Chapter 5 Part B: Ignition system Contents DIS module - testing, removal and refitting . .... .......... . . .. 3 Ignition system - testing .... .... .. .. ... ..... . . ......... .. . 2 Engine management system check ... .. .. . ..... . . . See Chapter 1 Knock control system - general information . . . . . . . . . . . . . . . . . .. 4 General information . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Knock control system components - removal and refitting .. .... . 5 Ignition HT system check ... . .. . . .. .. . . . . . ... .. .. See Chapter 1 Spark plug check and renewal . ..... .. . . .. .... . ... See Chapter 1

Degrees of difficulty Easy, suitable for novice with little experience

~ Fairiy easy, suitable ~ ~ for beginner with ~

Fairiy difficult, ~ suitable for competent ~ DIY mechanic ~

Difficult, suitable for ~ experienced DIY ~

Very difficult, ~ suitable for expert DIY ~ or professional ~ ~ some experience ~ mechanic ~

Specifications General System type .... . . . . . .. .. ... .. . . .... . ..... .... . . . . .. .. . . . . Distributorless ignition system (DIS) System application:

SOHC engines .. .... . . .... . ...... . . . .......... . .. . ..... . DOHC engines:

1.0 and 1.2 litre engines . ..... ... . .. . .. . . .. .... .. ... .. . . . 1.4 and 1.6 litre engines ... . .. . . ... . . .... . . .. • . .. . . .. .. . .

GM Multec

Bosch Motronic M 1 .5.5 GM Multec

Location of No 1 cylinder . . .. ... . .. . ... . . . .. .. ... . ... ....... . Timing belt or timing chain end of engine Firing order:

All except 1.0 litre engines . . .. ... . .......... . ... . . ... .. . . . . 1-3-4-2 1.0 litre engines ....... . .... ... . . . . . .•. ... .. . ... .. . .. .. . .. 1-2-3

Torque wrench settings Nm DIS module-to-mounting plate bolts .. .. .... .. ..... ... . .... .. . . 8 DIS module mounting plate-to-camshaft housing bolts ...... .. . .. . 12 Knock sensor body to cylinder block . . . . . . . . . . .. . . . ........ .. . . 13 Knock sensor retaining bolt ... ...... . . .. .. .. . . .. .. ... . . . .. . . . 20 Spark plugs .. . .. . . .. . .. . .. . . ....... ..... . ... . . .. . .... .. .. . 25

1 General information and precautions

Ignition system function The ignition system is responsible for

igniting the air/fuel mixture in each cylinder at the correct moment, in relation to engine speed and load.

The ignition system is based on feeding

low-tension voltage from the battery to the coil, where it is converted into high-tension voltage. The high-tension voltage is powerful enough to jump the spark plug gap in the cyl inders many times a second under high compression pressures, providing that the system is in good condition.

The low-tension (or primary) circuit consists of the following: a) The battery. b) The lead to the ignition switch. c) The leads from the ignition switch to the

Ibf ft 6 9 10 15 18

DIS module, to the electronic control unit, and to the low-tension coil windings (integral with the DIS module).

The high-tension (or secondary) circuit consists of the following: a) The high-tension (HT) coil windings

(integral with the DIS module). b) The HT leads (or module connectors)

from the DIS module to the spark plugs. c) The spark plugs. The system functions in the following

manner. Current flowing through the low-

58-2 Ignition system

tension coi l windings produces a magnetic field around the high-tension windings. The electronic control unit produces a signal used to switch off the low-tension circuit.

The subsequent collapse of the magnetic field over the high-tension windings produces a high-tension voltage, which is then fed directly from the coil to the relevant spark plug(s) . The low-tension circuit is automatically switched on again by the electronic control unit, to allow the magnetic field to build up again before the firing of the next spark plug(s). The ignition is advanced and retarded automatically, to ensure that the spark occurs at the correct instant in relation to the engine speed and load.

Multec DIS (Distributorless Ignition System)

This system is fitted to models with 1.2 SOHC, 1.4 and 1.6 litre engines.

