Toyota
Ford Kuga
 Service Manual
Electronic Engine Controls » Electronic Engine Controls (System Operation and Component Description)
System Operation

The engine is controlled by the PCM. For this purpose, the PCM uses information from the sensors, sender units and switches. In addition, the PCM receives information from other control modules via the CAN data bus. All the information is processed in the PCM and is used to control or regulate the different actuators.

These are:

  • the throttle control unit,
  • the fuel injectors,
  • the camshaft adjustment,
  • the boost control solenoid valve
  • and the ignition coils.

Some values are sent via the CAN databus to other systems.

The following functions are regulated or controlled by the PCM:

Starting process

Engine running

  • Fuel supply to the engine including lambda control
  • Ignition setting including knock control
  • Idle speed control
  • Boost pressure control
  • Valve timing via the camshaft adjuster for the intake and exhaust camshafts (including internal exhaust gas recirculation)

Refrigerant compressor (activation, deactivation and delivery)

EVAP purge valve

Charging system

Fuel is supplied to the engine via a sequential multi-point injection system. Ignition is performed by a distributor-less ignition system with one ignition coil unit for each cylinder.

The PCM optimizes engine power and emissions at all times by processing the sensor signals and information received via the CAN databus and using these for open or closed loop control of the different variables.

The PCM contains part of the PATS (passive anti-theft system).

The PCM is supplied with battery voltage via a fuse in the BJB (battery junction box). This power supply is needed to ensure that saved data is not lost when the engine is switched off.

For other power supply requirements, the PCM switches on a relay in the BJB which is responsible for supplying power to the PCM and to some sensors and actuators. Each of these are protected by fuses in the BJB.

To guarantee optimum engine running at all times, the PCM has several adaptive (self-learning) functions. These adapt the output signals to changing circumstances, such as wear or system faults.

In some cases a faulty signal is replaced with a substitute value or limited. A substitute value can be calculated from other signals or it can be predefined by the PCM. The substitute value allows the vehicle to keep on running without the emission values changing unduly. Depending on the signal failure, the PCM operates in emergency mode. In this mode, the engine power and/or the engine speed is reduced to prevent further damage.

Depending on the faulty signal, a fault code is stored in the error memory of the PCM. These can be read out using IDS (Integrated Diagnostic System) via the DLC.

The PCM processes and evaluates the signals from the sensors. The following sensors send signals to the PCM:

  • CMP sensors
  • CKP sensor
  • MAF sensor
  • KS
  • ECT sensor
  • TP sensor
  • APP sensor
  • Broadband HO2S
  • Catalyst monitor sensor
  • MAPT sensor
  • Air conditioning (A/C) pressure sensor
  • Alternator
  • Fuel temperature and fuel pressure sensor
  • Engine oil level, temperature and quality sensor
  • Outside air temperature sensor

The following components receive signals from the PCM:

  • Powertrain Control Module relay
  • A/C clutch relay
  • injectors
  • Direct ignition coils
  • Cooling fan module
  • Throttle control unit
  • Camshaft adjuster solenoid valve
  • Starter Relay
  • EVAP purge valve
  • Alternator
  • Heating element - broadband HO2S
  • Catalyst monitor sensor heating element
  • FPDM
  • Wastegate control valve
  • Air conditioning compressor

The PCM receives the following signals via the CAN databus:

  • APP
  • CPP
  • BPP
  • Vehicle speed.
  • Refrigerant compressor request
  • PATS
  • Torque reduction request (stability assist module)
  • Cruise control request

The PCM sends the following signals via the CAN databus:

  • Fuel pump relay on/off
  • Engine speed
  • Warning lights on/off (MIL (malfunction indicator lamp), battery warning lamp)
  • PATS
  • ECT
  • Air conditioning pressure transducer
  • Outside air temperature

With the aid of the input and output signals listed above, the PCM controls / regulates engine starting, fuel injection and fuel pressure, ignition, boost pressure, camshaft adjustment, tank purging, the radiator fan and the refrigerant compressor.

