The roller-type cam follower comprises a sheet- metal moulding acting as a lever and a cam roll with a roller bearing. The cam follower is clipped onto the support ele- ment and seated on the valve.
The hydraulic support element has the same function as the hydraulic bucket tappet. It serves as a hydraulic valve lifter and support for the roller-type cam follower.
The lubrication system
Lubricant flows between the hydraulic support element and the roller-type cam follower as well as between the cams and the cam roll along an oil duct integrated in the support element. Oil is injected into the cam roll through a drilling in the roller-type cam follower.
Oil
Cam roll
Lubricant duct
196_009
Function
The support element serves as a pivot for the rol- ler-type cam follower. The cam contacts the cam roll and presses the lever down. The lever in turn activates the valve.
A high valve lift is achieved with a relatively small cam due to the fact that the leverage bet- ween the cam roll and support element is smaller than between the valve and support element.
It is not possible to inspect the hydraulic support elements.
196_011
Engine Mechanics
The hydraulic support element
serves as a support for the roller-type cam follower and hydraulic valve lifter.
Design
The support element is connected to the oil circuit. It comprises the following elements:
- a piston, - a cylinder and - a piston spring.
A small ball, in combination with a pressure spring integrated in the lower oil chamber, makes up the one-way valve.
Hydraulic valve lifter
If valve backlash occurs, the piston spring forces the piston out of the cylinder until the cam roll makes contact with the cam. When the piston is pressed out of the cylinder, the oil pressure in the lower oil chamber drops. The one-way-valve opens and surplus oil flows into the oil chamber. The one-way-valve closes when the pressure between the lower and upper oil chambers has been equalised.
Valve lift
When the cam contacts the cam roll, the pres- sure inside the lower oil chamber rises because the oil here cannot be compressed. The piston cannot be forced any further into the cylinder. Thus, the support element acts as a rigid support for the roller-type cam follower. The inlet or exhaust valve opens.
10
Piston with drilling
Cylinder
Upper oil chamber
Lower oil chamber
196_014
Oil inlet
Piston spring
One-way valve
Valve clearance
196_016
196_017
Connecting drive
Tension pulley Connecting drive
Deflection pulley
196_021
Belt-driven crankshaft gear
The toothed belt drive
The toothed belt drive is divided into a main drive and a connecting drive on account of the small overall width of the of the cylinder head.
Main drive
Main drive
The coolant pump and the intake camshaft are driven by the crankshaft by means of a toothed belt integrated in the main drive. An automatic tension pulley and two deflection pulleys reduce toothed belt fluctuation.
Deflection pulley
Belt pulley Coolant pump
Tension pulley Main drive
The connecting drive
is located outside the cylinder head.
The exhaust camshaft is driven by the intake camshaft by means of a second toothed belt integrated in the connecting drive.
Again, an automatic tension pulley reduces too- thed belt fluctuation.
You can find exact instructions for adjustment the camshaft timing in the Workshop Manual.
196_024
11
Engine Mechanics
The crankcase
used in the 1.4-ltr. 16V 55kW engine is made of die cast aluminium.
The liners are made of gray cast iron. They are press-fitted in the crankcase and machinable.
Land with press-fitted cast iron liners
Coolant duct
Section of the aluminium crankcase of the 1.4-ltr. engine
For corrosion reasons, only coolant additive G12 is approved for use.
196_086
12
The crankshaft
is manufactured from gray cast iron and has only four balancing weights. Despite this weight saving, the crankshaft has the same running cha- racteristics as a crankshaft with eight balancing weights.
The 1.6-ltr. 16V 88kW engine has a crankshaft with eight balancing weights.
Bearing seats
Balancing weight
Balancing weight
Bearing cover
196_087
Crankshaft
Balancing weight
You must not remove or loosen the crankshaft in the 1.4-ltr. engine.
Even when you loosen the bearing cover screws, the inner structure of the aluminium bearing seat relaxes, resulting in deformation of the crankshaft. If you undo the bearing cover screws, you must replace the crankcase complete with the crankshaft.
