Ford Workshop Service and Repair Manuals

Thanks to the continuous development of new technologies in recent years, it has become possible to convert the harmful pollutants hydrocarbon (HC), carbon monoxide (CO) and nitrogen oxides (NOx), which are all contained in exhaust gas emissions, into safe emissions.

The key factor in this success has been the use of 3-way catalytic converters together with electronically controlled fuel injection. The continued development of fuel injection systems has brought ever improving results, contributing to further reductions of exhaust gas emissions.

However, in recent years the CO2 emissions have become an increasingly serious problem.

CO2 is one of the factors which contributes to the so-called greenhouse effect.

Demands to slow down this greenhouse effect have in turn resulted in demands to reduce CO2 emissions.

With the number of car journeys increasing across the globe, the only way to reduce CO2 emissions is to reduce fuel consumption.

Reduction of fuel consumption and exhaust emission standards

Various measures (e.g. exhaust gas recirculation) have already been put in place to achieve a significant reduction of fuel consumption.

As fuel consumption is directly linked to exhaust gas emissions, the necessity to meet the increasingly more stringent statutory exhaust emissions limits represents a key boundary condition.

From indirect injection to direct injection: In terms of meeting future exhaust emissions regulations, indirect injection technology (intake manifold injection) has been taken about as far as it can go.

Direct petrol injection

The technology of direct petrol injection offers a further great potential for savings. With this technology, fuel consumption can be reduced by 10 - 15 %. This savings potential can be increased by approximately a further 3% by combining the direct petrol injection with a thermal management system (electrically heated thermostat).

Advantages from direct diesel injection

High-pressure direct diesel injection has made diesel engines desirable again. The old-style diesel engines, characterised by their dull and frugal nature and an unmistakeably harsh combustion noise, have now evolved into powerful and even more frugal engines which are quiet enough to be accepted even at the top end of the market.

This beneficial technology of high-pressure direct diesel injection is now also being used by Ford for high-pressure direct petrol injection.

Operating modes

Stratified mode and homogeneous mode

In order to ensure that the best possible use is made of the fuel under all operating conditions, the engine management employs a total of three operating modes. These are as follows:

• Stratified mode,
• Homogeneous mode,
• Homogeneous-stratified mode.

The most important feature here is the stratified mode, as it offers the key advantage in terms of consumption and thus lowering of CO2 emissions.

In the lower torque band at engine speeds of up to around 3000 rev/min, with low engine loads and a coolant temperature above 60 °C the engine is operated in stratified mode.

The homogeneous mode is realised by means of double injection and is only used during the warm-up phase of the pre-catalytic converter.

Stratified mode

In stratified mode the throttle valve is almost completely open. "Almost" means here that the throttle valve is opened far enough to still leave enough remaining vacuum in the intake manifold for precise control of the Evaporative Emission (EVAP) system and the Exhaust Gas Recirculation (EGR) .

In stratified mode the swirl valve in the intake manifold is closed. Fresh air (possibly mixed with exhaust gas) is sucked in through the opened intake valve in response to the downward motion of the piston. At the same time the throttle valve is wide open and there is a large intake manifold vacuum .

A calculated swirl is introduced to the air as a result of the position of the swirl valves, and the air is then compressed in this state.

The fuel is not injected into the combustion chamber until just before the ignition point.

The formation of a combustible air/fuel mixture cloud plays a pivotal role in the stratified mode. The mixture cloud is formed accordingly as a result of the shape of the piston and the layout of the intake geometry.

The swirl motion transports the mixture cloud, which only fills a small part of the combustion chamber, to the spark plug.

As the injection timing is so late the mixture is not distributed throughout the entire combustion chamber.

The combustion therefore also only takes place in this smaller part of the combustion chamber. The flame front does not reach the walls around the entire circumference of the cylinder, as a result of which the thermal losses are kept low.

In this operating mode there is a large surplus of air, i.e. lambda > 1. The fuel/air ratio can be between 1:30 and 1:40 in stratified mode.

However, with such a large surplus of air the NOx emissions are very high. With careful exhaust gas recirculation and corresponding post-treatment of the exhaust gas it is nonetheless possible to reduce the NOx emissions to a minimum.