Speed and TDC recording

The CKP uses the PCM sensor to record engine speed and detect 1st cylinder TDC (top dead center).

Speed and TDC recording

An additional sensor wheel for the CKP sensor is located on the flywheel. This has 60-2 teeth. The gaps between the teeth are required for detection of TDC. The CKP sensor works according to the induction principle and generates a sinusoidal signal voltage whose level and frequency are speed-dependent.

From the frequency of the signal the PCM calculates the engine speed. Each time the engine rotates, the double gap in the sensor wheel alters the sinusoidal oscillation that is generated; this helps the PCM to detect the TDC position of cylinder 1.

The signal from the CKP sensor is used to determine

  • the crankshaft position,
  • the engine speed,
  • the ignition timing,
  • the injection timing and
  • the adjustment angle of the VVT units.
Item Description
1 CKP sensor
2 Tooth pitch
3 Flywheel ring gear
4 Reference mark
5 Voltage (sinusoidal-like signal curve)
6 60-2 pulses per revolution of the crankshaft
7 Tooth center
8 Reference mark
9 Tooth pitch

The acceleration of the flywheel at each power stroke results in a change in the CKP signal.

During the power stroke, the combustion pressure acting on the piston causes an acceleration of the crankshaft and thus also of the flywheel. This is apparent in the voltage curve from slightly higher frequencies and amplitudes of the CKP signal.

Calculation of the ignition angle

Since propagation of the flame front in the air/fuel mixture always takes the same amount of time, the ignition of the air/fuel mixture has to take place earlier or later depending on the engine speed.

The higher the speed, the earlier ignition must occur. This ensures that maximum combustion pressure is achieved immediately after Top Dead Center and that maximum combustion pressure acts on the piston.

When starting the engine, ignition timing is determined by the CMP purely from the ignition map and information on camshaft position (CKP sensors) and crankshaft position (PCM sensor).

As soon as the engine is running, the following data are used as a basis for calculating the ignition angle:

  • the engine speed,
  • the engine load,
  • the coolant temperature and
  • the KS signal.

The ignition angle has a major impact on engine operation. It affects

  • engine performance
  • exhaust emissions
  • fuel consumption,
  • combustion knock behavior and
  • - engine temperature

The higher the engine load, i.e. the torque demand, the richer the air/fuel mixture, the longer the combustion period and the earlier the ignition.

The PCM calculates engine load using the MAF sensor signal, the throttle position and engine speed. This is done using ignition maps that are stored in the PCM. The ignition timing is adjusted according to the operating condition of the engine, for cold starting for example.

Ignition map

Ignition map

Item Description
1 Engine load.
2 Engine speed
3 Ignition angle

The ignition maps were calculated in a series of tests. Particular attention is paid to the emission behaviour, power and fuel consumption of the engine. The ignition map is stored in the data memory of the PCM.

By adjusting the ignition timing it is also possible to influence the engine speed to some extent without having to change the throttle valve position.

This has advantages for idling stabilization, as the engine speed and hence the engine torque respond far more quickly to a change in the ignition timing than to a change in the throttle valve position. The ignition timing also changes much more quickly.

To keep the ignition point as close as possible to the knock limit and so optimize the efficiency of the engine, two KS are installed in the engine, which pick up the mechanical vibrations of the engine and convert them into an electrical signal for the PCM.

Ignition map

Item Description
A Normal combustion
B Knocking combustion
1 Pressure characteristic in cylinder
2 Output signal from KS

The term "knocking" is used to describe combustion processes in which the flame front propagation speed reaches the speed of sound.

This can happen towards the end of combustion in particular, when unburnt air/fuel mixture on the combustion chamber walls self-ignites due to the increase in pressure following initiation of regular combustion. The resulting pressure peaks damage the pistons, cylinder head gasket and cylinder head.

The cylinder in which combustion knock is occurring is identified from the camshaft position (CMP sensors) and crankshaft position (CKP sensor) information.