13
Engine Mechanics
The sealing flange
The crankcase is sealed with a sealing flange on the clutch side. The sender wheel for the engine speed sender G28 is integrated in the sealing flange.
In future, sealing flanges of two manufacturers will be used for this engine generation. The designs of these sealing flanges (e.g. engine speed sender housing) differ to such an extent that they cannot be replaced with another make of sealing flange.
Engine speed sender G28
Sealing flange with spring-ring gasket
In this case, the joint between the sealing flange and the sender wheel is sealed with a spring-ring gasket. The sender wheel is also sealed off from the crankshaft by an elastomer gasket. The sen- der wheel is precisely pressed onto the cranks- haft.
Crankshaft
Elastomer gasket
Sender wheel
Gasket
Sealing takes place at the sender wheel.
14
196_100
196_099
Sealing flange Sender wheel
Section of crankshaft
sender wheel
Sealing flange
Sealing flange with PTFE sealing ring
PTFE stands for polytetrafluorethylene. It is better known as Teflon - a special type of heat- and wear-resistant plastic.
The PTFE sealing ring sealing is located directly between the sealing flange and crankshaft. No additional elastomer gasket is needed. With this type of sealing flange, too, the sender wheel is pressed onto the crankshaft in a precise posi- tion.
Crankshaft
PTFE sealing ring
Sealing takes place on the crankshaft.
Engine speed sender G28
PTFE gasket
196_097
Sealing flange
Sender wheel
Section of crankshaft
Sender wheel
Sealing flange
196_098
For detailed instructions for installing the various sealing flanges, please refer to the Workshop Manual.
15
Engine Mechanics
The duocentric oil pump
is designed as a crankshaft oil pump. This means that the inner race is seated directly on the crankpin at the front end of the cranks- haft. The special shape of the crankshaft at the crank- pin has made it possible to reduce the outer dia- meter of the oil pump to only 62mm.
The term (cid:210)duocentric(cid:211) describes the geometric shape of the gearing of the inner and outer races.
In addition to a reduced level of friction and a weight saving of approximately 1kg, engine noise emission has also been improved by driving the crankshaft directly.
The oil pump housing rounds off the engine block at the front end.
Crankpin with polygonal profile
196_081
Housing
Outer race
196_020
Inner race
16
Cover plate
Function
The inner race is seated on the crankpin and drives the outer race. The space between the gears on the intake side is enlarged when the inner and outer races rotate, due to their diffe- rent axes of rotation.
Oil is is drawn in through a snorkel-type intake and conveyed to the delivery side.
The space between the gears becomes smaller on the delivery side. The oil is forced into the oil circuit. A pressure limiting valve prevents the maximum permissible oil pressure being exceeded, e.g. at high engine speeds.
Oil is drawn in
196_004
Oil is forced into the oil circuit
Pressure limiting valve
196_007
17
Engine Mechanics
The con rods
are machined using two different methods depending on their source: 1. Cutting, 2. Cracking.
Cutting
Cracking
In the cutting process, the con rod is initially rough-machined and then cut into a piston rod and piston rod cover. These two parts are bolted together for finish-machining purposes.
In the cracking process, the con rod is initially pre-machined as a complete part. At the end of this process, the con rod is separated by a tool into a piston rod and piston rod cover with great force.
The advantage:
The resulting fracture face is unique. This means that only the same two parts match up with one another. The con rod costs less to produce.
- Good positive connection.
196_072
196_082
196_073
196_074
As a rule, con rods must be replaced as a set. Don(cid:213)t forget to mark which con rod belongs to which cylinder.
18
Exhaust system
The main goals for the development of the exhaust system were to save space and weight and, above all, to meet tougher exhaust emission standards.
The exhaust manifold comprises four single pipes which converge on a flange. This results in a weight saving of approximately 4.5kg in comparison with conventional exhaust systems. In addition, the exhaust manifold, cata- lytic converter and lambda probe reach opera- ting temperature more quickly and exhaust gas treatment is initiated sooner.
