Citroën Xantia

since 1993 release

Repair and operation of the car

Systems of injection of fuel - the general information

In systems of injection of fuel the electronic control unit (ECU) of the self-adjusted type is used. In the course of functioning of ECU traces and keeps in the memories of installation allowing to receive the maximum return from the engine. At a battery detachment all introduced installations are erased and ECU reverts to the original state with the basic parameters entered into the memory block at manufacturer. In view of told at primary start after connection of the battery the engine for some time can unstably work. Process of an exit of ECU in the mode of optimum performance is occupied usually by Coca of 15 minutes and best of all passes in process of a trial trip during which it is necessary to banish the car through all high-speed ranges and various loads of the engine, trying to support the frequency of rotation of the last in the range of 2500 ÷ of 3500 rpm.

The function chart of system of the distributed injection of Bosch Motronic of MP5.1

1 — ECU
2 — the VMT Sensor (turns of a bent shaft)
3 — the Sensor of pressure of the soaked-up air
4 — the Potentiometer of an axis of a butterfly valve
5 — the Sensor of temperature of cooling liquid
6 — the Sensor of temperature of the soaked-up air (IAT)
7 — the Sensor of the speed (VSS)
8 — the Oxygen sensor (l-probe)
9 — the Battery
10 — the Dual relay
11 — the ignition Coil
12 — the Fuel tank

13 — the Fuel pump
14 — the Fuel filter
15 — the Fuel highway and the inlet pipeline
16 — pressure Regulator
17 — injection Injectors
18 — the Coal adsorber
19 — the Valve of a purge of a coal adsorber
20 — the throttle Case
21 — the Sensor of heating of a throttle
22 — the Valve of additional air
23 — the Control lamp of system of self-diagnostics
24 — the Diagnostic socket

The scheme of air supply in the engine


1 — the Air cleaner/cover of a head of cylinders 2 — Location of an injector of injection	3 — the Inlet air path 4 — the Inlet pipeline 5 — the throttle Case

The function chart of system of the distributed Magneti-Marelli 8P injection

1 — ECU
2 — the Fuel tank
3 — the Submersible fuel pump
4 — the Dual relay of system of injection (ECU/pump)
5 — the Fuel filter
6 — injection Injectors
7 — pressure Regulator
8 — the Fuel highway
9 — the throttle Case
10 — the Potentiometer of an axis of a butterfly valve
11 — the Step motor of adjustment of turns of idling
12 — the Oxygen sensor (l-probe)
13 — the MAR Sensor

14 — the Sensor of temperature of cooling liquid
15 — the Sensor of provision of a bent shaft
16 — the ignition Coil
17 — the Battery
18 — the ignition Switch
19 — the Control lamp of system of self-diagnostics
20 — the Diagnostic socket
21 — the IAT Sensor
22 — the detonation Sensor
23 — the Heating element of the throttle camera
24 — the Electromagnetic valve of a purge of a coal adsorber
25 — the Coal adsorber
26 — VSS
27 — Spark plugs

The function chart of system of the distributed injection of Bosch Motronic of MP3.2

1 — ECU
2 — the engine RPM meter (on a flywheel)
3 — the Potentiometer of an axis of a butterfly valve
4 — the Sensor of temperature of cooling liquid
5 — the IAT Sensor
6 — the Sensor of position of pistons in cylinders (CYP)
7 — the Oxygen sensor (l-probe)
8 — the detonation Sensor
9 — VSS
10 — the Dual relay
11 — the ignition Module
12 — ignition Coils
13 — the Fuel tank
14 — the Fuel pump
15 — the Fuel filter

16 — pressure Regulator
17 — injection Injectors
18 — the Valve of a purge of a coal adsorber
19 — the Coal adsorber
20 — the Valve of additional air
21 — the throttle Case
22 — the Heating element of the throttle camera
23 — the Electromagnetic valve of switching of system of air supply
24 — the Vacuum pump
25 — Pneumatic capsules of system of air supply
26 — the Inlet pipeline
27 — the Control lamp of system of self-diagnostics
28 — the Diagnostic socket
29 — the Battery

The MP5.1 Bosch Motronic system (models of 1.8 l with RKPP)

The control system of the MP5.1 Bosch Motronic engine (see an illustration the Function chart of system of the distributed injection of Bosch Motronic of MP5.1) is used at a complete set of models of 1.8 l with RKPP. The system which part the catalytic converter of the closed contour and system of catching of fuel evaporations is meets the latest standards of environment protection. Detailed information on functioning of the part of system which is responsible for installations of ignition is provided in the Head Elektrooborudovaniye of the engine. The principle of supply of fuel in the engine is described below.

The fuel pump shipped in a gasoline tank carries out supply of fuel to the fuel highway of system of injection. The path of supply of fuel switched on the linear fuel filter preventing a contamination of injectors. The pressure of supply of fuel is controlled by pressure regulator installed to the fuel highway. If pressure in a power supply system rises above a preset value, the regulator provides excess fuel return back to a gasoline tank. All four injectors open at the same time at each turn of a bent shaft and provide injection of fuel in the inlet pipeline.

