Contents: General information ↡ Preliminary checks ↡
Note: Please also refer to Section Troubleshooting.
The ignition system and the fuel system are interconnected components of the engine management system, so some of its components may also perform certain functions related to the operation of the fuel system.
General information
The ignition system and the fuel system have a common diagnostic system designed to store trouble codes (DTC) and perform diagnostics. When a failure is detected, the control module records the corresponding DTC code in the processor memory, which is a certain sequence of signals that can be read using a special scanner.
Reading the information stored in the ECM processor memory in most cases allows you to determine the causes of engine failures. Analysis of the read information using the code list (see Specifications) allows you to localize the source of failure at the level of a specific element or its electrical wiring circuit.
Attention! Visual inspection of the wiring and connectors is not enough - be sure to read the information stored in the control unit memory!
Preliminary checks
1. If a malfunction occurs shortly after servicing of any unit, first of all, the unit and adjacent components should be carefully examined - it is possible that the cause of the failure is related to an elementary violation of the quality of the contact connection.
2. When searching for the causes of engine malfunction (for example, a drop in the developed power) it always makes sense to check the compression in the cylinders. Make sure that the air and fuel filters are replaced in accordance with the Maintenance Schedule (see Chapter Schedule of current maintenance).
3. Remember that after reading the fault codes and making the appropriate corrections, the control module memory must be cleared.
4. Open the hood and check the reliability of the wire tips on the battery terminals, make sure there are no signs of oxidation of the terminal connections. If necessary, take appropriate measures to eliminate the problem (see Chapter Battery - General information, maintenance recommendations), replace the failed components. Examine the condition of the grounding buses and their terminal connections no less carefully - the contact surfaces of the corresponding mass elements (powertrain/body panels) must be absolutely clean and free from traces of corrosion.
5. Next, carefully inspect all visible electrical wiring laid inside the engine compartment, check the reliability of the contact connections. Replace electrical wiring that shows obvious signs of damage, making sure that the harnesses are laid correctly, and, if necessary, tighten the loose fasteners of the units on which the insulation has rubbed off.
Note: The risk zone is always the areas of electrical wiring that pass near components that have been serviced most recently.
6. It should be remembered that the conductive wires of the electrical wiring may be damaged in the absence of signs of damage to the insulation - in such a situation, an external inspection will not give positive results. Such damage may occur as a result of pulling out the wires, or when the routes of the harnesses are violated.
7. Damaged wiring can be repaired by soldering the shunt core into the broken section - soldering ensures reliable electrical contact. To repair the insulation, use insulating tape or place a piece of heat shrink tubing on the wire. Remember that the best (although not the cheapest) the way to eliminate all failures associated with damage to electrical wiring is to replace the faulty wire.
8. After completing the repair/selecting a replacement, ensure that the appropriate harnesses are routed correctly, paying particular attention to sections of the routes that pass near heated surfaces and moving components in the engine compartment. Ensure that the harnesses are securely fastened to all intermediate fasteners provided.
9. Check the condition of all accessible terminal connections, check the reliability of the fastening of the electrical wiring contact connectors. If traces of corrosion are found on the inner surface of the connector, (white or green deposits/rust coating), and if excessively dirty, remove the connector from the corresponding terminal and clean thoroughly, using a special spray if necessary. Seriously damaged connectors are subject to replacement - in some cases, together with the wiring harness.
10. After cleaning the connector from traces of corrosion, fill it with preservative grease before installing it in place - if necessary, consult with car service specialists.
11. All models covered in this Manual use an inductive crankshaft position (CKP) sensor, which also determines the TDC position of the piston of the first cylinder. Excessive contamination/dust on the sensor may cause misfires. A description of the procedures for removing/installing the CKP sensor is given in Section Removal and installation the crankshaft position sensor (CKP).
12. Carefully inspect the hoses and tubes of all vacuum lines in the engine compartment. Check the tightness of the clamps, make sure there are no deformations, cracks, cuts, delamination or other physical damage to the hoses/tubes. Carefully examine the nipples for signs of leaks. Particular attention should be paid to the condition of the lines laid near sharp edges. Vacuum losses are usually accompanied by a characteristic whistle, upon detection of which the suspected section of the hose should be lubricated with a soap solution - the source of the leak can be considered detected if the stability of the engine speed increases when the solution is applied. Tighten loose clamps, replace damaged lines.
13. Assess the condition and check the patency of the crankcase ventilation hoses - the number of hoses and their installation locations depend on the specific vehicle model, however, all engines use a hose connecting the upper part of the power unit with an intake air tract sleeve or intake manifold. Separate hoses are used to connect to the intake manifold of the cylinder block/oil filler neck - crankcase gases are discharged through them into the combustion chambers of the cylinders. Excessive contamination or obstruction of the ventilation hoses entails a violation of the stability of engine speed, especially idle speed.
14. Moving from the fuel tank to the fuel distribution line (through fuel) filter along the fuel lines, carefully examine the condition of the fuel lines. Pay special attention to the joints of the tubes, where cracks most often form, through which leaks begin to develop. Replace damaged sections of the fuel lines.
15. Remove the air cleaner cover and check the condition of the filter element. An excessively dirty filter can significantly increase the total aerodynamic resistance of the intake air tract, which directly affects the power developed by the engine. Replace the filter element if necessary.
16. Start the engine and let it idle.
Warning! When performing any work in the engine compartment with the engine running, exercise extreme caution - try not to touch the hot surfaces of the power unit and exhaust system, do not allow strands of hair and loose clothing to get into moving components (cooling fan, auxiliary drive belt)!
17. Moving from the air intake to the air cleaner and further to the throttle body, make sure there are no signs of air leaks developing in the intake tract. To identify sources of leaks, you can again use a soap solution. Make the necessary corrections.
18. Drive the car onto a lift and examine the condition of the exhaust system components. Make sure there are no signs of developing leaks - the easiest way to detect leaks in the exhaust tract is to plug its outlet - a characteristic whistle and smoke will help to localize the damaged area. Tighten loose clamps/replace failed sealing gaskets, install a new section(s) in place of the damaged one.
19. At the final stage of the check, start the engine and pull the contact connectors of its electrical wiring one by one - a change in the nature of the engine operation will indicate poor contact quality - make the necessary corrections / replace the faulty sections of the electrical wiring.
20. If, during the preliminary checks, it is not possible to identify the cause of the engine malfunction, the vehicle should be taken to a service station for more thorough diagnostics using special equipment.