In the case of 1.4-ltr. engine with the engine code AKQ, a micro catalytic converter with a metal substrate is welded into the headpipe of the exhaust system. This metal substrate is coated with a catalyst. The lambda probe is situated upstream of the micro catalytic converter.
196_077
Micro catalytic converter
Heat shield
Lambda probe
196_076
19
Test your knowledge
1. The valve gear of the 1.4-ltr. 16V 55kW engine
a) is housed in the cylinder head and camshaft housing,
b) has camshafts which run in three bearings and whose axial clearance is limited by the bearing
cover and camshaft housing,
c) has a cylinder head containing the valve gear complete with a cylinder head cover.
2. For valve activation via the roller-type cam follower
a) the valves and levers are securely interconnected,
b) any valve backlash which arises is adjusted automatically,
c) there is less friction and moving mass than in the case of bucket tappets,
d) a large cam must provide sufficient valve lift.
3. The crankshaft
a) must be removed and relubricated for inspection,
b) must not be loosened and can only be replaced complete with the crankcase.
4. Please annotate the following drawing.
d)
a)
b)
c)
20
e)
f)
196_018
Engine Management
Magneti Marelli 4AV Engine Control Unit
The Magneti Marelli 4AV engine management system is used for the new engine generation. It is housed in the plenum chamber.
The engine control unit has the following stan- dard functions:
In contrast to engine control unit version 1AV, version 4AV has:
- Cylinder-sequential injection
with quick start function, Intelligent idling speed control, Intelligent lambda control, Intelligent tank ventilation, Intelligent exhaust gas recirculation, Intelligent knock control, - Self-diagnostic capability.
- a static high-voltage distribution, - a Hall sender at the intake camshaft and
- an engine speed sender at the
crankshaft instead of the previous system of engine speed recognition via the distributor.
196_101
Rngine control unit, 80-pin connector
196_092
21
Control unit
for 4AV
J448
Engine Management
System overview
Intake manifold pressure sender G71
with
intake air temperature sender G42
Engine speed sender G28
Hall sender G40
Knock sensor I G61
Lambda probe G39
Coolant temperature sender G62
Throttle valve control unit J338 with
Idling speed switch F60
Throttle valve potentiometer G69
Throttle valve positioner potentiometer G88
Speedometer sender G22
Control unit with display unit integrated in
the dash panel insert J285
Additional input signals Air conditioning system compressor signal Air conditioning system pressure signal
22
Ignition transformer N152
Injectors N30, N31, N32, N33
Fuel pump relay J17
Fuel pump G6
Activated charcoal filter system solenoid
valve I N80
Throttle valve control unit J338 with
throttle valve positioner V60
Exhaust gas recirculation valve N18
Additional output signals Engine speed signal Air conditioning system compressor signal
Immobiliser control unit J362, Diagnosis plug connection
196_002
23
Engine Management
Static high voltage distribution
The ignition transformer for the static high- voltage distribution is located at the end of the camshaft housing.
The advantages of the static high-voltage distri- bution are:
- no mechanical wear (maintenance free),
- no rotating parts, - higher ignition energy compared to the
low susceptibility to faults,
rotating ignition distribution fewer wires carrying high voltage.
196_069
The engine control unit calculates the spark timing between two ignition cycles. Engine speed and engine load are the key data which it requires for this purpose. Other influencing factors include the coolant temperature and the knock control. The engine control unit can adapt the spark timing to any operating state of the engine in this way. This increases engine efficiency, reduces fuel consumption and reduces exhaust emissions.
Electric circuit
The output stage and ignition coils are grouped together in the ignition transformer. Cylinder pairs 1 & 4 and 2 & 3 have a common ignition coil, which means that the cylinders of each pair are fired simultaneously. The one cylinder is shortly before the power stroke and the other is at the exhaust stroke.
J448
Cylinder: 1 4
196_096
Effects of failure
Without the ignition transformer or ignition coil, it is not possible to supply the spark plugs with energy.
