Mercedes M-Class W163

since 1997 release

Repair and operation of the car

Checks of a control system of ignition and injection

See also Section Diagnostics of Malfunctions in Introduction at the beginning of the Management.

General information

Components of systems of ignition/management of the engine are among elements of the increased reliability and the majority of refusals, as a rule, are connected with violation of quality of contact connections or damage of an electrical wiring. Breakdowns of VV of an electrical wiring most often happen in a consequence of pollution, moistening or damage of isolation. Before coming to conclusion about failure of a component of system, always first of all check a condition of the corresponding electrical wiring and its contact connections.

You do not make check of serviceability of giving of tension on spark plugs by a detachment from them of an electrical wiring and its approbation on the mass of the engine, - such diagnostics is accompanied not only by risk receiving an electroshock, but also by danger of failure of ECM or the coil of ignition. At violation of stability of working turns of the engine it is also not necessary to make identification of the faulty cylinder by a consecutive detachment of an electrical wiring from spark plugs.

The listed below checks allow to define the reason of malfunctions which symptoms are rather obvious (refusal of a starter, admissions of ignition, etc.). Some, less obvious, violations can not show themselves due to automatic transition of a control system to emergency operation of functioning and are shown only in increase in fuel consumption, violation of stability of turns of idling, to reduction of efficiency of return of the engine, emergence of detonations and so forth, - address for consultations specialists of car service.

The engine is not started

Remember that at failure of the anti-theft device start of the engine is not possible, - disconnect an immobilizer (see the Head Governing bodies and methods of operation).

PERFORMANCE ORDER

If the starter does not turn the engine, or rotates it too slowly, first of all check serviceability of functioning actually of a starter, and also a condition of the rechargeable battery. Connect the voltmeter to plugs of the battery and measure its output tension at an engine provorachivaniye by a starter. If the result of measurement makes less than 9.5 In, it is necessary to check serviceability of a condition of the battery, a starter and components of system of a charge. Do not activate a starter continuously more than within 10 seconds! If the engine is not started despite serviceability of rotation of a starter, check a condition of all VV components of a contour of system of ignition. Working strictly according to instructions of the manufacturer, connect a stroboscope and turn the engine a starter, - activation of a lamp of a stroboscope confirms serviceability of giving of VV of tension on spark plugs. Check a condition actually of candles. If the stroboscope does not work, estimate an electrical wiring VV condition (at the corresponding complete set, - see the Head the Current leaving and service). At correct sparking act according to the recommendations provided in the Section Check and adjustment of a corner of an advancing of ignition. In the absence of sparking make sure of serviceability of the coil(s) of ignition (simplest to replace the coil obviously serviceable, - alternatively to measure resistance of windings). You do not hurry to throw out the coil suspected of refusal, - before make sure of quality and reliability of its contact connections. Violation in the powerful buffer output cascade which is a component of the module of management of the engine (ECM) and also malfunction of any of information sensors of a control system, or other accompanying knot can be one more cause of failure of start of the engine, - check memory of ECM for existence of the diagnostic codes (DTC) which are written down in it. Reading of the DTC codes is made by means of the special diagnostic equipment (see Diagnostics of systems of electronic control and the diagnostic equipment).

Admissions of ignition

PERFORMANCE ORDER

Most often violation of quality of contact connections of an electrical wiring on plugs of coils of ignition or any of information sensors is the reason of admissions of ignition. Switch off ignition and check the corresponding contact sockets for existence of signs of oxidation and reliability of fixing on plugs. At the corresponding complete set believe a condition of VV of an electrical wiring. Make sure of reliability of fixing of wires in all provided intermediate clamps, be convinced that wires do not adjoin to metal parts of the engine, - if the wire with the broken isolation concerns metal, then during the operation of the engine sparking will take place not between contacts of the corresponding spark plug, and in the place of breakdown. At identification even of insignificant damage of isolation at least of one wire replace all set. It is the simplest to make sure of serviceability of a condition of VV of an electrical wiring by replacement of all set by obviously serviceable. In order to avoid risk of violation of correctness of connection, you make replacement of candle wires serially. At a serviceable electrical wiring failure actually of a candle, or bobbin assembly can be the reason of admissions of ignition, - replace candles (see the Head of the Power supply system and production of the fulfilled gases), check a condition of the coil. Also damage or pollution of the sensor of position of the crankshaft (CKP) can be the cause of admissions of ignition. If performance of the listed above checks does not allow to establish a cause of infringement, make reading of the DTC codes from memory of the module of onboard self-diagnostics (ECM).