If the owner of a new vehicle has strictly adhered to the schedule of routine maintenance procedures since the day of its purchase (see Section Schedule of current maintenance of Mitsubishi Galant/Mirage/Diamante cars), performed critical parameter checks frequently enough, maintained the required level of lubricating fluids, the engine will extremely rarely require additional maintenance and repairs (in addition to replacing components and consumables subject to increased wear).
On the other hand, if regular maintenance procedures are performed carelessly and the established inspection schedules are frequently violated, the engine's efficiency will sooner or later inevitably decrease. The likelihood of such a situation occurring is especially high when purchasing a used car. In such cases, it becomes necessary to perform a set of powertrain adjustments beyond the scope of work on the car's current maintenance.
The first step in tuning or diagnosing a poorly performing engine is always to check the cylinder compression pressure (see Chapter Engine), the analysis of the results of which allows you to assess the general condition of the internal components of the engine and outline a plan for upcoming adjustment and / or restoration work. For example, if during the compression pressure test signs of serious internal wear of the engine are detected, the usual set of adjustments will not be enough to correct the situation and its implementation will be a waste of time and money. In view of the value of the information obtained as a result of the compression pressure test, its implementation should be entrusted to a sufficiently experienced and qualified mechanic who has the necessary diagnostic tools.
Below are lists of basic tuning procedures to obtain maximum performance from an engine that is in good mechanical condition.
List of minimum checks and adjustments
Check the levels of all fluids related to engine operation (see Section Checking fluid levels).
Clean and check the battery condition (see Section Checking, servicing and charging the battery).
Check the condition and service the cooling system components (see Section Checking the condition of the cooling system components).
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Check the condition of all hoses located in the engine compartment (see Section Checking the condition and replacing the hoses located in the engine compartment).
Check the condition and proper functioning of the PCV valve (see Section Checking and replacing the crankcase ventilation valve (PCV)).
Check the condition of the air cleaner filter element (see Section Replacing the air cleaner filter element).
Check the condition of the spark plugs (see Section Checking the condition and replacing spark plugs).
Check the condition of the high-voltage wires, cover and distributor rotor (see Chapter Engine electrical equipment).
Check the valve clearances and make adjustments if necessary (see Section Checking and adjusting valve clearances - Mirage only).
Check the idle speed setting and make the appropriate adjustments if necessary (see Chapters Engine и Power and exhaust systems).
Check the ignition timing setting and make the appropriate adjustments if necessary (see Section Checking/adjusting the ignition timing).
Check the condition and tension of the drive belts and make adjustments if necessary (see Section Checking the condition, adjusting the tension force and replacing the drive belts).
List of the full range of checks and adjustments
In addition to the checks listed above:
- Check the condition and proper functioning of the EGR system (see Chapter Engine management systems).
- Replace the PCV valve (see Section Checking and replacing the crankcase ventilation valve (PCV)).
- Replace the air cleaner filter element (see Section Replacing the air cleaner filter element).
- Check the proper functioning of the power supply system and the condition of its components (see Section Checking the condition of the power supply system components).
- Replace the fuel filter (see Section Replacing the fuel filter).
- Replace the high voltage wires, distributor cap and rotor (see Chapter Engine electrical equipment).
- Check the proper functioning of the ignition system and the condition of its components (see Chapter Engine electrical equipment).
- Check the proper functioning of the charging system and the condition of its components (see Chapter Engine electrical equipment).