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5.4.11. Service of system of injection

The majority of the works connected with repair and service of system of injection have to be carried out by experts on STOA. There necessary diagnostic units and the corresponding equipment are available. At malfunctions in electronic control sometimes happens it is necessary to carry out a number of specialized tests to find a cause of defect. Only thus it is possible to define damages of the corresponding knots and details and to avoid more expensive repair. It is independently possible to check malfunctions which arose at violation of operation of the control unit, a condition of sensors, switches and cable connections.

1. Check whether reliably there is a safety lock, whether the relay in sockets and pins is connected.
2. Make sure that the system of heating works regularly.
3. Check a fuel supply system.
4. Make visual survey of system of injection.

Fig. 4.79. Diagnostics of the control unit

5. If it did not bring result, hand over the control unit for check and control of memory.

From the point of view of diagnostics the control unit depends on power setting. At the movement in the store of memory mistakes are accepted, at a stop and shutdown of the accumulator they are removed. The control system of EDS is equipped with an additional source for system of memory, it provides entering in memory even of the insignificant malfunctions arising in a short space of time. By comparison only those malfunctions which need to be eliminated immediately are generally remembered. Memory erases small malfunctions which arise very seldom. "Reading" of these mistakes is possible at the Mercedes station by means of a special tester (NNT) (fig. 4.79). There is also a set of additional characteristics and tests.

    Visual survey of system of injection
"15 000 km"
1. Check air hoses for tightness.
2. Check landing and a condition of a hose of the vacuum amplifier of brakes.
3. Check a condition of hoses of ventilation of a case.
4. Check fuel-supply lines and the correct connection of a fuel-supply line of reverse motion of fuel for tightness.
5. Check all electrosockets and reliability of their connection in an electrical wiring of system of injection.

   Malfunctions of system of switching off of the engine
If the system is faulty or deenergized, the engine will not be switched off. Points out malfunction of system also that the engine is not started at serviceable system of injection and enough fuel.

"15 000 km"
1. Check reliability of connection and a wire to system of switching off of the engine.
2. At turn of the ignition key around knot of switching off the click has to be heard.
3. If there is no click, it speaks about malfunction of power supply or the system.
4. Include ignition and check presence of tension on the system socket.
5. If there is no tension, the cable is faulty or the safety lock is leaky established.
6. If tension is — malfunction of the system of switching off is possible.

   Control of air connections on tightness
At leaky connections so-called foreign air comes to system of absorption or, on the contrary, from system of forcing a part of air passes to atmosphere. It leads to violation of a settlement operating mode and thereof to the wrong dispensing of injection. Leakage of connections is indicated, as a rule, by operation of the engine with interruptions.

"15 000 km"
1. Check the vacuum hoses connected to an inlet collector and system of injection for lack of cuts and damages, and also landing density.
2. Warm up the engine and leave it to work at single turns.
3. From a barrel spray sprinkle fuel flanges of system of absorption, laying of the soaking-up channels, and also pipelines of vacuum lines. If at a sbryzgivaniye of the specified connections the speed of the engine changes, this connection is untight.

   Malfunctions of nozzles
The engine works rigidly, noise of bearings, the ringing sounds is heard, from the muffler there is an exhaust of gray smoke from time to time. At such signs it is necessary consistently, one by one to disconnect the pipelines conducting to nozzles. If at a detachment of one of pipelines there are no changes in operation of the engine, then presumably this nozzle does not work. The refusal of a nozzle can be caused it by pollution. After the long parking of the car the needle of a nozzle can "stick" to the case. At long operation of nozzles pressure of their injection decreases. At stations That is the special device defining suitability of a nozzle. If the nozzle begins work with a pressure below 100 bars, it needs to be replaced.