1994 FIAT PUNTO control system

4A*2 Fuel system -
single-point
petrol Injection models
6.13b ... and tho EVAP purge valve hose
14 Undo the two bolls securing the plastic nlet manifold upper section to the lower section. Release the spark plug HT lead from Ihe location groove in the manifold upper section, then lift the upper section, complete with throttle body, off the engine (see illustrations). Recover the O-nngs from the manifold ports. 16 Unscrew the two bolts securing the fuel rail assembly to the Inlet manifold lower section, inen carefully pull the injectors from ttie inlet manifold (see Illustration). Remove
tt>e
assembly from the engine and remove the injector lower O-ring seals. t& The injectors can be removed individually from the fuel rail by disconnecting the wiring connector, extracting the relevant metal clip
ano
easing the injector out of the rail. Remove themjector upper O-ring seals. 17 Check the electrical resistance of the tractor using a multimeter and compare it with the Specifications. Note: If a faulty Rector fc suspected, before condemning Wie
Rector,
it is worth trying the effect of one of m
proprietary
injector-cleaning treatments. Refitting
15 Refit the injectors and fuel rail by following tie removal procedure, In reverse, noting the Mowing points:
4} Re/few
the Injector O-ring seals, and
smear
them with a little Vaseline before assembling. Take care when fitting the
injectors
to the fuel rail and do not press
them
in further than required to fit the
retaining
clip otherwise the O-ring
seal may
be damaged.
6.14a Undo the inlet manifold upper section retaining bolts ... b) Ensure that the injector retaining clips are securely seated. c) Renew the sealing O-nngs fitted between the manifold upper and lower sections if in any doubt about their condition. d) Make sure the fuel supply and return hoses are correctly fitted as noted on removal. e) Check that all vacuum and electrical connections are remade correctly and securely. f) On completion check the fuel rail and injectors tor fuel leaks.
Fuel pressure regulator
Removal 19 Remove the resonator, air cleaner and inlet air ducts as described In Section 2. 20 Depressurise the fuel system as described In Section 9. 21 Disconnect the vacuum hose from the port on the side of the regulator. 22 Extract the retaining clip and pull the pressure regulator out of the fuel rail. 23 Remove the O-ring seal. Refitting 24 Refit the fuel pressure regulator by following the removal procedure in reverse, noting the following points: a) Renew the O-ring
seaJ
and smear it with a little Vaseline before assembling. b) When fitting the retaining clip, use a suitable socket or metal tube to press in the three anchorage points at the same time. c) Refit the vacuum hose securely.
Idle control stepper motor 25 The idle control stepper motor is an Integral part of the throttle body and cannot be individually renewed.
Throttle potentiometer 26 The throttle potentiometer Is an integral part of the throttle body and cannot be individually renewed.
Intake air temperature/pressure sensor
Removal
6.14b ... and lift off the manifold upper section and throttle body 28 Disconnect the sensor wiring connector, located on the right-hand side of the Inlet manifold upper section. 29 Undo the two screws and remove the sensor from the manifold. Refitting 30 Refitting is a reversal of the removal procedure. Coolant temperature sensor 31 Refer to Chapter 4A.
Crankshaft TDC sensor 32 Refer to Chapter 4A.
Electronic control unit (ECU)
Removal Note: 77?e engine management system has a learning capability which allows the ECU to store details of the engine's running characteristics in Its memory. This memory will be erased by the disconnection of the battery cables, with the result that the engine may idle roughly, or lack performance for a while, until the engine's characteristics are re-learnt. 33 The ECU (electronic control unit) is located on the right-hand inner wing panel. 34 Disconnect the battery negative terminal (refer to Disconnecting the battery In the Reference Section of this manual). 35 Undo the mounting bracket nuts and withdraw the unit from the inner wing (see Illustration). 36 Disconnect the ECU wiring connector, then remove the unit from the engine compartment.
6.15 Fuel rail securing bolts (arrowed) 27 Remove the resonator, air cleaner and inlet air duct as described in Section 2. 6.35 Undo the mounting bracket nuts and withdraw the ECU from the inner wing