24
The engine speed sender G28
is installed in the sealing flange and secured by a screw.
Signal utilisation
The engine speed sender scans a 60-2 sender wheel with 58 teeth and a gap the size of two teeth serving as a reference mark. The sender wheel is positioned on the crankshaft.
The engine control unit uses the signal which the engine speed sender supplies to determine the engine speed and the exact position of the crank-shaft. This data defines the injection and spark timing.
Engine speed sender G28
60-2 sender wheel
Reference mark
Sealing flange
196_008
Electric circuit
Effects of signal failure
J448
If the engine speed sender fails, the engine con- trol unit enters emergency mode. The control unit then calculates the engine speed and and deter- mines the position of the camshaft from the infor- mation which Hall sender G40 supplies. To protect the engine, maximum engine speed is reduced. It is still possible to restart the engine.
G28
196_094
Make sure that the engine speed sender is used by two different manufacturers.
25
Engine Management
Hall sender G40
is located on the flywheel side of the camshaft housing above the intake camshaft. Attached to the intake camshaft are three cast teeth which the Hall sender scans.
Signal utilisation
The signals which the Hall sender and engine speed sender supply are used for determining the ignition TDC of the first cylinder. This informa- tion is necessary for cylinder-selective knock con- trol and sequential injection.
Effects of signal failure
If the sender fails, the engine continues to run and can also be restarted. The engine control unit enters emergency mode. Fuel is then injected into the cylinders in parallel and no longer sequentially.
Bearing cover
26
Electric circuit
As with the throttle valve potentiometer G69, the Hall sender is supplied with power by the engine control unit.
J448
G69
G40
196_095
Hall sender G40
196_019
Intake camshaft with cast sender wheel
Camshaft housing
Hall sender G40
Rising edge
Solenoid field of the sensor
196_078
Signal from engine speed sender
196_079
Signal length corresponds to tooth length
General function
A Hall voltage is generated whenever a tooth passes the Hall sender. The duration of the Hall voltage pulse corresponds to the length of the tooth. This Hall voltage is transmitted to the engine control unit and evaluated here.
The signals can be displayed with the digital memory oscilloscope of the VAS 5051.
Cylinder 1 recognition function
If the engine control unit simultaneously receives a Hall voltage from the Hall sender and the refe- rence mark signal from the engine speed sender, this means the engine is in the compression stroke of the 1st cylinder. The engine control unit counts the teeth of the speed sender wheel after the reference mark signal and thus determines the crankshaft posi- tion.
For example: the 14th tooth after the reference mark corresponds to TDC of the 1st cylinder.
Quick start recognition function
The momentary position of the camshaft relative to the crankshaft can be ascertained quickly using only three teeth. This enables the first combustion cycle to be initiated sooner and the engine to start more quickly.
196_080
27
Functional Diagram
Components
A/+ Battery positive terminal
F60
Idling speed switch
30
15
J17
Fuel level indicator sender Coolant temperature sender Fuel pump Engine speed sender Lambda probe
G2
G6
G28
G39
G40 Hall sender
G42
G61
G62 Coolant temperature sender
Throttle valve potentiometer
G69
G71
Intake manifold pressure sender
Throttle valve positioner potentiometer
G88
Intake air temperature sender Knock sensor I
Fuel pump relay
J17
J285 Control unit with display unit
integrated in the dash panel insert Throttle valve control unit Immobiliser control unit Control unit for 4AV (injection system)
J338
J362
J448
Exhaust gas recirculation valve
Injection valve, cylinder 1
Injection valve, cylinder 2
Injection valve, cylinder 3
Injection valve, cylinder 4
N18
N30
N31
N32
N33
N80 Solenoid valve 1 for
activated charcoal system
N152 Ignition transformer
Spark plug connector Spark plugs Fuse
V60
Throttle valve positioner
Signals
Air conditioning system pressure signal
Air conditioning system compressor signal
Diagnosis connection
Fuel consumption indicator of J448
for multifunction display
Speed signal from J448
28
A/+
N18
N30 N31 N32 N33
G6
N80
G39
G71
Input signal Output signal Positive Earth
S
N152
J448
G61
J285
J362
V60
F60
G69
G88
G42
J338
G40
G62
G2
G28
30
15
196_001
Depending on vehicle type, the immobiliser control unit is located in the dash panel insert (e.g. Golf (cid:212)98) or in the dash panel (e.g. Polo).
