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03
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SELECT
CONTROL INJ. CONTROL
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Engine running at idle speed
Engine throttle valve CLOSED
(accelerator pedal in idle
position)
Vehicle stationary
Switch off all consumers
AC switch OFF
Vehicles with AT:
Selector lever in
"P" - "N" position
Press key F8 in the system
main menu, select the desired test using the arrow keys and confirm with YES.
Follow the instructions in the
TECH 1 display.
Note:
In this test mode,
TECH 1 sets the firing angle in the control unit to a fixed value
(20 °CA BTDC) and the idle speed adjuster to a fixed position. lt
is then possible to switch off the injectors for the various cylinders.
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25,
26, 27, 28, 81, 82, 83, 84
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14,
16, 17, 34, 35
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After the YES key is pressed in
the display on the right, TECH 1 uses the control unit to stabilize the
engine speed at approx. 1200 rpm. After stabilization in the above
range, the idle speed adjuster position is no longer altered and at this
point the actual test can begin. During the stabilization phase, the display
on the right can be seen
After the stabilization phase,
it is possible to select a cylinderlinjector using the arrow key
"UP" and then, with the arrow key "DOWN", to switch
off / deactivate the injector of each selected cylinder for 3 s.
If the engine is not properly
warm (coolant temperature lower than 100 °C / 212 °C) when
this test is started or carried out, the engine speed may oscillate
considerably between approx. 1300 and 2000 rpm in the upper engine speed
range (approx. 1900 rpm). To prevent this, always carry out this test at
high engine temperatures or use the TECH 1 arrow keys to lower the
engine speed during the test to avoid the upper engine speed range.
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INJECTOR
CUTOFF
: SELECT INJ.
¯
: OFF (3 SECS)
WAITING
FOR
RPM
TO
STABILIZE...
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03
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SELECT CONTROL INJ. CONTROL
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In addition, the YES and NO keys
can be used to display the various data list parameters. Key F9 is used to
store the data as in the snapshot mode.
After fixing the firing angle
and the idle speed adjuster position, i. e. after the actual start of the test
and before deactivating an injector, the engine runs at approx.
1200 rpm. The oxygen sensor control functions normally.
The test should only be started
if the radiator fan is not running (otherwise the engine speed may be approx.
200 rpm lower).
Once an injector is deactivated,
the engine speed sinks by approx. 200 rpm. If the radiator fan starts
running during the deactivation phase, this may lead to a further decrease of
the engine speed of approx. 200 rpm.
In this test phase, uncombusted
oyxgen from the deactivated cylinder gains access to the exhaust pipe. This
means that the engine runs lean and therefore that the oxygen sensor
constantly displays a voltage lower than 100 mV. The integrator, on the other
hand, operates at a correspondingly higher rate (greater than
128 steps), as the system attempts to enrichen the mixture.
The above described check should
be performed consecutively for each cylinder. They should all indicate the
same response, i. e. the engine speed should sink by the same amount for each
cylinder. The purpose of this check is not to test the function of the
injectors, but is intended as a check of the mechanism /
tightness / compression of each individual cylinder.
When this test is completed, the
engine may stall. This may especially be the case if the radiator fan is
running or other consumers are
switched on. The snapshot data recorded by TECH 1 is however
retained.
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25,
26, 27, 28, 29, 32, 81, 82, 83, 84, 85, 86
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15,
16, 17, 33, 34, 35,14
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