4A*2 Fuel system -
single-point
petrol Injection models
Refitting 37 Refitting Is a reversal of removal making sure that the wiring connector is securely reconnected.
Inertia safety switch 36 Refer to Chapter 4A, Fuel injection system relays Removal 39 The fuel injection system twin relay Is located under a plastic cover on the engine compartment bulkhead. 40 The main purpose of the relay Is to supply current to the fuel pump, ignition coils, oxygen sensor, Injectors and EVAP solenoid. The relay is controlled by the ignition switch. A15 amp fuse, protecting ihe fuel pump, oxygen sensor and EVAP solenoid is located adjacent to the relay. 41 Remove the cover and pull the relay directfy from Its socket. Refitting 42 Refitting is a reversal of removal.
7 Fuel pump and fuel gauge sender unit - JK removal
and
refitting ^
Removal Note: Refer fo (he warning given in Section 1 before proceeding. 1 Disconnect the battery negative terminal (refer to Disconnecting the battery In the Reference Section of this manual). 2 Depreasurise the fuel system as described in Section 9. 3 Remove the rear soat as described In Chapter 11. Prise the fuel pump access cover out of the floor panel to gain access to the pump unit. On later models, undo the three retaining screws to release the cover. 4 Disconnect the wiring connector. 5 Bearing In mind the warning given In Section t, disconnect Ihe fuel supply and, where applicable, the return lines from tho pump unit by pressing the tabs. Plug the ends of the lines or cover them with adhesive tape. 6 Using a suitable tool, unscrew the large ring nut and carefully withdraw the fuel pump/fuel tank sender unit assembly from the fuel tank, along with its sealing rtng. 7 If necessary, the unit can be dismantled and the pump and sender unit separated. If this is (he case, carefully note the correct fitted positions of all components while dismantling the unit, and use these notes on reassembly to ensure that all items are correctly fitted.
Refitting 8 Refitting is a reversal of the removal procedure using a new sealing ring. Prior to refitting the access cover, reconnect the battery, then start the engine and check the fuel line unlon(s) (or signs of i

Fuel
tank -removal and refitting
Refer to Chapter 4A.
9 Fuel injection system -depressurisatton
Note: Refer to the warning given In Section 1 before proceeding.

A


Warning: The following procedure will merely relieve the pressure In the fuel system • remember that fuel will still be present In the system components and take precautions accord-ingly before disconnecting any of them. 1 The fuel system referred to in this Section is defined as the lank-mounted fuel pump, tha fuel filter, the fuel rail, the fuel injectors, and the metal pipes and flexible hoses of the fuel lines between these components. All these contain fuel which will be under pressure while the engine Is running and/or while the Ignition is switched on. The pressure will remain for some time after the Ignition has been switched off. and must be relieved before any of these components are disturbed for servicing work. 2 Disconnect the battery negative terminal (refer to Disconnecting the battery In the Reference Section of this manual). 3 Have a large rag ready to cover the union to be disconnected and, if possible, place a con-tainer beneath the relevant connection/union. 4 Slowly loosen the connection or union nut (as applicable) to avoid a sudden release of pressure, and ensure that the rag is wrapped around the connection to catch any fuef spray which may be expelled. Once the pressure is released, disconnect the fuel line, and Insert plugs to minimise fuel loss and prevent the entry of dirt Into the fuel system. Note that on later models, quick-release fuel couplings are used on many of the fuel line connections. To release these couplings, depress the two clips on the side of the coupling while keeping the fuel line pushed In. With the clips depressed, slowly withdraw the fuel line from the coupling allowing the fuel pressure to release, then withdraw the fuel line fully.
10 Inlet manifold-removal
and
refitting
Note: Refer fo the warning given in Section 1 before proceeding.
1242 cc (8-valve) engines
Removal 1 Remove ihe throttle body assembly as described in Section 5.
2 Remove the fuel rail and injectors at described in Section 5. 3 Drain the cooling system ss described n Chapter 1A. 4 Disconnect the wiring connector from ih* coolant temperature sensor (situated on it* left-hand side of the manifold). 5 Undo the bolt securing the accelerator cable mounting bracket to the manifold, am position it clear of the manifold. 6 Slacken the retaining clip and disconnect the coolant hose from the rear of the mandold 7 Disconnect the brake vacuum hose, 6 Undo the seven manifold retaining nuisw bolts, and remove the manifold from tta engine. Remove the gasket and discard tti new one should be used on refitting. Refitting
9 Refitting is a reverse of the removjf procedure, noting the following points: a) Ensure that the manifold and cylinder lim mating surfaces are dean and
dry.
and fill new manifold gasket. Refit the
manifold
and securely tighten Its retaining
nuts.
b) Ensure all relevant hoses are recorwscfed fo their original positions and are
sacurtfy
held (Where necessary; by the
retaining
clips. c) Refit the fuel rail and injectors, and
the
throttle body assembly with
reference to
Sect/on 5. d) On completion, refill the cooling
system
as described in Chapter 1A. 1242 cc (16-valve) engines
Removal 10 Disconnect the battery negative ternnncf (refer to Disconnecting the battery in ths Reference Section of this manual). 11 Remove the resonator, air cleaner and inlet air duct as described In Section 2. 12 Drain the cooling system as described r, Chapter 1A. 13 Free the accelerator inner cable from IN throttle cam. remove the outer cable spring dip. then pull the outer cable out from itt mounting bracket rubber grommet. 14 From the side of the throttle boOf, disconnect the wiring connectors from the throttle potentiometer and the Idle contrd stepper motor. Disconnect the coolant temperature sensor wiring connector located in the Inlet manilold below the throttie bodr, and disconnect the brake servo vacuum hose. 15 Disconnect Ihe wiring connectors for the fuel in|ector harness and the Intake a* temperature/pressure sensor, thtn disconnect the fuel pressure regulator vacuum hose and the EVAP purge valve
hose
(see illustration). 16 Undo Ihe two bolts securing the plastic Inlet manifold upper section to the lower section. Release the spark plug HT lead from the location groove in the manifold upper section, then lift Ihe upper section, complete with throttle body, off the engine. Recover
the
O-rings from the manifold pons.

