3.5. The car moves jerky

With reference to the car, jerk is a short-term spontaneous change of frequency of rotation of a cranked shaft of the engine irrespective of position of a pedal of "gas". In daily operation series of jerks, as a rule, take place. A limiting case of jerk – a failure, notable delay of response of the engine on pressing of a pedal of an accelerator.

It is conditionally possible to allocate three kinds of jerks:

– At the moment of a start of motion;

– At dispersal;

– At the established movement, i.e. at constant position of a pedal of an accelerator.

For definition of the reasons of jerks at movement of the car with injection the engine the special diagnostic equipment is required, therefore in this case is recommended to address for the car-care centre specialising on repair of systems of injection of fuel. However, as practice shows, in most cases jerks are caused by insufficient pressure of fuel in топливопроводе the engine ("stage") or malfunction of the gauge of position throttle заслонки.

In the presence of some skills the reason of jerks can be revealed independently.

At the moment of a start of motion the limiting case of jerk – a failure is more often takes place. The most unpleasant sensations are connected with delay of response of the engine on pressing of a pedal of "gas". Sometimes the engine thus even глохнет. Jerk arises at the moment of the beginning of opening throttle заслонки when on a signal of the gauge of position throttle заслонки ЭБУ defines the moment of transition from an idling mode on a loading mode and should increase quantity of fuel submitted through atomizers. At insufficient pressure in топливопроводе, even at increase in duration of injection, fuel for smooth трогания from a place does not suffice.

For check of size of pressure of fuel connect to the special union on топливопроводе by means of a piece of a suitable hose a manometre with a limit of measurement of 10 kgs/sm2. At the working engine pressure in топливопроводе should be not less than 3 kgs/sm2.

THE NOTE The union for pressure check has a design similar to the gate of the tyre of a wheel, with a zolotnik. Therefore for connection of a hose of a manometre it is possible to use a tip for a hose foot шинного the pump.

The pressure decrease reasons can be:

– A faulty regulator of pressure of fuel. Besides, regulator refusal can be caused easing of landing of a hose on the union of the vacuum chamber of a regulator;

– The littered fuel filter;

– The faulty fuel pump.

THE NOTE Ways of check and replacement of a regulator of pressure, the fuel filter and the fuel pump see in section 4 "Engine", in подразд. "Power supply system".

The reason of jerks at dispersal can be, the same as and in the previous case (Jerk at the moment of a start of motion »see«), insufficient pressure of fuel in топливопроводе. ЭБУ, having received from the gauge of position throttle заслонки a signal about intensive opening заслонки on the big corner, aspires to increase as much as possible fuel giving, but because of the lowered pressure of fuel not in a condition of it to make. The reasons of this phenomenon and a way of check see «Jerk at the moment of a start of motion».

Such jerks happen are caused by malfunction of system of ignition more often. Diagnostics and repair (section 9 "Electric equipment" see) are necessary. In a way it is possible to try to make independently:

– Attentively to examine подкапотное space. To switch off ignition and to check up reliability of fastening and landing of all wires and sockets at the module of ignition and high-voltage wires. To start up the engine and to listen to its work – a crash at high voltage breakdown «on weight» weak, but distinct. In full darkness it is well visible a spark at breakdown;

– To replace spark plugs irrespective of their condition and run. Pay attention to a condition of candles – if it abnormal, probably, it is necessary to repair the engine or its systems.

Damage of the gauge of position throttle заслонки can be the specific reason of jerks at the established movement of the car with injection the engine. As the additional symptoms confirming malfunction of this gauge serve: – Non-uniform work of the engine idling; – Decrease in the maximum capacity of the engine.

The gauge not folding and consequently неремонтопригоден. If malfunction of the gauge (section 9 "Electric equipment", «the Control system of the engine» see) is revealed, it replace in gathering.