The stratified mode is limited by the variables engine speed and torque.

If the engine torque is too high then soot is produced in small regions which are fuel-rich (in a similar fashion to diesel engines). If the engine speed is too high then the stratification of the cylinder charge and the orderly transportation of the mixture to the spark plug can no longer be maintained because of excessive turbulence.

Conclusion: Stratified mode reduces fuel consumption by up to 20% as a result of reduced losses in the charge exchange process and reduced thermal losses at the walls of the cylinder.

Homogeneous mode

Under high engine loads or in full-load operation a large quantity of fuel is required to generate the required power. This means that the air/fuel mixture needs to be in the region of approximately lambda = 1.

In terms of the distribution of the mixture and the combustion process, the homogeneous mode is comparable to the combustion behaviour of a multi-point injection engine.

In homogeneous mode the swirl valves are fully opened above a certain engine speed threshold (depending on the engine load). This makes the full flow cross-section available in order to achieve a greater cylinder charge.

In order to ensure that there is enough time for the mixture to form, the fuel needs to be injected as early as possible.

To achieve this, fuel injection already takes place during the intake stroke in homogeneous mode.

The early timing of the injection ensures that the mixture is well formed even without increased movement of the charge.

During the relatively long mixture formation time the air and the fuel form a homogeneous mixture which evenly fills the entire combustion chamber.

In homogeneous mode the air intake is regulated by the electronic throttle valve. The mass air flow is therefore regulated by the position of the throttle valve.

The homogeneous mode can be used across the entire map range and guarantees low exhaust gas emissions in conjunction with the 3-way catalytic converter.

Homogeneous-stratified mode

The homogeneous-stratified mode is only used during the warm-up phase to heat up the catalytic converter assembly.

This operating mode is realised by means of double injection.

In this operating mode the first injection takes place during the intake stroke, as a result of which a homogeneous mixture is produced.

The second injection during the compression stroke is used to enrich the mixture enough to generate a high combustion temperature, therefore enabling the 3-way catalytic converter to reach its operating temperature within a very short time.

The swirl valves are closed in homogeneous-stratified mode.

Torque, power output and technical data and specifications

Torque and power output

Technical data and specifications

Cylinder head

Camshafts

The camshafts are made of solid quenched cast iron.

The exhaust camshaft runs on five bearings and the intake camshaft on six bearings.

The reason for the sixth bearing on the intake camshaft is the extension of the intake camshaft at the transmission end.

The extended end has two additional cams (offset to each other by 180°) which are used to drive the high-pressure fuel pump.

The front face of the additional bearing cap is also used as part of the flange for the high-pressure pump adapter.

The additional bearing cap has oil ducts on its inside, which are used to lubricate the cam drive of the high-pressure pump with engine oil.

The exhaust camshaft is equipped with a cylinder recognition sensor wheel for the PCM.

Note: A new special tool is required to adjust the camshaft setting as a result of the extended intake camshaft.

• Adjusting Tool 303-1061

Adapter for the high-pressure pump

An adapter is provided between the cylinder head (intake camshaft) and the high-pressure pump for mounting of the high-pressure pump.

A gasket seals between the adapter for the high-pressure pump and the flange on the cylinder head.

The guide sleeves are inserted into the flange on the cylinder head. They guarantee a precise fit of the high-pressure pump adapter, eliminating the need for adjustments.

Cylinder block

Piston

A completely new piston design has been developed for the direct petrol injection on the 1.8L Duratec SCi.

The piston is equipped with a piston recess for stabilisation of an ignitable mixture in stratified mode.

This is used together with the geometry of the intake path to optimise the transport of the intake air and the injected fuel to the spark plug in stratified mode.

The combustion chamber is enlarged accordingly by the piston recess. In order to still achieve the desired compression ratio of 11.3 : 1, the piston has been finished in such a way that a compression surface is formed on the exhaust side. This compression surface is used to compensate for the material missing from the piston recess and thus achieve the desired compression ratio.

Due to the very fine tolerances in the areas of the bearing clearances and the bearing shells, no repairs whatsoever are permitted on the crankshaft drive.