Fuel system - diesel models 4C*3
Torque wrench settings Nm Ibfft Fuel injection pump roar bracket .. . 29 21 Fuel Injection pump .... 25 18 Fuel Injectors 41 Fuel pipe union nuts .... 30 22 Inlet manifold .... 24 18 Lower oil tiller mounting and injection pump mounting nut ..... .... 71 S2 Turbocnarger to exhaust manifold .... <10 30 Upper Dtl filter mounting end injection pump mounting nut 98 72
1 General information and precautions
General information The fuel system consists of a rear-mounted fust tank, a fuel filter with integral water separator, a fuel injection pump, in|eciors and associated components. A turbocharger is fitted to TDS, TD and TDSX models. Fuel Is drawn from the fuel tank to the fuel Injection pump by a vane-type transfer pump Incorporated in the fuel injection pump. Before reaching tho pump, the fuel passes through a fuel filter, where foreign matter and water aro removed. Excess fuel lubricates the moving components of the pump, and Is then returned to the tank. On turbo models with the Bosch fuel Injection systom, an eiectncally operated heater is incorporated In the fuel filter housing. The fuel injection pump is driven at half-crankshaft speed by the timing belt. The nigh pressure required to inject tho fuel into the compressed air in the swirl chambers Is achlovod by a cam plate acting on a single piston on the Bosch pumo, or by two opposed pistons forced together by rollers running in a cam ring on the Lucas (CAV) pump. Tlie fuel passes through acentral rotor with a single outlet drilling which aligns With ports leading to the Injector pipes. Fuel metering is controlled by a centrifugal governor, which reacts to accelerator pedal
position end engine speed. The governor is linked lo a metering valve, which increases or decreases the amount of fuel delivered at each pumping stroke. On turbocharged models, a separate device also Increases luel delivery with increasing boost pressure. Basic injection timing is determined when the pump is fitted. When the engine is running, it Is varied automatically to suit the prevailing engine speed by a mechanism which turns the cam plate or ring, Tho four fuel injectors proouco a homogeneous spray of fuel Into the swirl chambers located In the cylinder head. The Injectors are calibrated to open end close at critical pressures lo provide efficient and even combustion. Each injector needle is lubricated by fuel, which accumulates In the spring chamber and is channelled to the injection pump return hose by loak-off pipes Bosch or Lucas fuel system components mBy be fitted, depending on the model. Components from the latter manufacturer are marked either CAV. Roto-dlesel or Con-diesel. depending on their date and place of manufacture. With the exception of the fuel filter assembly, replacement components must be of tho same make as those originally fitted. Cold starting is assisted by preheater or glow plugs fitted to each swirl chamber. On the Bosch injection pump, an automatic cold Injection advance device operated through a thermal switch, advances the injection timing by Increasing the fuel pressure. The device operates at coolant temperatures below 55° C,
A stop solenoid cuts the fuel supply to V* Injection pump rotor when the ignition i switched off (see illustration) Provided that the specified maintenance* earned out. the fuel injection equipment #» give long and trouble-free service, ft* j injection pump itself may well outlast tlx ' engine, The main potential cause of damage j to the injection pump and injectors is dirt e water in the fuel. 1 Servicing of the injection pump and injectwi: j, is very limited for tho home mechanic, antf dismantling or adjustment other than thtf described In this Chapter must be entrusted to ' a Rat dealer or fuel Injection specialist.
Precautions

