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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
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 (C 18 XE: 13 °CA,
X 20 XEV: 15 °CA) and the idle air adjuster to a fixed
position. There is no adjustment of the firing angle and idle air adjuster.
It is then possible to switch off the injectors of the individual cylinders.
After selecting this test, it is possible to select a
cylinder / injector using the arrow key "Up" and then,
with the arrow key "Down", to switch off / deactivate
the injector of each selected cylinder for 3.0 s.
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 air adjuster
position and before deactivating an injector, the engine runs at approx. 1200 rpm
(C 18 XE) or 1300 rpm (X 20 XEV). 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 oxygen 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 400 mV (see TECH 1 data list parameters "02 SENSOR" and"AIR / FUEL RATIO")
The actual oxygen sensor control, however, is switched off
after an injector is deactivated; i. e. parameter "02 INTEGRATOR" is at 128.
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 about 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.
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See note
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25, 26, 27, 28, 81,
82, 83, 84
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50, 49, 51, 48, 9
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