MOBILKU

There are plenty of super yacht concepts that I'll never touch, much less own—such as ones with three level designs or impossible masts—but I'm still happy that a design finally includes a built-in garage. And a super car.

The Strand Craft 122 design is a crazy 38 meter beauty that comes with room for an even crazier concept car:

The most stunning feature on this yacht is a special handcrafted supercar (Tender) powered by a 880hp twin turbo V12 engine with topspeed 375kmh can be housed in as a tender in the stern garage.

Ah, maybe one day concepts like this will be real—and affordable enough that all of us can take a lazy trip around the world. [Gray Design via Luxist]

Electronic fuel injection 1

In this tutorial we will be looking at the Electronic Fuel Injection system, with particular focus upon the sensors and actuators, and their inputs and outputs to and from the vehicle's ECM. The tutorial looks at the multi-point injection system, with single-point being covered in a later tutorial.

Overview

Both the multi-point and the single-point systems operate in a very similar fashion, having an electromechanically operated injector or injectors opening for a predetermined length of time called the injector pulse width. The pulse width is determined by the engine’s Electronic Control Module (ECM and depends on the engine temperature, the engine load and the information from the oxygen (lambda) sensor. The fuel is delivered from the tank through a filter, and a regulator determines its operating pressure. The fuel is delivered to the engine in precise quantities and in most cases is injected into the inlet manifold to await the valve’s opening, then drawn into the combustion chamber by the incoming air.

The Fuel Tank

This is the obvious place to start in any full system explanation. Unlike the tanks on early carburettor-equipped vehicles, it is a sealed unit that allows the natural gassing of the fuel to aid delivery to the pump by slightly pressurising the system. When the filler cap is removed, pressure is heard to escape because the fuel filler caps are no longer vented.

The Fuel Pump

This type of high-pressure fuel pump (Fig 1.0) is called a roller cell pump, with the fuel entering the pump and being compressed by rotating cells which force it through the pump at a high pressure. The pump can produce a pressure of 8 bar (120 psi) with a delivery rate of approximately 4 to 5 litres per minute. Within the pump is a pressure relief valve that lifts off its seat at 8 bar to arrest the pressure if a blockage in the filter or fuel lines or elsewhere causes it to become obstructed. The other end of the pump (output) is home to a non-return valve which, when the voltage to the pump is removed, closes the return to the tank and maintains pressure within the system. The normal operating pressure within this system is approximately 2 bar (30 psi), at which the current draw on the pump is 3 to 5 amps. Fuel passing across the fuel pump's armature is subjected to sparks and arcing; this sounds quite dangerous, but the absence of oxygen means that there will not be an explosion!

Figure 1.0

The majority of fuel pumps fitted to today’s motor vehicles are fitted within the vehicle’s petrol tank and are referred to as ‘submerged’ fuel pumps. The pump is invariably be located with the fuel sender unit and both units can sometimes be accessed through an inspection hole either in the boot floor or under the rear seat. Mounted vertically, the pump comprises an inner and outer gear assembly that is called the ‘gerotor’. The combined assembly is secured in the tank using screws and sealed with a rubber gasket, or a bayonet-type locking ring. On some models, there are two fuel pumps, the submerged pump acting as a ‘lift’ pump to the external roller cell pump.

Figure 1.1

Figure 1.2

The waveform illustrated in Fig 1.1 shows the current for each sector of the commutator. The majority of fuel pumps have 6 to 8 sectors, and a repetitive point on the waveform can indicate wear and an impending failure. In the illustration waveform it can be seen that there is a lower current draw on one sector and this is repeated when the pump has rotated through 720°. This example has 8 sectors per rotation.

Fig 1.2 shows typical access to the fuel-submerged pump to measure current draw.
The current drawn by the fuel pump depends upon the fuel pressure but should be no more than 8 amps, as found on the Bosch K-Jetronic mechanical fuel injection which has a system pressure of 75 psi.