A


Warning: It Is necessary to takt I certain precautions when woriong , on the fuel system component^ particularly the fuel Injectors. Befon carrying out any operations on tho fuel system, refer to the precautions given* Safety first! at the beginning of Mis manual, and to any additional wamlrq notes at the start of the relevant
Sections.

2 Air cleaner and inlet system ^ • removal and refitting S
Removal 1 Remove the air cleaner element u described In Chapter 1B (see illustration).
1.9 Stop solenoid on the injection pump 2.1 Releasing the air cleaner cover clips

Fuel system - diesel models 4C*3
2.7a Unscrew the bolt... 2.7b ... and remove the Inlet air duct assembly
2.9b ... remove the air cleaner body...
Non-turbo models 2 Disconnect the intermediate air duct from
the
sir cleaner cover and the resonance box. 3 Disconnect the inlet duct from the resonance box and unbolt It from the front of
the
engine compartment. 4 Unscrew tho mounting nuts and remove the resonance box. Note the location of the special spacers. 6 If necessary unbolt and remove the support Brackets for the resonance box. Turbo models 6 Disconnect the intermediate air duct from the air cleaner cover and front Inlet air duct assembly. 7 Unbolt and remove the inlet oir duct tssembty (see illustrations). 6 Disconnect the air ducts from between the
air
cleaner and turbocharger. and between the turbocharger and Inlet manifold.
2.9c ... and spacers
9 Unscrew the mounting nuts and remove the air cleaner body. Note the location of the special spacers (see illustrations).
Refitting 10 Refitting is a reversal of the removal procedure.
3 Accelerator cable -removal, refitting and adjustment
Removal 1 Remove the air inlet ducting as described in Section 2. 2 Working In Ihe engine compartment, remove the cylindrical spring clip, and release the Inner cable from the lever (see illustration).
2.9a Unscrew the mounting nuts...
3 Pull the outer cable from the grommet in the fuel injection pump bracket (see illustration). 4 Release the cable from the remaining clips and brackets in the engine compartment, noting Its routing. 5 Working under the Instrument panel inside the vehicle, unhook the cable from the fork at the top of the pedal arm. 6 Release the bulkhead grommet and withdraw the accelerator cable from inside the engine compartment.
Refitting 7 Refitting Is a reversal of removal, but ensure that the cable is routed as noted before removal, and on completion, adjust the cable as follows.
Adjustment 8 Remove the spring clip from the accel-erator outer cable (see illustration). Ensuring that the control lever Is against its stop, gently pull the cable out of Its grommet until all Iree play is removed from the inner cable. 9 With the cable held In this position, refit the spring clip to the last exposed outer cable groove in front of the rubber grommet and washer. When the clip is refitted and the outer cable is released, there should be only a small amount of free play in the inner cable. 10 Have an assistant depress the accelerator pedal, and check that the control lever opens lulty and returns smoothly to its stop.
4C
32 Remove the spring clip and release the inner cable 3.3 Removing the outer cable 3.8 Removing the spring clip Irom the accelerator outer cable