If the PCM detects combustion knock, the ignition timing for the cylinder in question is gradually retarded for a few crankshaft revolutions until combustion knock stops. After that the ignition point is slowly returned to the calculated value. This facilitates individual cylinder ignition, which makes it possible for the engine to operate at optimum efficiency at the knock limit.

Engine fueling

Fuel is supplied by a non-return fuel system.

Fuel pressure and fuel delivery rate are regulated by the PCM with the aid of the FPDM. The fuel pump is supplied with a cycled voltage by the FPDM. By cycling the voltage, the fuel pump output can be steplessly adjusted. The fuel pressure can be steplessly regulated between 3 and 5 bar.

Adjusting the fuel pump output has the following advantages:

  • The fuel pump's power consumption is reduced, thereby reducing the load on the vehicle's power supply system.
  • The fuel pump's service life is increased.
  • Fuel pump noise is reduced.

Fuel pressure regulator

The PCM calculates the required fuel pressure based on the operating conditions. The PCM transmits a corresponding PWM signal to the FPDM. With the aid of this signal, the FPDM actuates the pump by sending, in turn, a PWM signal to the ground connection of the fuel pump.

The fuel pump can be steplessly regulated by varying the pulse width of the PWM signal.

The PCM continuously monitors the fuel pressure in the fuel rail by means of the fuel temperature/fuel pressure sensor. If the pressure deviates from the calculated value, the PCM adapts the PWM signal to the FPDM accordingly. Thus the fuel pressure levels out at approx. 4 bar.

For safety reasons, the PCM switches off fuel delivery if the SRS (supplemental restraint system) module detects a crash.

Regulation of injected fuel quantity

The electromagnetically controlled injectors dose and atomize the fuel. The quantity of injected fuel is regulated by the duration of actuation of the fuel injectors. The fuel injectors are either closed (not  actuated) or opened (actuated). Each cylinder has its own injector. The injection is accurately dosed and takes place at a time determined by the PCM.

Injection takes place immediately in front of the intake valves of the cylinder. The injectors are actuated ground side via end-stages integrated into the PCM and using the signal calculated by the engine management system. Power is supplied via the Powertrain Control Module relay in the BJB.

The injected fuel quantity depends on the opening time, the fuel pressure and the diameter of the nozzle holes.

The fuel metering is determined via open or closed-loop control.

The open control loop differs from the closed control loop in that the lambda control is deactivated.

The PCM switches from closed to open-loop control if the HO2S cools down to below 600C or fails, as well as when accelerating, coasting and at full load.

Regulation of injected fuel quantity via the PCM involves:

  • controlling the fuel pump,
  • calculating the required quantity of fuel for engine starting,
  • observance of the desired air/fuel ratio,
  • calculating air mass,
  • and calculating the fuel quantity for the different operating states and corresponding fuel adjustment measures.

Open loop control

Open loop control is used primarily for fuel injection, as long as the signals of the HO2S are not involved in the calculation of the PCM.

The two most important reasons that make it absolutely essential to run the engine without lambda control (open-loop control) are the following operating conditions:

  • Cold engine (starting, warm-up phase)
  • Full-load operation (WOT (wide open throttle))

Under these operating conditions the engine needs a rich air/fuel mixture with lambda values below λ = 1 in order to achieve optimum running or optimum performance.

It is possible to keep this unregulated range very small by using a broadband HO2S.

Closed-loop control

Closed loop control ensures strict control of exhaust emissions in conjunction with the TWC  (three-way catalytic converter) and economical fuel consumption. With closed loop control, the signals from the HO2S are analyzed by the PCM and the engine always runs in the optimum range of λ = 1.

In addition to the normal HO2S, the signal from the monitoring sensor for the catalytic converter is also included in the control. The lambda control is optimized on the basis of this data.