The electric control system consists of ECU and a set of information sensors:
   a) The potentiometer of a butterfly valve - informs ECU on position of the gate and extent of opening of a throttle;
   b) The sensor of temperature of cooling liquid - informs ECU on engine temperature;
   c) The sensor of temperature of the soaked-up air (IAT) - informs ECU about air temperature passing through the throttle case;
   d) the l-probe - informs ECU on the level of content of oxygen (O2) in the fulfilled gases (for more details see Systems of decrease in toxicity and production of the fulfilled gases);
   e) The sensor of provision of a bent shaft - informs ECU on the provision of a bent shaft and frequency of its rotation;
   f) The sensor of absolute pressure in the inlet pipeline (MAR) - informs to the ECU size of load of the engine (on depression depth in the inlet pipeline);
   g) The sensor of the speed (VSS) - informs ECU on the speed of the movement of the car.

ECU, on the basis of the analysis of the signals arriving from information sensors defines optimum composition of air-fuel mix of time at the moment and corrects it by adjustment of duration of opening of injectors of injection. Thus, the composition of mix is constantly controlled by ECU and all the time answers the current operating conditions of the engine (warming up, single turns, the movement with cruiser the speed, acceleration, braking by the engine, etc., etc.).

ECU exercises also complete control over idling turns via the valve of additional air in case of need providing a possibility of a perepuskaniye of the soaked-up air bypassing a throttle. At the closed butterfly valve of ECU operates opening of the valve, regulating thereby air supply in the inlet pipeline and supporting engine turns at the required level.

Besides the listed functions, ECU exercises control of functioning of systems of release and catching of fuel evaporations (see Systems of decrease in toxicity and production of the fulfilled gases).

The case of a throttle is equipped with an electric heating element, giving of power supply on which is also controlled by ECU, carrying out heating of the throttle camera at cold starts and preventing frosting of a butterfly valve.

Air moves in cylinders via four inlet channels with various cross section which is (consistently increasing). Air supply is regulated by a butterfly valve. The air filter is built in a head of cylinders and its cover at the same time serves as a head cover (see the illustration Scheme of Air Supply in the engine). Besides an air filtration the air cleaner serves also as an oil separator for removal of crankcase gases.

In case of violation of serviceability of functioning of any of information sensors, ECU automatically passes into the mode of the closed contour. At the same time the false data arriving from the faulty sensor are ignored and instead of them some average value of under control parameter put in memory of the control unit is used. Efficiency of functioning at the same time, remaining quite adequate, can decrease a little. Transition of system to the mode of the closed contour is followed by inclusion of the control lamp which is built in in an instrument guard. In the block of memory of ECU the corresponding code of malfunction registers.

At operation of a control lamp the car at the first opportunity should be driven away on car repair shop where full diagnostics of a control system of the engine with use of the special electronic reader will be made. The diagnostic socket for connection of the reader is located near the assembly block of safety locks on the car dashboard.

The Magneti-Marelli 8P system (models of 1.6 l, 1.8 l [with AT] and 2.0 l [except RFY])

The control system of the Magneti-Marelli 8P engine (see an illustration the Function chart of system of the distributed Magneti-Marelli 8P injection ) is used on models of 1.6 l, 1.8 l from AT and 2.0 l with 8-valvate engines. Information on functioning of the part of system which is responsible for installations of ignition is provided in the Head Elektrooborudovaniye of the engine.

The system by the principle of functioning is very close to Bosch MP5.1 described above. The only difference is made by a control system of idling turns.

In the Magneti-Marelli ECU system exercises control of idling turns by means of the special step motor installed on the throttle case. The motor is equipped with the pusher controlling extent of opening of the bypass canal on which air is bypassed in the inlet pipeline bypassing the throttle camera. At the closed butterfly valve of ECU exercises control of air supply in the inlet pipeline by means of the step motor, providing control over idling turns. The bypass is used also as a source of additional air at cold starts of the engine.

MP3.2 Bosch Motronic system (model of 2.0 l of RFY)

This system (see an illustration the Function chart of system of the distributed injection of Bosch Motronic of MP3.2 ) is used on models of 2.0 l with 16-valvate engines (RFY) and in the present manual is not subject to detailed consideration. Let's notice only that many components perform the same functions that the same components of the Magneti-Marelli system, taking into account the listed below differences.

Injection injectors in the distributive pipeline have individual management. Fuel is injected into cylinders in turn through each two turns of a bent shaft.

The regulator of pressure of fuel provides a constant pressure in 3 bars at any modes of operation of the engine.

The system of an admission of air of 16-valvate RFY engines has a special design. Let's not go deep in particular functioning of the inlet pipeline, we will specify only that the pipeline consists of two channels of various length and various cross section. This system allows to achieve increase in torque of the engine on low turns.

ECU provides interruption in supply of fuel at the movement with a setup on turns lower than 1280 a minute and renews food at excess of this value.

For protection of the engine against overloads the injection of fuel is interrupted at excess by the frequency of rotation of the engine of value in 6840 rpm. The RPM meter is installed on a head of cylinders.

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