Fuel Supply

A conventional ‘flow and return’ system has a supply of fuel delivered to the fuel rail, and the unwanted fuel is passed through the pressure regulator back to the tank. It is the restriction in the fuel line created by the pressure regulator that provides the system operational pressure.

Returnless Fuel Systems

Have been adopted by several motor manufacturers and differ from the conventional by having a delivery pipe only to the fuel rail with no return flow back to the tank.
The returnless systems, both the mechanical and the electronic versions, were necessitated by emissions laws. The absence of heated petrol returning to the fuel tank reduces the amount of evaporative emissions, while the fuel lines are kept short, thus reducing build costs.

Mechanical Returnless Fuel Systems

The ‘returnless’ system differs from the norm by having the pressure regulator inside the fuel tank. When the fuel pump is activated, fuel flows into the system until the required pressure is obtained; at this point ‘excess’ fuel is bled past the pressure regulator and back into the tank.
The ‘flow and return’ system has a vacuum supply to the pressure regulator: this enables the fuel pressure to be increased whenever the manifold vacuum drops, providing fuel enrichment under acceleration.
The ‘returnless’ system has no mechanical compensation affecting the fuel pressure, which remains at a higher than usual 44 to 50 psi. By increasing the delivery pressure, the ECM (Electronic Control Module) can alter the injection pulse width to give the precise delivery, regardless of the engine load and without fuel pressure compensation.

Electronic Returnless Fuel Systems

This version has all the required components fitted within the one unit of the submersible fuel pump. It contains a small particle filter (in addition to the strainer), pump, electronic pressure regulator, fuel level sensor and a sound isolation system. The electronic pressure regulator allows the pressure to be increased under acceleration conditions, and the pump’s output can be adjusted to suit the engine's fuel demand. This prolongs the pump’s life as it is no longer providing a larger than required output delivery.
The Electronic Control Module (ECM) supplies the required pressure information, while the fuel pump’s output signal is supplied in the form of a digital squarewave. Altering the squarewave’s duty cycle affects the pump’s delivery output.
To compensate for the changing viscosity of the fuel with changing fuel temperature, a fuel rail temperature sensor is installed. A pulsation damper may also be fitted ahead of or inside the fuel rail.

Injectors

The injector is an electromechanical device, which is fed by a 12 volt supply from either the fuel injection relay or the ECM. The voltage is present only when the engine is cranking or running, because it is controlled by a tachometric relay. The injector is supplied with fuel from a common fuel rail. The injector pulse width depends on the input signals seen by the ECM from its various engine sensors, and varies to compensate for cold engine starting and warm-up periods, the initial wide pulse getting narrower as the engine warms to operating temperature. The pulse width also expands under acceleration and contracts under light load conditions.
The injector has constant voltage supply while the engine is running and the earth path is switched via the ECM. An example of a typical waveform is shown below in Fig 1.3.

Figure 1.3

Multi-point injection may be either sequential or simultaneous. A simultaneous system fires all 4 injectors at the same time with each cylinder receiving 2 injection pulses per cycle (720° crankshaft rotation). A sequential system receives just 1 injection pulse per cycle, timed to coincide with the opening of the inlet valve. As a very rough guide the injector pulse widths for an engine at normal operating temperature at idle speed are around 2.5 ms for simultaneous and 3.5 ms for sequential.
An electromechanical injector of course takes a short time to react, as it requires a level of magnetism to build before the pintle is lifted off its seat. This time is called the ‘solenoid reaction time’. This delay is important to monitor and can sometimes occupy a third of the total pulse width. A good example of the delay in opening can be seen in the example waveform shown below in Fig 1.4.
The waveform is ‘split’ into two clearly defined areas. The first part of the waveform is responsible for the electromagnetic force lifting the pintle, in this example taking approximately 0.6 ms. At this point the current can be seen to level off before rising again as the pintle is held open. With this level off ind it can be seen that the amount of time that the injector is held open is not necessarily the same as the time measured. It is not however possible to calculate the time taken for the injector’s spring to fully close the injector and cut off the fuel flow.
This test is ideal for identifying an injector with an unacceptably slow solenoid reaction time. Such an injector would not deliver the required amount of fuel and the cylinder in question would run lean.