Certain factors such as wear, component tolerances or more minor defects such as air leaks in the intake system are compensated for by lambda control. If the deviation occurs for a longer period of time, this is recorded by the adaptive (self-learning) function of lambda control. In this instance, the entire map is shifted by the corresponding amount, to enable control to commence once again from the virtual baseline.

These adaptive settings are stored in the PCM and are also used in open-loop control conditions.

If the adaptive value is too high or too low, an error is stored in the fault memory of the PCM.

Oxygen sensor (HO2S) and catalyst monitor sensor

A broadband HO2S is used as the HO2S. The HO2S is located in front of the TWC. The catalyst monitor sensor is located in the center of the TWC so that it can detect any deterioration in the cleaning performance of the TWC more quickly.

The HO2S measures the residual amount of oxygen in the exhaust before the TWC.

The catalyst monitor sensor measures the amount of oxygen in the exhaust gas after or in the TWC.

Both the HO2S and the catalyst monitor sensor transmit these data to the PCM.

The broadband HO2S works at temperatures of between 650C and 900 C. If the temperature rises above 1000C, the oxygen sensor will be irreparably damaged.

To reach optimum operating temperature as quickly as possible, an electrically-heated oxygen sensor is installed. The heating also serves to maintain a suitable operating temperature while coasting, for example, when no hot gases are flowing past the oxygen sensor.

The heating element in the HO2S is a PTC (positive temperature coefficient) resistor. The heating element is supplied with battery voltage as soon as the Powertrain Control Module relay engages. The HO2S is earthed via the PCM. As the heating current is high when the element is cold, it is limited via PWM in the PCM until a certain current value is reached. The PCM then permanently connects the heating element to earth.

The catalyst monitor sensor is used by the PCM to measure the oxygen content in the exhaust gas in the TWC. If all the conditions for catalyst diagnostics are met, based on this information the PCM can check that the TWC is working satisfactorily. The information is also used to improve the air/fuel mixture adjustment.

The catalyst monitor sensor is similar in function to an HO2S. The signal transmitted by the catalyst monitor sensor changes sharply if the oxygen content in the exhaust gas changes. For this reason, catalyst monitor sensors are also called "jump lambda sensors".

Fuel tank purging

The EVAP purge valve is only actuated by the PCM if the coolant temperature is at least 60C.

Actuation is done ground side by means of a PWM signal. This makes it possible to have the full range of opening widths, from fully closed to fully open.

The PCM determines from the operating conditions when and how wide to open the EVAP tank purge valve. If the EVAP purge valve is opened, the engine sucks in ambient air through the activated charcoal in the evaporative emission canister as a result of the vacuum in the intake manifold. In this way the adsorbed hydrocarbons are led to the combustion chamber of the engine.

The EVAP tank purge valve is not actuated and system cleaning is interrupted if the engine switches to idle and/or a closed-loop control process is initiated.

Power (battery voltage) is supplied via the Powertrain Control Module relay in the BJB. The solenoid coil resistance is between 17 and 24 ohms at 20C.

Engine speed control

The APP sensor provides the PCM with information about the driver's request for acceleration.

The throttle control unit receives a corresponding input signal from the PCM. An electric motor then moves the throttle valve shaft by means of a set of gears. The position of the throttle is continuously recorded by the TP sensor. Information on throttle position is processed and monitored by the PCM.

The TP sensor comprises two potentiometers.

These work in opposite ways to each other. In one potentiometer, the resistance increases when the throttle is opened, in the other it decreases. This allows the operation of the potentiometers to be checked. The signal from the TP sensor is amplified in the lower range (idle to a quarter open) by the PCM to enable more precise control of the throttle in this range. This is necessary because the engine is very sensitive to changes in throttle angle in this throttle opening range.

With the throttle valve position kept constant, the ignition angle and the injected fuel quantity are then varied to meet the torque demands.

Depending on the operating state of the engine, a change in the position of the throttle flap may not be necessary when the APP sensor changes.