Fuel system - diesel models 4C*3
8.5 Dial gauge (1), mounting bracket (2) and setting rod (3) In position on the injection pump (Lucas)
so that Its tip Is In contact with the bracket linkage (see Illustration). Position the dial gauge so that its plunger is at the mid-point of its travel and zero the gauge. 6 Rotate the crankshaft slowly in the correct direction of rotation (clockwise) until the crankshaft is positioned at TDC on No 1 piston with ell the sprocket timing marks aligned. 7 Check the reading on the dial gauge which should correspond to the value marked on the pump (there is a tolerance of * 0.04 mm). The timing value may be marked on a plastic disc attached to the front of the pump, or alternatively on a tag attached to Ihe pump control lever (see illustrations). 8 If adjustment is necessary, slacken the front pump mounting nuts/bolt and the raar mounting bolt, then slowly rotate tne pump body until the point is found where the specified reading is obtained on the dial gauge (access to the lower front bolt is gained through the hole in the injection pump sprocket). When the pump Is correctly positioned, tighten both its front mounting nuta/bolt and the rear bolt to their specified torque settings. 9 Withdraw the timing probe slightly, so that it
positioned clear of the pump rotor dowel. Rotato the crankshaft ihrough one and three quarter rotations in the normal direction of rotation. 10 Slide the timing probe back Into position ensuring that it Is correctly seated against the guide sealing washer surface, not (he upper Hp, then zero the dial gauge. 11 Rotate the crankshaft slowly in the correct direction ol rotation to the TDC position and recheck the timing measurement 12 If adjustment Is necessary, slacken the pump mounting nuts and bolt and repeat the operations in paragraphs 6 to 11. 13 When the pump timing is correctly set. remove the dial gauge and mounting bracket and withdraw the timing probe. 14 Refit the screw and sealing washer to the guide and tighten it securely.
8.7a Pump timing value (x) marked on plastic diso (Lucas)
15 If the procedure is being carried out as part of the pump refilling sequence, proceed as described in Section 5. 16 If the procedure is being carried out with the pump fitted to the engine, refit the injector pipes tightening their union nuts to the specified torque setting. Reconnect the battery and refit the air inlet ducting. 17 Start the engine, and check for any leakage at the fuel unions. To enable the engine to start it may be necessary to loosen tho injector union nuts while turning the engine on the starter motor in order to purge trapped air. 18 Check and If necessary adjust the Idle speed as described In Chapter 1B.
9 Fuel Injectors -testing, removal and refitting Sk ^

A


Warning: Exercise extreme caution when working on the fuel injectors. Never expose the hands or any part of the body to Injector spray, as the high working pressure can cause the fuel to pen ot rate the skin, with possibly fatal results. You are strongly advised to have any work which involves testing the injectors under pressure carried out by a dealer or fuel Injection specie list.
Testing 1 Injectors do deteriorate with prolonged uso, and it is reasonable to expect them to need reconditioning or renewal after 60 000 miles
8.7b Pump timing values marked on label (1) and tag (2) (Lucas)
(100 000 km) or so. Accurate testing, overhaul and calibration of the Injectors must be left to a specialist. A defective injector which Is causing knocking or smoking can be located without dismantling as follows. 2 Run the engine at a fast idle. Slacken each Injector union In turn, placing rag around the union to catch spilt fuel, and being careful not to exposa the skin to any spray. When tho union on the defective Injector is slackened, the knocking or smoking will stop.
Removal 3 Remove ihe air Inlet ducting from tho front part of the onglne. 4 Carefully clean around the Injectors and injector pipe union nuts. 5 Pull the leak-off pipes from the injectors (see illustration). 6 Unscrow the union nuts securing Ihe injector pipes to the fuel Injection pump. Counterhold the unions on the pump when unscrewing the nuts. Cover open unions lo keep dirt out, using small plastic bags, or fingers cut from discarded (but clean!) rubber gloves. 7 Unscrew the union nuts and disconnect the pipes from the ln|ectors, If necessary, the Injector pipes may be completely removed-Note carefully the locations of the pipe clamps, for use when refitting. Cover tho onds ot (he injectors, to prevent dirt ingress. 8 Unscrew the injectors using a deep socket or box spanner, and remove Ihem from the cylinder head (see Illustration). 9 Recover the tire seal washers from the cy-linder head and discard them (see illustration).
9.5 Disconnecting the Injector leak-off pipes 9.8 Removing an injector

4D«1
Chapter 4 Part D:
Exhaust and emission control systems
Contents
Catalytic converter - general Information and precautions 7 Crankcase emission system • general information 3 Evaporative loss emission control system • information and component renewal 2
Degrees of difficulty
Exhaust manifold - removal and refitting 5 Exhaust system - general information and component renewal .... 6 General information 1 Lambda oxygen sensor - removal and refitting 4