Figure 1.4

Fig 1.5 shows both the injector voltage and current displayed simultaneously.

Figure 1.5

All the example waveforms used were recorded using a Pico automotive oscilloscope. Other manufacturers’ equipment will have different voltage ranges but the resultant picture should be very similar. Please remember that using a higher voltage range will result in the waveform being vertically compressed, although the indicated voltage will be the same.

In the next tutorial we will be looking at the input signals to the ECM that control the injection pulse width.

This tutorial was first published by The Institute of the Motor Industry

Teknologi Hibrida Sederhana dan Murah

Sistem hibrida Hyundai, kopling dipasangkan pada motor listrik dan roda gila.

KOMPAS.com-Dengan semakin ketatnya standar konsumsi bahan bakar, produsen berusaha melakukan terobosan, yaitu menciptakan mobil hibrida dengan sistem yang lebih sederhana. Tujuannya, untuk menekan biaya produksi.

Mulai tahun ini, Hyundai dan Volkswagen akan memperkenalkan konfigurasi hibrida paralel, mengandalkan tenaga listrik murni, tenaga listrik tambahan, rem regeneratif dan sistem stop/start. Cara yang dilakukan, menghubungkan penggerak hibrida ke transmisi otomatik. Untuk ini, sistem tidak lagi menggunakan dua motor listrik, hanya satu.

Teknologi ini akan digunakan Hyundai pada Sonata hibrida dengan gerak roda depan dan diikuti oleh Kia Optima. Sedangkan VW mengaplikasikannya pada Touareg dan Porsche Cayenne hibrida.

Kedua perusahaan menggunakan komputer untuk mengontrol kerja kopling yang berada antara mesin dan motor listrik. Kopling yang digunakan Hyundai, tipe pelat banyak (multi-plate) yang diredam dalam oli (wet). Motor listriknya, mampu menghasilkan tenaga 30 kW, sedangkan Volkswagen 38 kW.

Cara Kerja
Cara kerja, ketika kopling dilepas, motor listrik berputar melalui transmisi otomatik untuk menjalankan mobil (hanya mengandalkan tenaga listrik). Kedua sistem mulai bekerja saat mobil pertama kali dijalankan.
Ketika kopling dioperasikan dan mesin hidup, tenaga diteruskan ke transmisi melalui motor listrik. Motor listrik hanya berputar sebagai komponen roda gila (pada sistem Hyundai). Pada VW, bila diperlukan, motor berfungsi sebagai generator.
Jika ada kebutuhan, arus listrik dari baterai dipasok ke motor listrik untuk berakselerasi atau menambah tenaga mesin. Saat mobil direm, motor bekerja sebagai generator (regenerative braking).
Hyundai menambahkan motor/generator tegangan tinggi yang digerakkan oleh belt, 8kW pada mesin 2,4 liter. Moto dan generator ditempatkan pada generator konvensional. Tugasnya, menghidupkan mesin dan mengisi baterai bertegangan 270 volt yang memungkinkan mesin tetap hidup kendati mobil bekerja dengan mode listrik murni.
Dibandingkan dengan generator motor yang lebih besar dan disatukan pada sistem lain, desain ini biayanya lebih murah. Kendati demikian, agar seluruh sistem hibrida berfungsi dengan satu motor diperlukan lagi kopling tambahan, misalnya torque coverter seperti yang digunakan oleh VW. Hyyundai tidak menggunakan untuk membuat sistem ringkas dan lebih efisien.