29
Self-diagnosis
The following functions can be read out with fault reader V.A.G. 1551, system tester V.A.G. 1552 or the vehicle diagnosis, testing and information system VAS 5051:
01 Interrogate control unit version 02Interrogate fault memory 03 Actuator diagnosis 04 Start basic adjustment 05 Erase fault memory 06 End of output 08 Read measured value block
(cid:222)
196_103
196_104
196_102
Function 02 Interrogate fault memory
Fault in the colour-coded sensors and actuators saved to fault memory.
G42
G71
G28
G40
G61
G39
G62
J338
F60
G69
G88
G22
N152
N30, N31, N32, N33
J17
N80
J338
V60
N18
30
196_083
Function 03 Actuator diagnosis
During actuator diagnosis, the following components are activated one after the other:
Throttle valve positioner V60,
- Solenoid valve 1 for activated charcoal system N80,
- Exhaust gas recirculation valve N18,
- Engine speed signal,
- Fuel pump relay J17
- Engine/air conditioning compressor (electrical connection)
Function 04 Basic adjustment
The basic adjustment procedure must be performed if the engine control unit, the throttle valve control unit or the engine are to be replaced together with the throttle valve control unit.
Function 08 Read measured value block
The measured value block provides assistance with troubleshooting and inspecting the actuators and sensors. The signals of the coloured-coded components are output in function 08.
G42
G28
G39
G62
J338
F60
G69
G88
G22
N80
Air cond. compressor input Battery voltage
196_084
31
Service
Special-purpose tools
For repair work on the 1.4-ltr. 16V 55kW engine, you also require the following special-purpose tools:
Designation
Tool
Usage
T10016
Camshaft locking tool
For locking the camshaft gears when removing the camshaft housing
T10017
Assembly device
Replacing the crankshaft sealing flange on the flysheel side
T10022 - Sleeve
Replacing the crankshaft sealing ring on the belt pulley side
T10022/1 - Thrust piece T10022/2 - Spindle
Replacing the crankshaft sealing ring on the belt pulley side
32
Test your Knowledge
1. What functions differentiate the Magneti Marelli 4AV engine control unit from version 1AV?
a) Cylinder-sequential injection
b) Static high-voltage distribution
c) Camshaft sensor at the intake camshaft
d) Engine speed sender at the crankshaft
e) Diagnostic capability
2. What are the functions of Hall sender G40?
a) It is for engine speed recognition only.
b) Recognition of the 1st cylinder.
c) It facilitates the quick start function.
3. Which of the following statements is true?
a) The speed sender G28 is inserted into the crankcase from the exterior.
b) The speed sender G28 is installed in the sealing flange and
secured by a screw.
c) The speed sender G28 is mounted in the crankcase and can only be accessed by removing
the sump.
4. What cylinders are supplied with ignition voltage by what coil?
J448
a) b) c) d)
a)
b)
c)
d)
Cylinder
Cylinder
Cylinder
Cylinder
33
Notes
34
4.a) cylinder 1, b) cylinder 4, c) cylinder 2, d) cylinder 3
3.b)
2.b), c)
1.b), c), d)
Page 33
d) hydr. support element, e) Intake camshaft, f) roller-type cam follower
4. a)Exhaust camshaft, b) camshaftn housing, c) cylinder head lower section,
3. b)
2. b), c)
1. a), b)
Page 20
Solutions:
35
Service.
196
For internal use only ' VOLKSWAGEN AG, Wolfsburg
All rights reserved. Subject to technical modifications.
740.2810.13.00 Technical status: 03/98
This paper is produced from
non-chlorine-bleached paper.