SSANGYONG RODIUS 2004.09 Manual page 223

05-3
1913-01
1913-01
ENGINE EXHAUST SYSTEM
1.BEFORE DIAGNOSIS
The base of making diagnosis on the EGR related system is the inspection on the connections
of the vacuum hoses in related system as the first priority. When abnormal condition occurs
with the EGR system, the basic approach is, as described in prior sentence, making detail
inspections of vacuum circuits of each system before connecting the scan tool or vacuum
tester. It is necessary to manually check on the connections if there are any slacks or loose
circuits even
if the visual inspection shows vacuum hose as being connected. If there are not any problems
then the next inspection area is the connections of the system connectors. Most problems with
the occurrence of system malfunction are from conditions of vacuum line and connector
connections and the causes from the malfunction of mechanical mechanism is actually very
few.
For example, when there are no problems with basic components, let's assume that there
is a vehicle having vacuum leak from connection slack in the vacuum line between EGR
vacuum modulator and EGR valve. This vehicle, due to the driving condition or, according to
the circumstances, smog or other conditions, could create customer's complaint and by
connecting the scanning device could display as the malfunction of the EGR valve's
potentiometer.
As previously explained, this car has a separate controller to control the HUBER EGR and, in
accordance with various input element, the controller controls EGR valve by regulating the
force of vacuum being applied to the EGR valve through PWM control. At this time, the
controller has to receive feedback whether the EGR valve operates correctly according to the
value sent to the EGR modulator and this role is performed by the EGR potentiometer located
at top section of the
EGR valve.
In other word, the controller sent correct output value to the EGR vacuum modulator but, due to
the leakage of vacuum, signal of required value can not be received from the EGR
potentiometer causing to display as malfunction of related parts.
As a reference, the EGR valve of diesel vehicle (DI Engine) controlling from the engine ECU to
EGR system has different shape than the HUBER EGR valve because the EGR valve's
operation signal in the DI engine is performed by the HFM sensor instead of the EGR
potentiometer.
This principle is that when the EGR valve opens up to flow exhaust gas into the intake unit the
amount of fresh air, comparatively, will be reduced. The DI engine ECU receives feedback
signal of change in amount of air being passed through the HFM sensor according to the
opening amount of the EGR valve.
ENGINE EXHAUST SYSTEM
RODIUS 2004.09