The system is under the overall control of the Multec electronic control unit, which controls both the ignition and fuel injection systems. The system comprises various sensors (whose inputs also provide data to control the fuel injection system) , and the Multec electronic control unit, in addition to the DIS module and spark plugs. Details of the system sensors and the electronic control unit are given in Chapter 4B.

The DIS module is attached to the camshaft housing in the position normally occupied by the distributor, and consists of two ignition coils and an electronic control module, housed in a common casing. Each ignition coil supplies two spark plugs with HT voltage - thus, one spark is provided in a cylinder with its piston on the compression stroke, and one in a cylinder with its piston on the exhaust stroke. This results in a 'wasted spark' being supplied to one cylinder during each ignition cycle, but this has no detrimental effect. This system has the advantage that there are no moving parts - therefore there is no wear, and the system is largely maintenance-free.

Information on crankshaft position, and engine speed and load is supplied to the Multec electronic control unit via inputs from the various system sensors (see Chapter 4B).

The electronic control unit selects the optimum ignition advance setting based on the information received from the various sensors. The degree of advance can thus be constantly varied to suit the prevailing engine operating conditions.

Motronic M 1.5.5 DIS (Distributorless Ignition System)

This system is fitted to models with 1.0 and 1.2 litre DOHC engines (see Vehicle identification for details of engine code locations).

The system is under the overall control of the Motronic electronic control unit, which controls both the ignition and fuel injection systems. The system comprises various sensors (whose inputs also provide data to

control the fuel injection system), and the Motronic electronic control unit, in addition to the DIS module and spark plugs. Details of the system sensors and the electronic control unit are given in Chapter 4A.

The DIS module is located centrally on the camshaft cover directly over the spark plugs. The module contains a separate ignition coil for each cylinder which is integral with the spark plug cap, and connected directly to the relevant spark plug. This removes the need for any HT leads connecting the coils to the plugs.

Information on crankshaft position, cylinder identification , and engine speed and load is supplied to the Motronic electronic control unit via inputs from the various system sensors (see Chapter 4A).

The electronic control unit selects the optimum ignition advance setting based on the information received from the various sensors, and fires the relevant ignition coil accordingly. The degree of advance can thus be constantly varied to suit the prevailing engine operating conditions.

2 Ignition system - testing ~

~ ~

A Warning: The HT voltage

, generated by an electronic • ignition system is extremely high

and, in certain circumstances, could prove fatal. Take care to avoid receiving electric shocks from the HT side of the ignition system. Do not handle HT leads, or touch the DIS module, when the engine is running. If tracing faults in the HT circuit, use well-insulated tools to manipulate live leads. Persons with surgically-implanted cardiac pacemaker devices should keep well clear of the ignition circuits, components and test equipment.

General 1 The components of the DIS system are normally very reliable; most faults are far more likely to be due to loose or dirty connections, or to 'tracking' of HT voltage due to dirt, dampness or damaged insulation, than to the failure of any of the system components. Always check all wiring thoroughly before condemning an electrical component, and work methodically to eliminate all other possibilities before deciding that a particular component is faulty. 2 The practice of checking for a spark by holding the live end of an HT lead a short distance away from the engine is not recommended - not only is there a high risk of a powerful electric shock, but the DIS module or electronic control unit may be damaged. 3 Extreme care should be taken if attempts are to be made to test the system, as the electronic control unit is very sensitive and, if damaged, may prove very costly to renew.

4 Unless the correct special test equipment is available, entrust testing and fault diagnosis to a Vauxhall/Opel dealer. It is far better to pay the labour charges involved in having the vehicle checked by someone suitably qualified, than to risk damage to the system or yourself. The engine management system has a self-diagnostic function, and any problems with the system are stored as fault codes, which can be read using suitable specialist diagnostic equipment. Brief details are given in Chapters 4A and 4B.