ENGINE MANAGEMENT SYSTEM - MPi

The Engine Control Module (ECM) monitors the conditions required for optimum combustion of fuel in the cylinder through sensors located at strategic points around the engine. From these sensor inputs, the engine control module can adjust the fuel quantity and timing of the fuel being delivered to the cylinders.
The main features are as follows:
- A single ECM controls the fuel injection system and the ignition system. The ECM incorporates short circuit protection and can store intermittent faults on certain inputs. TestBook can interrogate the ECM for these stored faults.
- The ECM is electronically immobilised preventing the engine from being started unless it receives a coded signal from the anti-theft control unit.
- In conjunction with the throttle position sensor the ECM uses the speed/density method of air flow measurement to calculate fuel delivery. This method measures the inlet air temperature and inlet manifold pressure and assumes that the engine is a calibrated vacuum pump, with its characteristics stored in the ECM, it can then determine the correct amount of fuel to be injected.
- A separate diagnostic connector, located on the passenger compartment fusebox, allows engine tuning or fault diagnosis to be carried out using TestBook without disconnecting the ECM harness multiplug.
- The ECM harness multiplug incorporates specially plated pins to minimise oxidation and give improved reliability.
- The ECM controls the operation of the radiator and air conditioning cooling fans, based on signals received from the engine coolant temperature sensor and trinary switch. The engine compartment cooling fan receives signals from the ambient air temperature sensor. If a high engine coolant temperature is detected the ECM will prevent the air conditioning system from operating.
- If certain system inputs fail, the ECM implements a back-up facility to enable the system to continue functioning, although at a reduced level of performance.

IGNITION SYSTEM - MPi MEMS 1.9
The ECM determines the optimum ignition timing based on the signals from the following sensors:
1. Crankshaft position sensor - Engine speed and crankshaft position
2. Manifold absolute pressure sensor - Engine load
3. Engine coolant temperature sensor - Engine temperature
4. Manifold absolute pressure sensor - Throttle pedal released
The engine management system uses no centrifugal or vacuum advance. Timing is controlled by the ECM which is energised by the main relay within the relay module. Spark distribution is achieved by means of a rotor arm and distributor mounted at the No.4 cylinder end of the inlet camshaft.

BASIC IGNITION TIMING - MPi
Crankshaft position sensor
The speed and position of the engine is detected by the crankshaft position (CKP) sensor which is bolted to, and projects through, the engine adapter plate adjacent to the flywheel. The CKP sensor is an inductive sensor consisting of a bracket mounted body containing a coil and a permanent magnet which provides a magnetic field. The CKP sensor is situated so that an air gap exists between it and the flywheel. Air gap distance is critical for correct operation. The flywheel incorporates a reluctor ring which consists of 32 poles spaced at 1°intervals, with 4 missing poles at °, 12°, 18° and 31°. The missing poles inform the ECM when to operate the groups of injectors. When the flywheel rotates, as a pole passes the CKP sensor it disturbs the magnetic field inducing a voltage pulse in the coil. This pulse is transmitted to the ECM. By calculating the number of pulses that occur within a given time, the ECM can determine the engine speed. The output from the CKP sensor when used in conjunction with that from the manifold absolute pressure sensor provides idle stabilisation and reference for injection timing.
Manifold absolute pressure sensor
The manifold absolute pressure (MAP) sensor is located within the ECM and detects manifold pressure via a hose connected to the inlet manifold. The MAP sensor converts pressure variations into graduated electrical signals which can be read by the ECM. Increases and decreases in the manifold pressure provide the ECM with an accurate representation of the load being placed on the engine allowing the ECM to adjust the quantity of fuel being injected and the ignition timing to achieve optimum fuelling of the engine.
IGNITION TIMING COMPENSATION - MPi
Engine coolant temperature sensor
The engine coolant temperature (ECT) sensor is a thermistor (a temperature dependent resistor), i.e. the voltage output varies in proportion to temperature. The ECT sensor is located in the front of the coolant outlet elbow and can be distinguished from the gauge sensor by its brown colour. The ECM constantly monitors this signal and uses the information to provide optimum driveability and emissions by advancing or retarding the ignition timing.
Idle speed control
With the throttle pedal released and the engine at idle, the ECM uses the fast response of ignition timing to maintain idle stabilisation. When loads are placed on or removed from the engine, the ECM senses the change in engine speed, and in conjunction with adjusting the idle air control (IAC) valve, advances or retards the ignition timing to maintain a specified idle speed. When load is removed from the engine, the IAC valve returns to its original position and the ignition timing returns to the idle setting.
NOTE: Due to the sensitivity of this system the ignition timing will be constantly changing at idle speed.