If a fault develops in the throttle control unit, a standby function is executed. This standby function allows a slight opening of the throttle flap, so that enough air passes through to allow limited engine operation. For this purpose, there is a throttle flap adjustment screw on the throttle housing. The return spring closes the throttle flap until the stop of the toothed segment touches the stop screw. In this way a defined throttle flap gap is formed for limp home mode.

The stop screw has a spring loaded pin, which holds the throttle flap open for limp home mode.

In normal operating mode, this spring loaded pin is pushed in by the force of the electric motor when the throttle flap must be closed past the limp home position (e.g. for idle speed control or overrun shutoff).

Oil monitoring

The engine does not have an oil pressure switch. The oil level and oil quality are calculated.

Calculating the engine oil level

The oil level is determined by continuous measurement of the capacitance (i.e. the ability to store an electrical charge) between the two capacitive elements of the engine oil level/temperature/quality sensor. The different oil levels cause the capacitance between the elements to change. The data are recorded by the PCM and converted into an oil level value. Temporary fluctuations in oil level are automatically filtered out by the PCM.

Calculating oil quality

The PCM calculates the oil quality from the oil level measurement and the oil temperature measured by the sensor, plus the engine speed and the average fuel consumption. The driver is informed about when an oil change is due.

Calculation of valve timing adjustment angle

The 2.5L Duratec (VI5) engine has two camshaft adjustment units which work independently of each other.

One camshaft adjustment solenoid is installed for each intake camshaft and exhaust camshaft.

This allows the PCM to continuously adjust the intake and exhaust-side camshaft adjustments independently of one another. The timing is adjusted by the PCM using curves; adjustment is primarily done as a function of engine load and engine speed.

In this way the engine performance is increased and internal exhaust gas recirculation is realized.

The advantages of camshaft adjustment are as follows:

  • Higher torque and improved torque characteristics
  • Reduced fuel consumption
  • Improved emissions performance

The camshaft adjustment solenoids are actuated by the PWM by means of a PCM signal.

Continuous adjustment of the camshafts by the PCM is achieved by means of the camshaft adjustment solenoids, the camshaft adjustment units and two CMP sensors. A defined quantity of engine is oil is supplied to or drained from the adjustment units via the camshaft adjustment solenoids. The existing EOP (engine oil pressure) is taken into account in the process. In this way the valve timings are adjusted according to the operating condition of the engine. The camshaft adjusters work according to the vane-cell principle.

On starting the engine, both camshafts are mechanically locked in their starting positions. The intake camshaft is in the maximum late position and the exhaust camshaft in the maximum early position.

Control is divided into four main areas:

  • Low engine speed and low load
  • Partial load
  • Low engine speed and high load
  • High engine speed and high load

At low engine speed and low load, the exhaust valves open early and the intake valves open late.

The result is reduced fuel consumption and more uniform idling.

At low engine speed and low load, the exhaust valves open early and the intake valves open late.

The result is reduced fuel consumption and more uniform idling.

In order to avoid a malfunction in the camshaft adjustment units at excessively low ambient or engine-oil temperatures, they are activated by the PCM with a time delay via the camshaft adjustment solenoids. The PCM receives the information required for this from the ECT sensor and the outside air temperature sensor.

When idling and during deceleration, the camshaft adjustment solenoids are activated repeatedly by the PCM in order to remove any dirt which may be on the bore holes and ring grooves.

Boost pressure control

Optimum regulation is achieved by means of an electronically-controlled solenoid valve, the boost control solenoid valve.

Refer to: Turbocharger (303-04 Fuel Charging and Controls - Turbocharger - 2.5L Duratec (147kW/200PS) - VI5, Description and Operation).

Starting process

The PCM enables the starting process when a key providing a valid code is read via the PATS.

Refer to: Starting System (303-06 Starting System - 2.5L Duratec (147kW/200PS) - VI5, Description and Operation).

Alternator control (Smart Charge)

The vehicle is fitted with a Smart Charging charge system.

In this system, the charge voltage is regulated by the PCM.

Refer to: Generator (414-02 Generator and Regulator, Description and Operation).

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