle spark ignition systems are subject to increased wear.
Remove the speed and crankshaft position sensor and carefully examine its condition (see Section Removal and installation of information sensors of the ignition system).
If during the above checks it is not possible to identify the cause of the violation, the car should be driven away for a more detailed diagnosis of the ignition system to a Skoda authorized service station.
All other systems
The most common reasons for failures
Most failures of ignition systems are associated with a violation of the quality of the contact connections of the circuit, or with current leaks in the HV circuit. Leaks are usually due to the formation of carbon tracks resulting from electrical breakdowns due to excessive contamination, moisture, or mechanical destruction of components. Before deciding to replace a suspect component, always check the wiring first. Work slowly, methodically checking each of the individual sections of the chain, trying to identify the bad sector by the exception method. In the vast majority of cases, spraying the surface of the components of the system's explosive circuit with a special desiccant such as WD40 helps.
In this case, it is not recommended to check for the presence of a spark in the usual way by bringing the power wire to the engine block, not only because of the increased risk of electric shock, but also in order to avoid failure of the HV coil circuit. you should also not try to identify the cylinder in which misfires occur by disconnecting the wires from each of the candles in turn.
Engine won't start
If the engine does not turn at all, or rotates too slowly, check the condition of the battery and starter. Connect a voltmeter between the battery terminals (with respect to polarity: "+" To "+"; "-" To "-"). Disconnect the ignition coil wire from the BB distributor cap and ground it to a car service workshop. Read the meter reading while cranking the engine with the starter (do not crank the engine continuously for more than 10 seconds). If the measurement is less than 9.5 V, check the condition of the battery and the proper functioning of the starting and charging systems.
If the engine cranks at normal speed, but does not start, check the Ignition HV circuit. Connect a strobe light following the manufacturers instructions, then crank the engine over with the starter. If the strobe flashes properly, then voltage is applied to the spark plugs and the condition of the latter should be checked. If the strobe does not respond to engine cranking, check the condition of the BB wires themselves, then the distributor caps, carbon contact brushes and slider.
If there are no violations in sparking, check the correct functioning of the power system.
The reason for the violation of sparking may be a malfunction in the HB part of the ignition system. Check the 12V power supply to the ignition coil. Assess the condition of the contact connections and electrical wiring. Check the actual coil. The reason for the lack of power to the coil may be a malfunction of the ignition switch, or a blown fuse.
Be aware that a malfunction of the anti-theft alarm system or engine immobilizer may cause the engine to fail to start. Make sure the anti-theft system is properly disabled before continuing with the checks.
If it is not possible to identify the cause of the spark failure during the checks carried out, you should drive the car to a service station to diagnose malfunctions of the engine management system.
There are misfires
Violation of the stability of sparking most often occurs as a result of a violation of the quality of contact connections or the appearance of a non-permanent defect in the LV circuit of the system. The second reason for misfiring is a malfunction of the HV circuit of the system, or damage to the coil side of the runner. In some cases, failures of the speed sensor and crankshaft / Hall position lead to a violation of the stability of the ignition (see Section Removal and installation of information sensors of the ignition system).
With the ignition off, carefully check the external condition of all components of the system, paying special attention to the quality of the contact connections. If you have the necessary equipment at hand, check the condition of the wiring and the quality of the contact connections of the LV ignition circuit.
Make sure the HV ignition coil, distributor cap and HV wires are free from dirt and moisture. By substituting known-good components, check the condition of the explosive wires and spark plugs, then inspect the cover, carbon brushes and distributor runner.
Regular misfires are highly likely to be associated with damage to the distributor cap, BB wires or spark plugs. Use a strobe light to check for BB voltage at the spark plugs.
If there is no HV signal on one of the sections, the cause of the failure is a malfunction of this HV wire or distributor cap. If there is voltage on all the candles, you should check the condition of each of them separately.