IGNITION COMPONENTS -MPi
Ignition coil
The coil for the programmed ignition system is mounted on the back of the engine. The coil has a lower primary winding resistance (0.63 to 0.77 ohms at 2°C) than a coil in a conventional ignition system. This allows the full h.t. output to be reached faster and so makes the coil operation more consistent throughout the engine speed range.
Distributor cap and rotor arm
1. Distributor cap
2. Rotor arm
3. Retaining screw
4. Anti-flash shield
The distributor cap, carrying a central carbon brush and four h.t. lead pick-ups, is located at the No.4 cylinder end of the inlet camshaft and surrounds the rotor arm. The rotor arm is secured by a retaining screw to a 'D' shaped stub shaft, which is press fitted into a vibration absorbing bush in the camshaft, and is protected from oil contamination by an anti-flash shield which incorporates an oil drain.
FUEL SYSTEM - MPi
Engine Control Module (ECM)
The Modular Engine Management System (MEMS) is controlled by an ECM mounted on the bulkhead in the engine compartment. The ECM is an adaptive unit which over a period of time learns the load and wear characteristics of the engine it controls. The ECM remembers and updates two main engine requirements when the engine is running at normal operating temperature:
1. The position of the idle air control (IAC) valve required to achieve a specified idle speed. This is then used as a reference for IAC valve movement to achieve idle speed under all load conditions.
2. The fuelling change or offset required to achieve a set oxygen sensor output indicating an air fuel ratio of 14.7:1. This allows the system to provide the correct fuelling without having to apply excessive adjustments to the fuelling which can adversely affect the emissions and driveability.
NOTE: After fitting a different ECM, TestBook will be required to reprogram the ECM with the code from the anti-theft control unit and to perform a full engine tune procedure.
The ECM inputs and outputs are shown in the following table.
INPUTS
Crankshaft position sensor
Ambient air temperature sensor
Manifold absolute pressure sensor
Engine coolant temperature sensor
Intake air temperature sensor
Heated oxygen sensor
Throttle position sensor
Diagnostic input
Battery supply
Starter signal
Earth supply
Anti-theft control unit
A/C Trinary switch
OUTPUTS
Ignition coil
Injectors
Idle air control valve
ECM Fuel pump relay
Diagnostic connector
Heated oxygen sensor relay
Main relay
Cooling fans
Air conditioning fans
Engine bay fans
Purge valve
Intake air temperature sensor
The intake air temperature (IAT) sensor is located in the side of the inlet manifold. The IAT sensor is of the negative temperature coefficient (NTC) type, designed to reduce its resistance with increasing temperature. The ECM receives a signal from the IAT sensor proportional to the temperature of the intake air. When this signal is used in conjunction with the signal from the manifold absolute pressure sensor. The ECM calculates the volume of oxygen in the air and adjusts the quantity of fuel being injected, to achieve optimum fuelling of the engine.