Engine fails to start 5 If the engine either will not turn over at all, or only turns over very slowly, check the battery and starter motor. Connect a voltmeter across the battery terminals (meter positive probe to battery positive terminal). Disconnect the wiring plug from the DIS module, then note the voltage reading obtained while tuming over the engine on the starter for a few seconds. If the reading obtained is less than approximately 8 volts, check the battery, starter motor and charging system (see Chapter SA). 6 Testing of the ignition L T and HT circuits can only be carried out safely and effectively using special test equipment, and should be entrusted to a Vauxhall/Opel dealer.

Engine misfires 7 Misfires are usually the result of partial or temporary failures in the system components, and the possible causes are too numerous to be eliminated without the use of special test equipment. The ignition system wiring and the spark plugs can be checked for signs of obvious faults as described in the following paragraphs, but if these checks do not reveal the source of the problem, take the vehicle to a Vauxhall/Opel dealer, who will be able to test the full engine management system using the appropriate equipment. 8 An irregular misfire suggests a loose or dirty connection. With the ignition switched off, check the security and condition of the DIS module wiring, and the HT leads (where applicable). 9 Regular misfiring is most likely to be due to a fault in the HT leads (where applicable) or spark plugs. Check that the HT leads are clean and dry. Check the leads themselves and the spark plugs (by substitution if necessary). Renew the spark plugs as a matter of course if there is any doubt about their condition (refer to Chapter 1 for details of checking spark plugs).

3 DIS module - ~ testing, removal and refitting §

~

Testing 1 Testing of the DIS module can only be carried out safely, and without the risk of

3.4 Disconnecting the DIS module wiring plug - SOHC engine

damage to the module, using the appropriate special test equipment. Testing should therefore be entrusted to a Vauxhall/Opel dealer.

Removal

1.2 SOHC, 1.4 and 1.6 litre engines 2 The DIS module is mounted on the left­hand end of the camshaft housing. For improved access on DOHC engines, remove the secondary air injection pump assembly as described in Chapter 4C. 3 Disconnect the battery negative terminal (refer to Disconnecting the battery in the Reference Chapter). 4 Disconnect the module wiring plug (see illustration). 5 Disconnect the HT leads from the module, noting their locations to ensure correct refitting . The HT lead cylinder numbers are stamped into the module casing (see illustration). 6 Unscrew the three Torx-type securing screws, and remove the module from its mounting plate.

1.0 and 1.2 litre DOHC engines 7 The DIS module is mounted in the centre of the camshaft cover, directly above the spark plugs. 8 Disconnect the battery negative terminal (refer to Disconnecting the battery in the Reference Chapter). 9 Release the DIS module cover and remove

3.10 DIS module wiring plug -1.2 litre DOHCengine

3.5 HT lead cylinder number identification marks (1) and DIS module securing

screws (2) - SOHC engine

it toward the transmission end of the engine (see illustration). 10 Disconnect the module wiring plug (see illustration). 11 Undo the two module retaining screws, then lift the DIS module upwards and off the spark plugs (see illustration). If necessary, the module may be very carefu lly eased upwards using a screwdriver. Take care to keep the module level as it is released from the spark plugs to avoid damage to the module connectors and the upper ceramic part of the spark plugs.

Refitting 12 Refitting is a reversal of removal.

4 Knock control system -general information

Note: For details of engine code locations, refer to 'Vehicle identification'.

The knock control system forms part of the ignition system, and allows the ignition timing to be advanced to the point at which 'knocking' or 'pre-ignition' is about to occur. This contributes to improved engine efficiency and reduced exhaust emission levels, as it allows the engine to run as close as possible to the 'knock limit' (the point at which 'pre­ignition' or 'pinking' occurs) without the risk of engine damage. The ignition timing is set to a

3.11 Undo the two retaining screws, then lift the DIS module upwards and off the

spark plugs - 1.2 litre DOHC engine

Ignition system 5S-3

3.9 Release the DIS module cover and remove it toward the transmission end of

the engine - 1.2 litre DOHC engine

pre-determined value (stored in the memory of the engine management electronic control unit), which is very close to the knock limit for the engine. Due to slight changes in the combustion process during varying engine operating conditions, and possible slight fuel irregularities, engine knock may occur, and this is detected and controlled by the knock control system.

