air condition AUDI A4 1997 B5 / 1.G APB Engine Electronic Engine Power Control Checking Workshop Manual

24-139


Electronic Engine Power
Control (EPC), checking

Function of Engine Power Control (EPC)

With the electronic throttle, the throttle valve is
not operated by a cable connected to the
accelerator pedal. There is no mechanical link
between the accelerator pedal and the throttle
valve.
The throttle valve is actuated by a servomotor
(throttle valve positioner) in the throttle valve
control module over the full range of engine
speeds and load conditions.
The throttle valve positioner actuates the throttle
valve according to the commands it receives
from the Engine Control Module (ECM).
The position of the accelerator pedal is
communicated to the Engine Control Module
(ECM) by two accelerator position sensors
(variable resistors, both installed in a single
housing) which are connected to the accelerator
pedal.
The accelerator pedal position (as determined by
the driver) is one of the main input values for the
Engine Control Module (ECM).
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Under certain engine load conditions there is
also a significant reduction in harmful emissions
and noticeably improved fuel consumption.
The Engine Control Module (ECM) can provide
the optimum combination of throttle valve
opening and charge pressure in order to create
the required torque.
The electronic throttle is not simply a
combination of two or three components, but
rather a complete system comprising all the
elements that together determine the position of
the throttle valve and also control and monitor it.
For example, the Accelerator Pedal Position
Sensor, Throttle Valve Control Module, EPC
warning lamp, Engine Control Module (ECM)
etc.
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Test conditions for adaptation of throttle
valve control module

No malfunctions stored in DTC memory
Page 01
-15
, check DTC memory

Engine not running, ignition switched on
Accelerator pedal not depressed
Coolant temperature between 5 C and
100 C (Display group 004, display field 3)

Intake air temperature less than 100 C

Voltage supply to engine control module
greater than 11Volt, Checking Page 28
-32

- Connect vehicle diagnostic, testing and
information system VAS 5051 or VAG1551 scan
tool and select engine electronics control
module by entering address word "01" Page
01
-9 . When doing this the ignition must be
switched on.
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24-150
When the -Q- button is pressed the throttle valve
positioner will be switched mechanically.
In this condition the throttle valve is pulled into an
"emergency running" or default position by a
mechanical spring in the throttle valve control
module. The values supplied by the two angle
sensors for this emergency running position are
stored in the Engine Control Module (ECM).
The throttle valve is then opened by a
predetermined amount. As soon as it reaches
this position the current supply to the throttle
valve positioner is again disconnected. The
spring should then close the throttle valve
mechanically to the previously learned default
position within a specified period of time (spring
test).
The throttle valve positioner then closes the
throttle valve and the values supplied by the
angle sensors in the throttle valve control module
are stored in the Engine Control Module (ECM).
If the ECM disconnects the current supply to the
throttle valve positioner while the vehicle is being
driven, the result will be an increase in idling
speed with fluctuating engine RPM (hunting) and
very slow throttle response.
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Kick-Down function, adaptation

On vehicles with automatic/inifinitely variable
transmission, when the accelerator position
sensor or the Engine Control Module (ECM) was
replaced, the Kick-Down function from ECM must
be adapted.

Test conditions

No malfunctions stored in DTC memory
Page 01
-15
, check DTC memory

Engine not running, ignition switched on

- Connect vehicle diagnostic, testing and
information system VAS 5051 or VAG1551 scan
tool and select engine electronics control
module by entering address word "01" Page 01
-9 .

When doing this the ignition must be switched
on.
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Display fields

1 2 3 4
Display Group 063: Kick-down function adaptation
Display xx % xx %

---
Indicated accelerator
position
sensor 1 accelerator
position
sensor 2
Adaptation condition
Work
range 0...100 % 0...100 %


Kick Down Activate
ADP. runs
ADP. OK
ADP. ERROR
Specified
value 12...97 % 4...49 %
Kick Down
ADP. OK
Note


IF "ADP. ERROR" is displayed: Check DTC memory Page
01
-15
.
Note:

The Abbreviation "ADP." stands for adaptation.
The "ERROR" display could appear, if the accelerator pedal was not immediately depressed after you have been
prompted or the accelerator pedal was released during the adaptation although the adaptation was not completely carried
out. In both cases the "Basic Setting" mode must be abandoned and the adaptation must be started again Page 24
-
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