Injectors
The four fuel injectors are fitted between the pressurised fuel rail and inlet manifold. Each injector comprises a solenoid operated needle valve and a specially designed nozzle to ensure good fuel atomisation. The injectors are controlled in grouped mode with 2 & 3 being grouped and 1 & 4 being grouped, with the injectors in each group being operated alternatively. The ECM determines when to operate the injectors based on the signal it receives from the crankshaft position sensor. The ECM provides an earth signal for the period the injectors are required to be open, the injector solenoids are energised and fuel is sprayed into the inlet manifold onto the back of the inlet valves. The ECM carefully meters the amount of fuel injected by adjusting the injector opening period (pulse width). During cranking, when the engine speed is below approximately 400 rev/min, the ECM increases the injector pulse width to aid starting. The amount of increase depends upon engine coolant temperature. To prevent flooding, the ECM periodically inhibits the operation of the injectors.
Throttle housing
The throttle housing is located between the inlet manifold and air intake hose and is sealed to the manifold by an O-ring. The throttle housing incorporates a throttle disc which is connected to the throttle pedal via the throttle lever and a cable. There are two breather pipes connected to the throttle housing, one either side of the throttle disc. When the engine is running with the throttle disc open, both pipes are subject to manifold depression and draw crankcase fumes into the manifold. When the throttle disc is closed, only the pipe on the inlet manifold side of the disc is subject to manifold depression. This pipe incorporates a restrictor to prevent engine oil being drawn into the engine by the substantially greater manifold depression. Mounted on the throttle housing are the throttle position sensor and idle air control valve.

Throttle position sensor
The throttle position (TP) sensor is a potentiometer attached to the throttle housing and is directly coupled to the throttle disc. The TP sensor is non-adjustable. Closed throttle is detected by the TP sensor which initiates idle speed control via the idle air control valve. The ECM supplies the TP sensor with a 5 volt supply and an earth path. The TP sensor returns a signal proportional to throttle disc position. Throttle disc movement causes voltage across the TP sensor to vary. The ECM calculates the rate of change of the voltage signal in positive (acceleration) or negative (deceleration) directions. From this the ECM can determine the required engine speed, rate of acceleration or rate of deceleration and apply acceleration enrichment, deceleration fuel metering or over-run fuel cut-off.

Idle air control valve
The idle air control (IAC) valve is mounted on the inlet manifold and controlled by the ECM. The IAC valve opens a pintle valve situated in an air passage in the throttle housing, allowing air to bypass the throttle disc and flow straight into the inlet manifold. By changing the amount the IAC valve is open the ECM can control engine idle speed and cold start air flow requirements by adjusting the flow of air in the passage. During cold starting the ECM indexes the IAC valve open slightly to provide a level of fast idle, dependent on engine coolant temperature. As the engine warms, fast idle is gradually decreased until normal operating temperature is reached. The position of the IAC valve can be checked using TestBook and should be within the range of 20 to 40 steps when the engine is running. If it is identified as being outside this range it can be adjusted to within range using TestBook. This ensures that the IAC valve is at the optimum position within its range for providing further movement to compensate for changes in engine load or temperature in accordance with signals from the ECM.
NOTE: The position of the throttle disc is preset during manufacture and the throttle position setting screw MUST NOT be adjusted.

Engine management relay module
The relay module is located on the bulkhead in the engine compartment behind the engine control module. The relay module contains the following relays:
- Main relay - energised when the ignition is switched on and supplies power to the ECM.
- Fuel pump relay - energised by the ECM for a short period when the ignition is switched on, during cranking and while the engine is running. - Starter relay - energised by the cranking signal from the ignition switch.
- Heated oxygen sensor relay - energised by the ECM and supplies current to the heated oxygen sensor element.

Fuel pump
The electric fuel pump is located inside the fuel tank and is energised by the ECM via the fuel pump relay in the relay module and the fuel cut-off inertia switch. The fuel pump delivers more fuel than the maximum load requirement for the engine, pressure is therefore maintained in the fuel system under all conditions.

Fuel pressure regulator
The pressure regulator is a mechanical device controlled by manifold depression and is mounted on one end of the fuel rail. The regulator ensures that fuel rail pressure is maintained at a constant pressure difference to that in the inlet manifold, as manifold depression increases the regulated fuel pressure is reduced in direct proportion. When pressure exceeds the regulator setting, excess fuel is returned to the fuel tank swirl pot which contains the fuel pump pick-up.