The system comprises a knock sensor, a separate knock module (X 12 SZ and X 14 SZ engines only), and the Multec or Motronic engine management electronic control unit (see Chapter 4A or 48). On all engines except X 12 SZ and X 14 SZ the knock module is an integral part of the engine management electronic control unit (ECU).

The knock sensor is located on the cylinder block, and contains a piezo-electric crystal , which has a resonance frequency which corresponds to the engine knock frequency. Mechanical vibrations in the cylinder block are converted by the sensor into an electrical signal. The output signal provided by the sensor increases with an increase in the vibrations in the cylinder block. If the signal increases beyond a preset limit, the sensor indicates the onset of 'knock' to the knock module.

The knock module acts as a signal processor, and modifies the signal produced by the sensor before providing an output to the ECU.

The ECU processes the signals received from the knock module, and retards the ignition timing to prevent knock. From the signals provided by other engine management sensors (see Chapter 4A or 48), the ECU can determine the cylinder which fired most recently before the knocking occurred, and hence can trace the knocking to that particular cylinder. The ignition timing for the particular cylinder concerned is thus retarded ('selective knock control') , giving independent ignition timing control over all cylinders. Once knocking has been detected and prevented, the ignition timing is progressively advanced to the pre-determined value, or until knocking recurs. The system processes signals many times per second , and is able to react to changes sufficiently quickly to prevent engine

5S-4 Ignition system

damage, with no perceptible effect on engine performance.

If the system develops a fault, the ignition timing is automatically retarded by a pre­determined amount as a safety precaution, and this may be detected as a slight reduction in engine performance.

5 Knock control system ~ components - removal and ~ refitting ~

Knock sensor Note: When refitting the sensor, to ensure correct operation, it is essential to tighten the sensor to the specified torque. On engines where the sensor body is screwed into the cylinder block (rather than being secured by a retaining bolt)Vauxhal/lOpel specify the use of tool KM-728 to achieve this. If this tool is not available, it will be necessary to obtain or improvise a suitable alternative.

Removal 1 The sensor is located centrally at the rear of the cylinder block, below the inlet manifold (see illustration). 2 Disconnect the battery negative terminal

5.5b Knock sensor wiring connector location - SOHC engine

5.1 Knock sensor location (arrowed) -viewed from underneath vehicle -

SOHC engine

(refer to Disconnecting the battery in the Reference Chapter). 3 Access is most easily obtained from underneath the vehicle. Apply the hand brake, then jack up the front of the vehicle and support securely on axle stands (see Jacking and vehicle support). 4 On 1.0 and 1.2 litre DOHC engines, unbolt the inlet manifold support bracket from the manifold and cylinder block. 5 On 1.2 SOHC, 1.4 and 1.6 litre engines , separate the two halves of the sensor wiring connector, which is located on a bracket

5.11 Disconnecting the wiring plug from the knock control system module -

1.2 litre SOHC engine

5.5a Separating the two halves of the knock sensor wiring connector -

SOHC engine

either next to the left-hand engine lifting bracket, or behind the inlet manifold (see illustrations). 6 On 1.0 and 1.2 litre DOHC engines, disconnect the wiring connector from the knock sensor body. 7 Undo the sensor retaining bolt, or unscrew the sensor itself and remove it from the cylinder block.

Refitting 8 Refitting is a reversal of removal, but ensure that the sensor body itself, or its retaining bolt is tightened to the specified torque, bearing in mind the note at the beginning of this Section.

Knock control system module Removal 9 The module is located on a bracket attached to the left-hand side of the engine compartment, in front of the suspension strut turret. 10 Disconnect the battery negative terminal (refer to Disconnecting the battery in the Reference Chapter). 11 Disconnect the module wiring plug (see illustration) . 12 Remove the two securing screws, and withdraw the module from its bracket. Refitting 13 Refitting is a reversal of removal.