Easy, suitable
tor novice with fittie ^
1 experience
Fairly easy, suitable for beginner with ^ some experience ^
Fairiy dfficult, lb suitable for competent ^ DIY mechanic ^
Difficult, suitable for experienced DIY ^ mechanic
Very difficult, ^ suitable far expert DIY or professional
Specifications
Torque wrench settings Exhaust down pipe to manifold Exhaust manifold Exhaust system mounting Exhaust to catalytic converter: M8 M10x1.25
Nm Ibfft 24 18 24 18 27 20
24 18 40 30 53 39
1 General information
Emission control systems All petrol engine models use unleaded petrol and are controlled by engine management systems that are 'tuned' to give the best compromise between driveability. luel consumption and exhaust emission production. In addition, a number of systems are fitted that help to minimise other harmful emissions: a crankcase emission-control system (petrol models only) that reduces the release of pollutants from the crankcase, an evaporative loss emission control system (petrol models only) to reduce the release of hydrocarbons from the fuel tank, a catalytic converter (petrol and diesel models) to reduce exhaust gas pollutants, and an Exhaust Gas Recirculation (EGR) system (turbo diesel models only) to reduce exhaust emissions. Crankcase emission control To reduce the emission of unburned hydrocarbons from the crankcase Into the atmosphere, the engine is sealed and the blow-by gases and oil vapour are drawn from inside the crankcase, through a flame trap.
into the inlet tract to be burned by the engine during normal combustion. Under conditions of high manifold depression (idling, deceleration) the gases will by sucked positively out of the crankcase. Under conditions of low manifold depression (acceleration, full-throttle running) ihe gases are forced out of the crankcase by the (relatively) higher crankcase pressure: if the engine is worn, the raised crankcase pressure (due to increased blow-by) will cause some of the flow to return under all manifold conditions. Exhaust emission control -petrol models To minimise the amount of pollutants which escape Into the atmosphere, a catalytic converter is fitted In the exhaust system. The fuel system is of the closed-loop type, in which a Lambda (or oxygen) sensor In the exhaust system provides the engine management system ECU with constant feedback, enabling the ECU to adjust the air/fuel mixture to optimise combustion. The Lambda sensor has a heating element built-in that Is controlled by the ECU through the Lambda sensor relay to quickly bring the sensor's tip to Its optimum operating temperature. The sensor's tip Is sensitive to oxygen and relays a voltage signal to the ECU
that varies according on the amount of oxygen In the exhaust gas. If the inlet air/fuel mixture is too rich, the exhaust gases are low in oxygen so the sensor sends a low-voltage signal, the voltage rising as the mixture weakens and the amount of oxygen rises In the exhaust gases. Peak conversion efficiency of all major pollutants occurs if the inlet air/fuel mixture Is maintained at the chemlcally-con*ect ratio for the complete combustion of petrol of 14.7 parts (by weight) of air to
1
part of fuel (the stoichiometric ratio). The sensor output voltage alters in a large step at this point, the ECU using the signal change as a reference point and correcting the Inlet air/fuel mixture accordingly by altering the fuel Injector pulse width. Exhaust emission control -diesel models An oxidation catalyst is fitted in the exhaust system of all diesel engine models. This has the effect of removing a large proportion of the gaseous hydrocarbons, carbon monoxide and particulates present in the exhaust gas. An Exhaust Gas Recirculation (EGR) system Is fitted to all turbo diesel engine models. This reduces the level of nitrogen oxides produced during combustion by Introducing a proportion of the exhaust gas back into the inlet manifold, under certain engine operating