Inertia fuel shut-off switch
The electrical circuit for the fuel pump incorporates an inertia fuel shut-off (IFS) switch which, in the event of a sudden deceleration, breaks the circuit to the fuel pump preventing fuel being delivered to the engine. The IFS switch is situated in the engine compartment next to the ECM, and must be reset by pressing the rubber top before the engine can be restarted.
WARNING: ALWAYS check for fuel leaks and the integrity of fuel system
connections before resetting the switch.

Diagnostic connector
A diagnostic connector, located on the passenger compartment fusebox, allows engine tuning or fault diagnosis to be carried out using TestBook without disconnecting the ECM harness multiplug.

Heated oxygen sensor
The modular engine management system operates a closed loop emission system to ensure the most efficient level of exhaust gas conversion. Amend text and include subscript commands A heated oxygen sensor (HO2S) fitted in the exhaust manifold monitors the exhaust gases. It then supplies a small voltage proportional to exhaust oxygen content to the ECM. As the air/fuel mixture weakens, the exhaust oxygen content increases and so the voltage to the ECM decreases. If the mixture becomes richer so the oxygen content decreases and the voltage increases. From this signal the ECM can determine the air/fuel mixture being delivered to the engine, and can adjust the duration the injectors are open to maintain the ratio necessary for efficient gas conversion by the catalyst. The HO2S has an integral heating element to ensure an efficient operating temperature is quickly reached from cold. The electrical supply to the heater element is controlled by the ECM via the HO2S relay in the relay module.

Acceleration enrichment
When the throttle pedal is depressed, the ECM receives a rising voltage from the throttle position sensor and detects a rise in manifold pressure from the manifold absolute pressure sensor. The ECM provides additional fuel by increasing the normal injector pulse width and also provides a small number of extra additional pulses on rapid throttle openings.

Over-run fuel cut-off
The ECM implements over-run fuel cut-off when the engine speed is above 2000 rev/min with engine at normal operating temperature and the throttle position sensor in the closed position, i.e. the vehicle is "coasting" with the throttle pedal released. The ECM indexes the idle air control valve open slightly to increase the air flow through the engine to maintain a constant manifold depression to keep emissions low. Fuel is progressively reinstated as the throttle position sensor is opened.

Over-speed fuel cut-off
To prevent damage at high engine speeds the ECM will implement fuel cut-off at engine speeds above 7000 rev/min by inhibiting the earth path for the injectors, as engine speed falls to 6990 rev/min, fuel is progressively reinstated.

Ignition switch off
When the ignition is switched off, the ECM will keep the main relay energised for approximately 30 seconds while it drives the idle air control valve to its power down position, ready for the next engine start. The ECM then monitors the engine bay temperature using the ambient air temperature sensor. If the temperature is above a certain limit, the ECM will drive the engine bay fan for 8 minutes, and will then power down. If the engine bay temperature is below the limit the ECM will power down after 10 seconds. Engine compartment ambient air temperature sensor The ECM monitors the engine compartment temperature using the ambient air temperature sensor. When the temperature exceeds a certain limit, the engine bay fan relay is energised to run the fan. If the temperature continues to rise, and exceeds another higher limit, the engine bay warning lamp (in the instrument pack) is illuminated. If the ambient air temperature sensor fails, the engine bay fan will run while the ignition is on and the warning lamp will be permanently lit.
1. Air cleaner element
2. Throttle disc
3. Idle air control valve
4. Inlet manifold
5. Injector
6. Evaporative emission cannister, purge valve
7. Evaporative emission cannister
8. Engine Control Module (ECM)
9. Fuel trap - green connection to ECM
Intake air is drawn into the throttle body through an air filter element. Incorporated in the throttle body are the throttle disc and the throttle position sensor. Air passes from the throttle body to the inlet manifold where it is mixed with fuel injected by the injectors before the mixture is drawn into the combustion chamber. Inlet manifold depression is measured via a hose, by the MAP sensor which is incorporated in the ECM. A signal from the MAP sensor is used by the ECM to calculate the amount of fuel delivered by the injectors.