Note: See also Section Troubleshooting in the Introduction at the beginning of the Guide.
General information
Ignition/engine control system components are high-reliability components and most failures are usually related to poor contact connections or damaged wiring. Breakdowns in high-voltage wiring most often occur as a result of contamination, moisture or damage to the insulation. Before concluding that a system component has failed, always first check the condition of the corresponding wiring and its contact connections.
Do not check the spark plugs for proper voltage supply by disconnecting the wiring from them and testing it against the engine ground - this type of diagnostics is associated not only with the risk of electric shock, but also with the danger of failure of the ECM or ignition coil. If the stability of the engine speed is disturbed, do not identify the faulty cylinder by successively disconnecting the wiring from the spark plugs.
The following checks help to determine the cause of malfunctions, the symptoms of which are quite obvious (starter failure, misfires, etc.). Some, less obvious, violations may not show themselves due to the automatic transition of the control system to emergency mode of operation and are manifested only in increased fuel consumption, disruption of idle speed stability, reduction in engine efficiency, occurrence of detonations, etc. - contact car service specialists for advice.
The engine does not start
Note: Remember that if the anti-theft device fails, starting the engine is not possible - turn off the immobilizer (see Chapter Controls and operating techniques).
1. If the starter does not turn the engine or turns it too slowly, first check the proper functioning of the starter itself, as well as the condition of the battery. Connect a voltmeter to the battery terminals and measure its output voltage when the starter turns the engine. If the measurement result is less than 9.5 V, you should check the condition of the battery, starter and charging system components.
Caution! Do not activate the starter continuously for more than 10 seconds!
2. If the engine does not start despite the correct rotation of the starter, check the condition of all components of the high-voltage circuit of the ignition system.
3. Following the manufacturer's instructions, connect the stroboscope and crank the engine with the starter - activation of the stroboscope lamp confirms the correct supply of high voltage to the spark plugs. Check the condition of the spark plugs themselves. If the stroboscope does not work, assess the condition of the high voltage wiring (if equipped accordingly - see Chapter Routine care and maintenance). If spark formation is correct, proceed in accordance with the recommendations given in Section Checking and adjusting the ignition timing angle.
4. If there is no spark, make sure the ignition coil(s) are in good condition (the easiest way is to replace the coil with a known good one, - alternatively measure the resistance of the windings). Do not rush to throw away a coil suspected of failure - first make sure of the quality and reliability of its contact connections.
5. Another reason for the failure to start the engine may be a malfunction in the powerful buffer output stage, which is an integral part of the engine control module (ECM), as well as a malfunction of any of the information sensors of the control system, or another associated unit - check the ECM memory for the presence of diagnostic codes (DTC) recorded in it.
Note: DTC codes are read using special diagnostic equipment (see Diagnostics of electronic control systems and diagnostic equipment).
Misfires
1. The most common cause of misfires is poor quality electrical wiring connections on the ignition coil terminals or any of the information sensors.
2. Switch off the ignition and check the corresponding contact connectors for signs of oxidation and reliability of fixation on the terminals.
3. If the kit is complete, check the condition of the high-voltage wiring. Make sure that the wires are securely fastened in all the intermediate clamps provided, make sure that the wires do not come into contact with metal parts of the engine - if a wire with damaged insulation comes into contact with metal, then when the engine is running, sparking will occur not between the contacts of the corresponding spark plug, but at the breakdown point. If even minor damage to the insulation of at least one wire is detected, replace the entire kit.
Note: The easiest way to verify that the high-voltage wiring is in good condition is to replace the entire set with a known good one.
4. To avoid the risk of incorrect connection, replace the spark plug wires one by one.
5. If the electrical wiring is in good condition, the cause of misfiring may be a failure of the spark plug itself or the coil assembly - replace the spark plugs (see Chapter Checking and replacing spark plugs, checking the condition of high-voltage wires), check the condition of the coil. Misfires can also be caused by damage or contamination of the crankshaft position sensor (CKP).
6. If performing the above checks does not reveal the cause of the malfunction, read the DTC codes from the on-board diagnostic module (ECM) memory.