Engine Overview - Z 24 XE Opel Antara I

Introduction

The Z 24 XE engine is included in the engine range for the introduction of the MY 2007 Antara.

The Z 24 XE is a family II type engine that conforms to Euro IV exhaust emission regulations.

View of the Z 24 Xe Engine

Engine Compartment - Component Location

The main engine components, relative to their location in the engine compartment are shown below.

General Description

The engine has an aluminium alloy cylinder head which sits on top of the cylinder block, and houses dual overhead camshafts. The camshafts are identical in construction and each operate the intake and exhaust valves.

The camshafts rest in journals which contain drilled oil passages. This allows the journals to be lubricated when oil is pumped to the camshafts.

The cylinder head contains drain holes whereby the oil can return to the oil pan.

The oil pump is responsible drawing oil from the oil pan to lubricate the various parts of the engine. An oil strainer is mounted before the inlet of the oil pump to remove impurities which could clog or damage the oil pump or other engine components.

Oil is passed through the oil filter before being fed through two paths to lubricate the cylinder block, cylinder head and their component parts.

The cast aluminium oil pan and the cylinder block make up the crankcase, and house the crankshaft. Oil holes running through the centre of the crankshaft, supply oil to the connecting rods, bearings, pistons, and the other components.

The oil pressure regulator prevents too much oil from entering the engine lubrication passages at high engine speeds.

A reinforced rubber timing belt coordinates the dual overhead camshafts (at the top) and the crankshaft (at the bottom) to keep them synchronized. The belt and the pulleys are toothed so that no slippage occurs between them.

The engine uses cross-flow intake and exhaust ports. The intake manifold possesses four independent long ports and has a has a throttle valve body fixed to the top of the manifold.

A single four port exhaust manifold is used to direct exhaust gases out of the combustion chambers with a minimum amount of back pressure.

The exhaust gas recirculation (EGR) valve is attached to the end of the cylinder head via an EGR adapter.

The EGR valve lowers nitrogen oxide (NOX) emission levels caused by high combustion temperatures, by recirculating small amounts of exhaust gas into the intake manifold to ease the temperature.

Z 24 Xe Torque and Output Curve

Engine Controls

The engine control system for the Z 24 XE uses the BOSCH ME 7.9.9 engine control module (ECM) at it's core to control all engine operations. The ECM uses information from the engine sensors to effectively control the fuel and exhaust systems, and is connected to the other on board control modules via the CAN bus.

The ECM, located in the engine compartment next to the battery, constantly monitors data from various sensors and other inputs, to assure optimal driveability and economy whilst guaranteeing minimum exhaust emissions. The unit performs continuous diagnostic tests on the system to insure that the engine is operating at its most efficient.

CAN Bus

The CAN bus is a series of data communication buses that allow the on board electronic control modules to communicate with each other, or, with a diagnostic tester.

The CAN bus allows the control modules to access information from each other, enabling them to work together as a functional unit and also coordinate their own operations more efficiently. Other vehicle components such as actuators, sensors and electric motors are connected to the control modules using conventional wiring.

The CAN bus supports three types of buses; high speed (HSCAN), mid speed (MSCAN) and low speed (LSCAN).

The HSCAN is used for communicating real time data such as engine torque and steering angle, while the MSCAN is typically used for infotainment display and navigation systems.

LSCAN is the only CAN bus that is able to communicate with ignition turned off, so as to enable system functions such as remote controlled central door locking and anti theft systems.

Using the data buses for communication between various control modules has several advantages over using separate wires.

The main advantages are:

• Fewer wires in harnesses and fewer plug-in terminals on the control modules contribute to a considerable weight reduction
• More efficient data exchange between the various control modules
• Improved reliability and serviceability

Diagnostic Trouble Codes

Diagnostic trouble codes (DTC's) are stored on the ECM when a malfunction in the system is detected. For each DTC, a code is allocated to signify whether the problem is an emissions related or non-emissions related fault.

When a malfunction is detected by the ECM, one of two warning lamps in the instrument panel light up. These are, the malfunction indicator lamp (MIL) and the service vehicle soon (SVS) lamp. The MIL indicates that there is an emissions related fault, while the SVS lamp indicates a non-emissions related fault. The MIL blinks continuously in the event of a severe misfire. The vehicle's electronic system will switch to an emergency running program.

Data Link Connector

The data link connector (DLC) is located under the instrument panel on the driver's side, and provides a means of accessing data from the ECM for diagnosis.

The TECH 2 diagnostic tool can be connected to the DLC to identify DTC's that have been stored by the ECM. TECH 2 can also clear stored DTC's, perform output control tests and read serial data.

• Service: Refer to the trouble code diagnosis in the service manual for the descriptions of the DTC's.

Control Systems

The direct ignition system is a distributorless system, so each spark plug is supplied with ignition energy directly from the ignition coil. The crankshaft position sensor information and RPM are used to establish the correct ignition timing and injection pulses for starting the engine. The ECM determines the correct electronic spark timing to activate the ignition coil, and supplies the spark to the spark plugs.

