6.8. System of injection of fuel - the general information

System of injection of LH-Jetronic fuel

Scheme of system of injection of LH-Jetronic fuel



1 — the Fuel tank
2 — the Fuel pump
3 — the Preliminary fuel pump
4 — the Fuel filter
5 — Fuel distributive
highway
6 — the fuel pressure Regulator
7 — the Electronic device
managements (ECU)
8 — the Distributor
9 — the ignition Coil
10 — temperature Sensor
11 — the injection Gate (injector)

12 — Vacuum lines
13 — the Inlet pipeline
14 — the Sensor of provision of a throttle
15 — the Valve of additional air
(idling stabilization)
16 — the Measuring instrument of an air stream
17 — the Lambda probe (models with the catalytic converter)
18 — pressure Switch (models with a turbo-supercharging)
19 — the system Relay
20 — the Relay of the fuel pump
21 — the Battery
22 — the Ignition key


System of injection of LH-Jetronic fuel - the microprocessor control system of fuel supply which is constantly processing information on a condition of the engine from various sensors and providing giving of the required amount of fuel for its full combustion at any condition of the engine.

Data from sensors are processed in the electronic control unit (ECU) of fuel system and on the basis of the received result the period of opening of injectors for injection in the inlet pipeline of the required amount of fuel is defined. This system is system of simultaneous type that means that opening and closing of all injectors happens in one and too time. Injectors open once on each turn of the crankshaft, excepting the mode of cold start when they open twice for one turn.

On the models equipped with system of a turbo-supercharging, made till 1989 for management of functioning of a turbocompressor the separate electronic actuation device (ECU) is used; since 1989 and later for these purposes the electronic actuation device of system of direct ignition is used. On the models equipped with the catalytic converter (late models) LH-Jetronic also the lambda probe logs in. The main components of system is the following:

   a) Electronic actuation device (ECU):

The electronic actuation device completely operates work of system of injection of fuel.

   b) Injectors:

Each injector of fuel consists of the needle valve operated by an electromagnet which opens on command from the electronic actuation device. Fuel from the fuel highway through a nozzle of an injector comes to the inlet pipeline.

    c) Measuring instrument of an air stream:

The measuring instrument of an air stream determines quantity by extent of cooling of the heated control wire, the air coming to the engine.

   d) Temperature sensor:

The sensor of temperature of a cooler determines engine temperature.

   e) Valve of additional air:

The valve provides giving in the cold engine of additional air. The valve is installed only on models of 1985 of the issue.

   f) Idling stabilization valve:

The valve controls the volume of the air making a detour of the gate of a throttle. The valve is installed only on models since 1986 by the issue.

   g) Sensor of provision of a throttle:

The sensor switch of provision of a throttle informs the electronic actuation device on the provision of a butterfly valve.

   h) Fuel pump:

The fuel pump is placed in the fuel tank. In a casing of the pump there is a separate preliminary pump providing giving to the main fuel pump of the fuel purified of air bubbles and which is under pressure.

   i) Fuel filter:

The fuel filter is installed behind the battery in a motive compartment.

   j) Lambda probe:

The lambda probe provides the electronic actuation device with information on the content of oxygen in exhaust gases. The lambda probe is established on late models with the catalytic converter.

   k) Injector of cold start:

The injector of cold start is established on some models and provides additional supply of fuel in the inlet pipeline during the limited period at start of the engine.

Control system of the Trionic engine

The control system of the Trionic engine of SAAB by means of the uniform block of the electronic actuation device (ECU) controls execution of three functions of the engine. The system of injection of fuel, system of ignition, and (where is available) system of a turbo-supercharging are subject to control.
The system is run by the microprocessor and provides giving with fuel system, the amount of fuel demanded for full combustion at any power setting. The electronic actuation device processes the data arriving from various sensors and defines the period of opening of injectors for injection of the required amount of fuel in the inlet pipeline. The system is system of consecutive type that means that fuel is injected according to an engine ignition order. At the first inclusion of ignition and after turning on of the fuel pump all injectors for the purpose of giving of a small amount of fuel in the neighborhood of inlet valves for a short time join. It provides more bystry start of the engine.

The main components of system is the following:

   a) Electronic actuation device (ECU):

The device completely controls work of system of injection of fuel, system of ignition and system of a turbo-supercharging.

   b) Sensor of position of the crankshaft:

The sensor of position of the crankshaft provides the electronic actuation device with the data necessary for calculation of position of the crankshaft in relation to the top dead point.

   c) Sensor of absolute pressure of the pipeline (MAP):

The MAP sensor gives to the electronic actuation device tension proportional to pressure in the inlet pipeline.

   d) The sensor of temperature of the soaked-up air:

The sensor of temperature of the soaked-up air provides the electronic actuation device with the signals allowing to determine density of the air coming to the engine.

   e) Engine cooler temperature sensor:

The sensor of temperature of a cooler of the engine informs the electronic actuation device on engine temperature.

   f) Sensor switch of provision of a throttle:

Informs the electronic actuation device on the provision of a butterfly valve.

   j) Lambda probe:

Provides the electronic actuation device with information on the content of oxygen in exhaust gases. The lambda probe of production of Bosch is usually applied.

   h) Block of direct ignition:

Consists of 4 high-voltage coils connected directly to spark plugs.

   i) Injectors:

Each injector consists of the needle valve operated by an electromagnet which opens on command from the electronic actuation device. Fuel from the fuel highway through a nozzle of an injector is injected into the inlet pipeline. Injectors of production of BOSCH are usually applied.

   g) Electromagnetic valve of management of pressure of the supercharger:

Controls functioning of a turbocompressor. Under certain conditions (for example, at inclusion of the 1st transfer) pressure goes down.

   k) Idling stabilization valve:

Operates the volume of the air making a detour of a butterfly valve. The system supports turns of idling of the engine regardless of the loading caused by operation of the generator, compressor of the air conditioning system or inclusion of the transfers other than P or N on models with automatic transmission. At emergence of break in an electric contour of the valve of stabilization of idling opening of the valve is defined by an internal spring and establishes engine turns approximately on 1000 rpm.

   l) EVAP adsorber purge valve:

It is involved at start of the engine for a conclusion of the fuel which accumulated in an adsorber to allow to compensate a lambda probe mix enrichment, the system works with short intervals.

   m) Fuel pump:

The fuel pump settles down in a gasoline tank. In a casing of the fuel pump there is a separate preliminary pump giving to the main fuel pump under pressure the compressed fuel cleared of air bubbles.

   n) Fuel filter:

It is located behind under the car bottom near the fuel tank and serves for purification of the fuel arriving from the fuel pump.

At fire of an alarm lamp of system the car has to at the first opportunity be driven away for survey in representative office of SAAB. Here the full test of a control system of the engine with use of the special electronic diagnostic equipment which is simply connected to diagnostic plugs of system can be carried out.