SSANGYONG KYRON 2007.04 Manual page 248

05-3
1913-01
1913-01
EXHAUST SYSTEM
1. INSPECTION 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 D20DT
KYRON 2007.04