Mercedes M-Class W163

since 1997 release

Repair and operation of the car

Search of malfunctions - the general information and preliminary checks

Address also the Section Diagnostics of Malfunctions.

The system of ignition and fuel system are the interconnected components of a control system of the engine therefore some of its components can perform also certain functions concerning functioning of fuel system.

General information

The system of ignition and fuel system have the general diagnostic system intended for preservation of codes of malfunctions (DTC) and performing diagnostics. At refusal identification the module of management writes down in the processor memory the corresponding DTC code representing some sequence of signals which can be a schitana by means of the special scanner.

Reading of information which is stored in the processor memory of ECM in most cases allows to define the reasons of failures in operation of the engine of the car. The analysis of only a few information with application of the list of codes (see Specifications) allows to localize a refusal source at the level of a concrete element, or a chain of its electrical wiring.

Visual check of an electrical wiring and sockets is not enough - surely consider information which is stored in memory of the control unit!

Preliminary checks

PERFORMANCE ORDER

If malfunction arose soon after performance of service of any knot, first of all it is necessary to investigate carefully this knot and components located in the neighbourhood, - is not excluded that the cause of failure is connected with elementary violation of quality of contact connection. When carrying out searches of causes of infringement of serviceability of functioning of the engine (for example, falling of the developed power) always it makes sense to check a compression in cylinders. You watch that replacement of air and fuel filters was made according to the Schedule of maintenance (see the Head of the Power supply system and production of the fulfilled gases). Remember that after reading of codes of malfunctions and introduction of the corresponding corrections memory of the module of management has to be cleared. Open a cowl and check reliability of fixing of tips of wires on polar plugs of the battery, make sure of lack of signs of oxidation of terminal connections. In case of need make the appropriate measures on debugging (see the Head of the Power supply system and production of the fulfilled gases), replace the failed components. Study a condition of tires of grounding and their terminal connections not less attentively, - contact surfaces of the corresponding elements of weight (the power unit / body panels) have to be absolutely pure and free from corrosion traces. Further, attentively examine all visible electrical wiring laid in a motive compartment, check reliability of contact connections. Replace the electrical wiring having pronounced signs of damage, having tracked correctness of laying of plaits, in case of need tighten the weakened fixture of knots about which isolation frayed. Risk zone are always the sites of an electrical wiring passing near components which service was made in the most recent time. It is necessary to remember that conducting veins of an electrical wiring can be damaged in the absence of isolation damage signs, - in a similar situation external survey will not yield positive results. Similar damages can result from a pulling of wires, or at violation of routes of laying of plaits. It is possible to restore the damaged electrical wiring by a vpaivaniye on the site of break of the shunting vein, - the soldering provides reliability of electric contact. For repair of isolation use an insulating tape, or put a piece of a thermoshrinkable tube on a wire. Remember that the best (though not the cheapest) way of elimination of all refusals interfaced to damage of an electrical wiring is replacement of the failed wire. Having finished recovery repair / having picked up replacement, track correctness of laying of the corresponding plaits, paying special attention to the sites of routes passing near the warmed surfaces and moving components in a motive compartment. Track reliability of fixing of plaits in all provided intermediate clamps. Check a condition of all available terminal connections, check reliability of fastening of contact sockets of an electrical wiring. At identification on the internal surface of the socket of traces of corrosion (white or green deposits / a rust raid), and also at excessive pollution, remove the socket from the corresponding plug and carefully clear, having in case of need used special spray. Seriously damaged sockets are subject to replacement, - in certain cases in a set with an electrical wiring plait. After cleaning of the socket of traces of corrosion fill it before installation to the place of the preserving lubricant, - in case of need consult with specialists of car service. On all models considered in the present manual the inductive sensor of provision of a bent shaft (CKP) by means of which also the provision of VMT of the piston of the first cylinder is defined is used. Excessive pollution / запыление the sensor can be the reason of admissions of ignition. The description of procedures of removal/installation of the CKP sensor is provided in the Section Removal and installation of the sensor of provision of a bent shaft (CKP). Attentively examine hoses and tubes of all vacuum lines of a motive compartment. Check reliability of tightening of fixing collars, make sure of lack of deformations, cracks, cuts, stratifications and other physical damages of hoses/tubes. Attentively study nipple knots on existence of signs of violation of tightness. Special attention should be paid to a condition of the lines laid near keen edges. Depression losses usually are followed by characteristic whistle at which identification the suspected site of a hose should be greased with soap solution, - the source of leak can be considered found if when putting solution stability of turns of the engine increases. Tighten the weakened collars, replace the damaged lines. Estimate a condition and check passability of hoses of system of ventilation of a case, - the quantity of hoses and the place of their installation depends on concrete model of the car, nevertheless, on all engines is used, connecting the top part of the power unit a sleeve of an inlet air path, or the inlet pipeline. Separate hoses are applied to connection with the inlet pipeline of the block of cylinders / маслозаливной mouths, - on them crankcase gases are taken away in combustion chambers of cylinders. Excessive pollution or violation of passability of ventilating hoses involves violation of stability of turns, - especially single, - the engine. Moving from the fuel tank to the fuel distributive highway (through fuel) the filter along fuel pipelines, attentively study a condition of fuel lines. Pay special attention to places of a joint of tubes where cracks through which leaks begin to develop are most often formed. Replace the damaged sections of fuel lines. Uncover the air cleaner and check a condition of the filtering element. Excessively polluted filter is capable to increase considerably the total aerodynamic resistance of an inlet air path that directly affects the power developed by the engine. In case of need replace the filtering element. Start the engine and leave it working at single turns. When performing any works in a motive compartment at the working engine observe extreme care, - try not to touch the warmed surfaces of the power unit and system of production of the fulfilled gases, do not allow hit of locks of hair and free elements of clothes in moving components (the cooling system fan, a belt of the drive of auxiliary units)! Moving from an air inlet to the air cleaner and further - to the throttle case, make sure of lack of signs of development of leak of air in the inlet highway. For identification of sources of leaks it is possible to use soap solution again. Make necessary corrections. Tire out the car on the elevator and study a condition of components of system of production of the fulfilled gases. Make sure of lack of signs of development of leaks, - it is the simplest to reveal thinnesses of a final path it is possible by a blockage of its exhaust outlet, - characteristic whistle and smoke will help to localize the damaged site. Tighten the weakened collars / replace the failed sealing laying, establish instead of damaged new section(s). At the final stage of check start the engine and serially pull contact sockets of its electrical wiring, - change of kind of work of the engine will testify to bad quality of contact, - make necessary corrections / replace the failed sites of an electrical wiring. If during conducting preliminary checks it is not possible to identify a cause of infringement of stability of operation of the engine, the car should be driven away on the station of service for performance of more careful diagnostics with use of the special equipment.