4D*2 Exhaust and emission control systems
2.2 Charcoal canister location behind tho right-hand headlight
conditions, via a plunger valve, The system is controlled electronically by means of an emissions system control unit. Evaporative emission control • petrol models To minimise the escape of unburned hydrocarbons Into the atmosphere, an evaporallve loss emission control system is fitted to petrol models, The fuel tank filler cap Is sealed and a charcoal canister is mounted underneath the right-hand headlamp to collect the petrol vapours released from the fuel contained In the fuel tank. It stores them until they can be drawn from the canister (under the control of the fuel Injection/ignition system ECU) via the purge valve into the Inlet tract, where they are then burned by the engine during normal combustion. To ensure thai the engine runs correctly when it is cold and/or idling and to protect the catalytic converter from the effects of an over-rich mixture, the purge control valve is not opened by the ECU until the engine has warmed up, and the engine is under load; the valve solenoid is then modulated on and off to allow the stored vapour to pass into the inlet tract.
Exhaust systems The exhaust system comprises the exhaust manifold, an exhaust downpipe, • catalytic convorter, an intermediate pipe with silencer, and a tailpipe with silencer, On turbo diesel models the turbocharger is fitted between ihe exhaust manifold and the downpipe.
5.5a On 16-valve engines, undo the bolts and remove the manifold heat shield...
2 Evaporative loss emission ^ control system - information and component renewal ^
Information 1 The evaporative loss omission control system consists of the control solenoid (or purge valve), the activated charcoal filter canister and a series of connecting vacuum hoses. 2 The control solenoid and charcoal canister are both mounted on the right-hand side of the engine compartment behind the headlight (see illustration).
Component renewal
Control solenoid 3 With the bonnet open, disconnect the hoses from the control solenoid on the top of the charcoal canister. 4 Disconnect the wiring and remove the solenoid. 5 Refitting is a reversal of removal. Charcoal canister 6 Remove Ihe control solenoid as desenbed previously. 7 Disconnect Ihe fuel tonk hose from the canister 8 Detach the mounting and remove the canister. 9 Refitting Is a reversal of removal. Multifunction valve 10 The multifunction valve >s mounted on top of the luel tank. Removal and refitting is similar to that described for the tank sender gauge/pump (refer to Chapter 4A or 4B).
3 Crankcase emission system - general information
The crankcase emission control system consists of a hose from the camshaft cover to the air cloanor with a branch to Ihe throttle body. The main hose Incorporates a flame trap and the Inlet to the throttle body incorporates a calibrated hole.
5.5b ... then remove the bracket
The system requires no attention other than to check at regular intervals that tho hoses are free of blockages and undamaged.
4 Lambda oxygen sensor -removal and refitting &
Note: 7?5e Lambda oxygen sensor is doiicata and will not work if it is dropped or knocked, it its power supply is disrupted, or if any cleaning materials are used on it.
Removal 1 The sensor Is threaded Into the exhaust front downpipe. Access if best gained Irom underneath the vehicle. Apply the handbrake then )ack up the front of the vehicle and support on axle stands (see Jacking and vehicle support). 2 Disconnect the sensor wiring connector located on the front of the engine. 3 Working beneath the vehicle, unscrew the sensor, taking care to avoid damaging the sensor probe as it Is removed- Note: As a flying lead remains connected to the sensor after it has been disconnected, if the correct spanner is not available, a slotted socket
will
be required to remove the sensor.
Refitting A Apply a little anti-selze grease to (he sensor threads • avoid contaminating the probe tip. 5 Refit the sensor to the downpipe. tightening it to the correct torque. Reconnect the wiring. 6 Lower the vohicle to the ground.
5 Exhaust manifold - % removal and refitting jk
Petrol models
Removal 1 On 1242 cc (16-valve) engines, remove tho air cleaner and inlet system components as described in Chapter 48. 2 Firmly apply the handbrake, then jock up the front of the car and support It securely on axle stands (see Jacking and vehicle support). 3 Disconnect the oxygen sensor wiring or alternatively romovo Ihe sensor completely. 4 Unscrew the nuts and disconnect the exhaust downpipo from Ihe exhaust manifold flange. Recover the gasket. 5 On 1242 cc (16-valve) engines, undo the bolts and remove the manifold heat shield, then remove the bracket at the timing belt end of the manifold (seo Illustrations). 6 Unscrew the mounting nuts, remove the washers, and recover any additional brackets fitted over the studs, noting their locations. Withdraw the manifold from the studs on the cylinder head. 7 Recover the gaskets from Ihe studs.