The absence of high-voltage voltage on all spark plugs indicates a malfunction of the ignition coil - its secondary winding may be broken as a result of exposure to high electrical loads.
Other violations
If it is not possible to identify the cause of the violation during the above checks, you should seek help from car service specialists..
Check of a condition of components of system of ignition
Note. The information given in this subsection applies only to systems with an ignition distributor.
1. BB state (candlestick) wires should be checked each time the spark plugs are replaced.
2. When disconnecting the wire from the candle, pull only on its tip. Otherwise, there is a risk of damage to the terminals.
Note. Before disconnecting spark plug wires, make sure they have factory markings. If necessary, mark the wires yourself with adhesive tape, inscribing the numbers of the corresponding cylinders on them.
3. Check the inside surface of the wire lug for signs of corrosion in the form of a white powdery coating. Pull the tip firmly over the spark plug shank, making sure it is securely seated. If necessary, disconnect the wire again and correct the position of the contact terminal inside the tip.
4. With a clean rag, carefully wipe the BB wires along their entire length, removing traces of dirt and grease from the insulation surface. After cleaning the wires, check them for burns, cracks, and other damage to the insulation. Avoid excessive bending of the wires to avoid the risk of damaging the strands of the conductor.
5. Disconnect the other end of the wire from its terminal on the cover of the ignition distributor (Again, just pull on the tip!). Check the tip for signs of corrosion. If you have an ohmmeter handy, determine the specific resistive resistance of the wire. Compare the measurement result with the requirements Specifications. When connecting the wire, make sure that the tip is firmly seated on the terminal.
6. Proceeding in a similar manner, check the condition of all explosive wires of the ignition system, including the main one, going from the central terminal on the distributor cap to the ignition coil.
7. Replacement BB wires should be purchased in a kit specially produced for use on cars of this brand.
Distributor cap
1. Release the spring clips and remove the cover from the ignition distributor. Wipe the cover thoroughly and carefully inspect it from the inside and outside for cracks, carbon tracks, burnt contacts and other damage. Assess the degree of wear of the carbon brushes, check their freedom of movement in the holders and the density of pressing against the contact surface of the slider.
2. Do not disconnect all wires from the cover to be replaced at the same time to avoid disturbing the ignition order. Alternately transferring the wires to the terminals of the new cover, firmly fix the latter with the fixing screws / spring clips.
3. When you have finished servicing the system, spray the surface of the components of its HV part with a desiccant.
Distributor slider
1. Remove the distributor cap.
2. Check the external state of the slider. Strictly speaking, it is customary to change the slider in tandem with the distributor cap, regardless of their condition, simultaneously with the installation of new explosive wires, however, due to the fact that on 1.3 liter models the slider is very tightly fitted to the distributor shaft, you should first consult with car service specialists. On 1.6L models, the slider can be easily removed from the shaft
3. Check the condition of the contacts of the slider - one of them is located in the central part of the component and is constantly in contact with the carbon contact of the central terminal of the distributor cover, the second is the working part of the spout, which alternately comes into contact with the segment contacts of the plug wire terminals inside the cover. Using fine-grained sandpaper, clean the contact surfaces, completely removing traces of carbon deposits from them.
4. Installation is carried out in the reverse order. Make sure that the guide ledge of the slider enters the reciprocal recess of the distributor shaft, only after that proceed with the installation of the cover.
Ignition coil
1. Disconnect the HV connector of the ignition coil, and also disconnect the main HV wire of the distributor from it.
2. Connect a universal circuit meter between terminals 1 (1) and 15 (+) (see accompanying illustration) and measure the resistive resistance of the primary winding of the coil. compare the measurement result with the requirements Specifications.
3. Now connect the device between the BB terminal (4) and terminal 15 (+) and measure the resistance of the secondary winding. Compare the result with the one specified in Specifications value.
4. Restore the original wiring connection.
5. If the coil housing is hot to the touch immediately after the engine has stopped, this may indicate damage to the internal insulation.