Note. See also Section Troubleshooting and to the materials of the Part Diagnostics of electronic control systems and diagnostic equipment.
The ignition system and the fuel system are interrelated components of the engine management system, so some of its components may also perform certain functions related to the functioning of the fuel system.
General information
The ignition system and fuel system have a common diagnostic system designed to store trouble codes (DTC) and performing diagnostics. When a failure is detected, the control module writes to the processor memory the corresponding DTC code, which is a certain sequence of signals that can be read using a special scanner (see part Diagnostics of electronic control systems and diagnostic equipment).
Reading the information stored in the memory of the ECM processor in most cases allows you to determine the causes of failures in the vehicle's engine. Analysis of read information using a list of codes (see Specifications) allows you to localize the source of failure at the level of a particular element, or its electrical wiring circuit.
Attention! A visual check of the wiring and connectors is not enough - be sure to read the information stored in the memory of the control module!
Preliminary checks
If a malfunction occurred shortly after servicing a node, first of all, this node and the components located in the neighborhood should be carefully examined - it is possible that the cause of the failure is associated with an elementary violation of the quality of the contact connection.
When searching for the causes of malfunctioning of the engine (for example, a drop in the developed power) It always makes sense to check the compression in the cylinders. Ensure air and fuel filters are replaced in accordance with the Maintenance Schedule (see chapter Ongoing care and maintenance).
Remember that after reading the trouble codes and making the appropriate corrections, the memory of the control module must be cleared (see part Diagnostics of electronic control systems and diagnostic equipment).
1. Open the hood and check the reliability of fixing the wire ends on the battery terminals, make sure that there are no signs of oxidation of the terminal connections. Perform appropriate troubleshooting steps if necessary (see chapter Ongoing care and maintenance), replace the failed components. No less carefully study the condition of the grounding buses and their terminal connections, - the contact surfaces of the corresponding ground elements (powertrain/body panels) must be absolutely clean and free from signs of corrosion.
2. Next, carefully inspect all visible electrical wiring laid inside the engine compartment, check the reliability of the contact connections. Replace the electrical wiring that has pronounced signs of damage, following the correct laying of the harnesses, if necessary, tighten the loose fasteners of the nodes against which the insulation has frayed.
Note. The risk area is always the wiring that runs close to components that have been serviced most recently.
3. It should be remembered that the conductors of the electrical wiring may be damaged if there are no signs of damage to the insulation - in such a situation, an external examination will not give positive results. Such damage can occur as a result of wires being pulled out, or due to violation of the wiring harness routes.
4. It is possible to restore the damaged electrical wiring by soldering in the area of the shunt wire break, - soldering ensures the reliability of the electrical contact. To repair the insulation, use insulating tape, or put a piece of heat shrink tubing on the wire. Remember that the best (though not the cheapest) The way to eliminate all failures associated with damage to the wiring is to replace the failed wire.
5. After completing the refurbishment / selecting a replacement, monitor the correct routing of the corresponding harnesses, paying special attention to sections of routes passing near heated surfaces and moving components in the engine compartment. Make sure that the harnesses are securely fastened in all provided intermediate clamps.
6. Check the condition of all available terminal connections, check the reliability of fastening of the wiring connectors. If traces of corrosion are detected on the inner surface of the connector (white or green deposits/rust deposits), or if it is excessively dirty, remove the connector from the corresponding terminal and clean thoroughly, if necessary using a special spray. Severely damaged connectors must be replaced, in some cases complete with wiring harness.
7. 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.
8. All models covered in this manual use an inductive crankshaft position sensor (CKP), which also determines the TDC position of the piston of the first cylinder. Excessive dirt/dust on the sensor can cause misfiring. Description of the procedures for removing / installing the CKP sensor is given below in the relevant Sections of this part of the Chapter Engine Electrical Systems.
9. Carefully inspect the hoses and tubes of all vacuum lines in the engine compartment. Check the tightness of the mounting clamps, make sure that there are no deformations, cracks, cuts, delaminations or other physical damage to the hoses / tubes. Carefully examine the choke assemblies for signs of leakage. Particular attention should be paid to the condition of lines laid near sharp edges. Vacuum loss is usually accompanied by a characteristic whistle, upon detection of which the suspect section of the hose should be lubricated with soapy water - the source of the leak can be considered detected if the engine speed stability increases when the solution is applied. Tighten loose clamps, replace damaged lines.
10. Evaluate the condition and check the patency of the hoses of the crankcase ventilation system - the number of hoses and their installation location depends on the specific model of the car, however, on all engines it is used, connecting the upper part of the power unit with an intake air path sleeve, or an intake pipeline. Separate hoses are used to connect to the inlet pipe of the cylinder block / oil filler neck, - through them blow-by gases are discharged into the combustion chambers of the cylinders. Excessive pollution or violation of the patency of the ventilation hoses entails a violation of the stability of the revolutions, especially idle, of the engine.
11. Moving from the fuel tank to the fuel rail (through the fuel) filter along the fuel lines, carefully examine the condition of the fuel lines. Pay special attention to the joints of the pipes, where cracks are most often formed, through which leaks begin to develop. Replace damaged sections of fuel lines.
12. 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.
13. Start the engine and leave it running at idle.
Attention! When performing any work in the engine compartment with the engine running, be extremely careful - try not to touch the heated surfaces of the power unit and the exhaust system, do not allow strands of hair and loose clothing to get into moving components (cooling fan, accessory drive belt)!
14. Moving from the air intake to the air cleaner and further to the throttle body, make sure that there are no signs of the development of air leaks in the intake tract. To identify sources of leaks, you can again use a soapy solution. Make the necessary corrections.
15. Drive the car on a lift and examine the condition of the components of the exhaust system. Make sure that there are no signs of the development of leaks - the easiest way to identify leaks in the exhaust tract is by clogging its outlet, - a characteristic whistle and smoke will help to localize the damaged area. Tighten loose clamps/replace failed gaskets, install a new section to replace the damaged one (And).
16. 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 failed sections of the electrical wiring.
17. If during the preliminary checks it is not possible to identify the cause of the violation of the stability of the engine, the car should be driven to a service station to perform a more thorough diagnosis using special equipment.