Citroen Xantia

since 1993 of release

Repair and car operation

Systems of injection of fuel - the general information

In systems of injection of fuel the electronic control unit (ECU) of being self-adjusted type is used. In the course of functioning of ECU traces and keeps in memory of the 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 base parameters entered into the block of memory at manufacturer. In view of told at primary start after battery connection the engine can unstably work for some time. Process of an exit of ECU in a mode of optimum performance is occupied usually by Coca of 15 minutes and best of all takes place 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 frequency of rotation of the last in a range of 2500 ÷ 3500 rpm.

Function chart of system of the distributed injection of Bosch Motronic MP5.1

1 — ECU
2 — the VMT Sensor (turns of a cranked shaft)
3 — the Sensor of pressure of 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 soaked-up air (IAT)
7 — the Sensor of 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 — a 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 supply of air in the engine


1 — the Air purifier/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

Function chart of system of the distributed injection of Magneti-Marelli 8Р

1 — ECU
2 — the Fuel tank
3 — Pogruzhna the fuel pump
4 — the Dual relay of system of injection (ECU/pump)
5 — the Fuel filter
6 — injection Injectors
7 — a pressure Regulator
8 — the Fuel highway
9 — the throttle Case
10 — the Potentiometer of an axis of a butterfly valve
11 — the Step-by-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 cranked 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 chamber
24 — the Electromagnetic valve of a purge of a coal adsorber
25 — the Coal adsorber
26 — VSS
27 — Spark plugs

Function chart of system of the distributed injection of Bosch Motronic MP3.2

1 — ECU
2 — the Sensor of turns of the engine (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 — a 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 chamber
23 — the Electromagnetic valve of switching of system of supply of air
24 — the Vacuum pump
25 — Pneumatic capsules of system of supply of air
26 — the Inlet pipeline
27 — the Control lamp of system of self-diagnostics
28 — the Diagnostic socket
29 — the Battery

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

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

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

The electric control system consists of ECU and a set of information sensors:
   a) The butterfly valve potentiometer - informs ECU on the provision of a zaslonka 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 soaked-up air (IAT) - informs ECU on the air temperature, a throttle passing through the case;
   d) the l-probe - informs ECU on level of the content of oxygen (О2) 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 cranked shaft - informs ECU on the provision of a cranked shaft and frequency of its rotation;
   f) The sensor of absolute pressure in the inlet pipeline (MAR) - informs to ECU size of load of the engine (on depth of depression in the inlet pipeline);
   g) The sensor of speed (VSS) - informs ECU on speed of movement of the car.

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

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

Besides the listed functions, ECU exercises administration 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 power supply giving on which also supervises ECU, carrying out heating of the throttle chamber at cold starts and preventing a butterfly valve icing.

Air moves in cylinders via four inlet channels with various cross-section section (consistently increasing). Supply of air 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 an illustration the Scheme of supply of air in the engine). Besides an air filtration the air purifier serves also as an oil separator for removal of karterny gases.

In case of violation of serviceability of functioning of any of information sensors, ECU automatically passes to a mode of the closed contour. False data thus arriving from the faulty sensor are ignored and instead of them some is used put in memory of the control unit average value of under control parameter. Efficiency of functioning thus, remaining quite adequate, can decrease a little. Transition of system to a mode of the closed contour is accompanied by inclusion of the control lamp 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 possibility should be driven away on car repair shop where complete diagnostics of a control system by the engine with use of the special electronic input reader will be made. The diagnostic socket for connection of the input reader is located near the assembly block of safety locks on the car dashboard.

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

The control system of the Magneti-Marelli 8Р engine (see an illustration the Function chart of system of the distributed injection of Magneti-Marelli 8Р ) is used on models of 1.6 l, 1.8 l from AT and 2.0 l with 8-клапанными engines. Information on functioning of responsible installation of ignition of a part of system is provided in Head engine Electric equipment.

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

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

Bosch Motronic MP3.2 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 MP3.2 ) is used on models of 2.0 l with 16-klapanny engines (RFY) and in the real Management to detailed consideration is not subject. Let's notice only that many components carry out the same functions that the same components of Magneti-Marelli system, taking into account 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 cranked shaft.

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

The system of an admission of air of 16-klapanny 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 section. This system allows to achieve increase in a torque of the engine on low turns.

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

For protection of the engine against overloads injection of fuel interrupts at excess by frequency of rotation of the engine of value in 6840 rpm. The sensor of turns is established on a head of cylinders.