The throttle actuator control system uses accelerator pedal position (APP) sensors and throttle position (TP) sensors to establish a connection between the accelerator pedal and the throttle, thus, eliminating the requirement for a mechanical link.

The two APP sensors located in the accelerator pedal, give the actual position of the pedal to the ECM. The ECM directly controls the opening and closing of the throttle valve depending on the accelerator pedal position and several other inputs.

Two TP sensors and an actuator are integrated into the throttle valve housing. The actuator is able to change the position of the throttle valve while the TP sensors send the positional information to the ECM. The ECM requires this information to alter the air/fuel mixture in the engine.

The ECM uses front (H2OS1) and rear (H2OS2) heated oxygen sensors to adjust and maintain desired engine air/fuel mixtures to better control exhaust emissions and fuel economy.

The H2OS1 is located below the exhaust manifold on the exhaust pipe, and used as the primary measuring device for the fuel control system, to determine whether the engine is running too rich (excessive fuel) or too lean (too little fuel). The H2OS1 is constantly comparing the levels of oxygen inside the exhaust manifold to the levels outside the engine. If the H2OS1 detects that the levels of oxygen in the manifold are too high or too low, a signal is sent to the ECM. The ECM will then alter the air/fuel ratio to the engine accordingly by controlling the fuel injectors.

The H2OS2 is located in the exhaust system after the catalytic converter. This sensor is used to check the performance of the converter and may also be used to aid in adjusting the engine air/fuel ratio. Achieving the correct air/fuel ratio (14.7 parts air to 1 part fuel) is also essential for the operation of the catalytic converter to effectively minimize emissions.

The H2OS are functional when they are heated to a sufficient temperature and will operate in a closed loop mode. The closed loop mode allows the ECM the receive information from the H2OS only, to adjust the air/fuel ratio. An open loop mode is also used by the ECM when the engine is first started and the H2OS are not ready. The open loop mode will determine the air/fuel ratio based upon on the engine coolant temperature (ECT) sensor and the manifold absolute pressure (MAP) sensor.

Emission Control Systems

The evaporative emission control (EVAP) system is designed to store and dispose of fuel vapours created in the fuel system and prevent them being released into the atmosphere. The EVAP system consists of a canister, containing a carbon element and a purge solenoid that is connected to the ECM.

The EVAP canister is located under the vehicle in front of the fuel tank, and stores fuel vapours from the fuel tank in the carbon element. The ECM monitors various air and fuel sensors to determine when the canister is to be purged. The ECM activates the EVAP purge solenoid valve allowing intake vacuum to draw the fuel vapours into the engine.

The exhaust gas recirculation (EGR) system is designed to reduce the amount of oxides of nitrogen (NOx) created by the engine during operating periods that usually result in high combustion temperatures.

The EGR valve allows small amounts of exhaust gas to be recirculated back into the intake manifold with incoming air, thus reducing combustion temperature and pressure, and lowering the output of NOx.

The purpose of the positive crankcase ventilation (PCV) system is to remove the potentially damaging vapours that build up in the crankcase. The vapours are re-used by mixing them with air supplied to the crankcase from the air cleaner. The combined gases are then drawn from the crankcase by the PCV vacuum hose and fed into the intake manifold.

Engine Sensors

The intake air temperature (IAT) sensor is a thermistor type (a resistor which alters its voltage based on temperature) and is attached to the air cleaner outlet hose.

The ECM determines the air temperature in the manifold by measuring the change in voltage from the IAT sensor.

The engine coolant temperature (ECT) sensor is a thermistor type and is required by ECM functions such as fuel injection and ignition timing. The ECT sensor is fixed to the cylinder block and accesses the engine coolant passage.

The manifold absolute pressure (MAP) sensor uses the ECM to monitor the pressure in the intake manifold that is created by engine load. The intake manifold pressure is used by the ECM to calculate various engine functions such as fuel injection and ignition timing to improve performance and emissions. The ECM also uses the MAP sensor to calculate barometric pressure, thus, allowing the vehicle to function efficiently at altitude.

The knock sensor is installed on the engine cylinder block to detect abnormal knocking in the engine. The ECM monitors the voltage signal from the sensor and alters the ignition timing to eliminate the knock.

The camshaft position sensor is located behind the cam sprocket and detects the camshaft rotation speed. The sensor is used by the ECM to trigger the fuel injectors in the correct sequence. As the engine rotates the sensor will signal to the ECM that cylinder number one is approaching top dead centre and the timing of the injection pulse can be determined.

With the aid of the magnetic crankshaft position sensor, the ECM can determine the orientation of the crankshaft at all times. The sensor is attached to the side of the engine cylinder block and operates in conjunction with a 58 slot reluctor wheel on the crankshaft. The ECM receives voltage signals from the sensor to ascertain the actual position of the crankshaft. The ECM uses the information from the sensor to calculate ignition timing and injection pulses to send to the ignition coils and fuel injectors.