4D*3 Exhaust and emission control systems
Refitting 8 Refitting is a reversal of the removal pro-cedure but fit new gaskets. Tighten the nuts lo the specified torque.
Diesel models Note: On diesel models the inlet and exhaust
manifolds
are located on the rear of the engine
end
share the same securing nuts and gasket. Removal 8 Remove the inlet manifold as described In Part
C
of this Chapter. 10 Firmly apply the handbrake, then jack up lite front of tho car and support it securely on axle stands (see Jacking and vehicle support). 11 Straighten the tab washers (where fitted), then unscrew and remove the exhaust downpipe retaining nuts. Detach the downpipe from the manifold/turbocharger. Suitably support the downpipe. 12 Undo the manifold-to-cylinder head securing nuts and withdraw the manifold (see Illustration). 13 Separate the turbocharger from the manifold with reference to Chapter 4C. 14 Remove the gasket and clean the mating
(aces
of the manifold, cylinder head and down-pipe flange (see illustration). The gasket must
be
renewed when refitting the manifold, Refitting
15 Refitting is a reversal of the removal procedure but fit a new gasket. Tighten the retaining nuts to the specified torque and where necessary lock them by bending over
the
tocktabs.
6 Exhaust system - % general information and ^ component renewal
Genera/ Information 1 A three section exhaust system is fitted consisting of a twin-branch front downpipe, a catalytic converter, and a tailpipe with two silencers. The downpipe-to-manifold and downpipe-to-catalytic converter joints are both of flange and gasket type, whereas the remaining joint Is of the sleeve type secured
witn
a clamp ring (see illustration). 2 The system is suspended throughout its entire length by rubber mountings.
Removal 3 Each exhaust section can be removed individually or, alternatively, the complete system can be removed as a unit. Where separation of the rear sleeve Joint is necessary, it may be more practical to remove
the
entire system rather than try and separate
the Joint
In position. 4 To remove the system or part of the system, first jack up the front of the vehicle and support on axle stands (see Jacking and nhlcle support), Alternatively position the
vehicle
over an inspection pit or on car ramps.
5.12 Removing the exhaust manifold (diesel engine) Downpipe 5 Support the catalytic converter using an axle stand or blocks of wood. Where applicable on petrol models, refer to Section 4 and remove the oxygen sensor from the exhaust downpipe. 6 Unscrew and remove the bolts securing the downpipe to tha catalytic converter, then separate the joint and recover the gasket. 7 Bend back the locktabs (where fitted) then unscrew the nuts securing the downpipe to the exhaust manifold/turbocharger. and lower the downpipe, Recover the gasket. Catalytic converter
8 Support the tailpipe section of the exhaust using an axle stand or blocks of wood. 9 Unscrew and remove the bolts securing the downpipe to the catalytic converter, then separate the joint and recover the gasket. 10 Unscrew the clamp bolt and separate the converter from the tailpipe section. 11 Release the mounting rubber and remove the converter from under the vehicle. Tailpipe and silencers 12 Support the catalytic converter using an axle stand or blocks of wood. 13 Unscrew the clamp bolt and separate the catalytic converter from the tailpipe section. 14 Release the tailpipe section from its mounting rubbers and remove from under the vehicle. Complete system 15 Disconnect the downpipe from the ex-haust manifold as described in paragraph 7.
6.1 Exhaust clamp ring securing the tailpipe to the front exhaust system
5.14 Removing the oxhaust manifold gasket (diesel engine) 16 With the aid of an assistant, free the system from all its mounting rubbers and manoeuvre it out from underneath the vehicle. Heatshield 17 The heatshield is secured to the underbody by bolts and Is easily removed once the exhaust system has been removed.
Refitting 18 Each section is refitted by a reverse of the removal sequence, noting the following points. a) Ensure that all traces of corrosion have been removed from the flanges and renew ail necessary gaskets. b) Inspect the rubber mountings for signs of damage or deterioru tion and renew
as
necessary. c) Before refitting the tailpipe joint, smear some exhaust system jointing paste to the joint mating surfaces to ensure an air-tight seal. Tighten the clamp bolt. d) Prior to fully tightening the rear joint damp, ensure that all rubber mountings are correctly /ocafed and that there is adequate clearance between the exhaust system and vehicle underbody.
7 Catalytic converter -general information and precautions
The catalytic converter is a reliable and simple device which needs no maintenance In itself, but there are some facts of which an owner should be aware if the converter is to function properly for its full service life.
Petrol models a) DO NOT use leaded petrot In a car equipped with a catalytic converter - Ihe lead will coat the precious metals, redudng their converting efficiency
and
will eventually destroy the converter. b) Always keep the ignition and fuel systems well-maintained in accordance with the manufacturer's schedule. c) If the engine develops a misfire, do not drive the car at all (or at least as little
as
possible) until the fault is cured.