3
Setting up egrCAN (Hardware)
There are 2 steps to setting up the egrCAN hardware:
1.
Mounting O2
and pressure sensors on the engine
2.
Attach the modules to the bus
Mounting O2 and Pressure Sensors
Mounting “Air Module” O2 and Pressure Sensors
The air module’s O2 and pressure sensors should be mounted in a quiescent volume
containing the air that is to be drawn into the engine. Mounting could be as simple as
hanging the sensors by their wires in ambient air. Alternatively, the sensors could be
mounted on conditioned-air ducting leading to the intake of the engine.
ECM supplies both steel and aluminum mounting bosses for the air module’s O2 sensor and
pressure sensor (see Figure 2). However in some cases, user-designed sensor mounting
bosses may be more appropriate. It is important to minimize the velocity of air passing over
the O2 sensor as excessive cooling will lead to measurement errors. Keep in mind that the
O2 sensor gets very hot and will burn whatever it touches.
General rules and information for mounting are as follows:
•
O2 sensor thread is 18mm x 1.5mm
•
Pressure sensor thread is ¼” NPT
•
Pressure sensor must measure pressure within 2” (50mm) of the O2 sensor
•
Mount sensors so that no water will collect on either sensor
•
Mount sensors where air velocity is as low as possible
•
Apply pressure to pressure sensor through a ¼” or 6mm teflon hose if the proposed
pressure sensor mounting location is hot or vibrates
•
Locate pressure sensor where temperature is between -20 °C and 70 °C.
Mounting “Intake Module” O2 and Pressure Sensors
egrCAN determines the %EGR at the location of the intake module’s O2 and pressure
sensor. Although this at first might seem obvious, this is different from sampling-type (i.e.
pumping) %EGR measurement instruments that tend to average the %EGR measured from a
drawn volume surrounding the pump’s sample point. Consequently, egrCAN is both better
at measuring the distribution of EGR in an intake manifold and less intrusive. egrCAN
supports the use of multiple intake modules allowing the simultaneous determination of EGR
distribution in an intake manifold. Alternatively, multiple intake modules can be used to
determine %EGR for multi-stage EGR systems.
A 1” (25.4mm) tall aluminum mounting boss (P/N 12-04) is provided for the intake O2
sensor. The mounting boss places the tip of the O2 sensor flush with the inner wall of the
manifold and thus does not influence intake flow. The aluminum mounting boss can either
be welded (to aluminum manifolds) or epoxied (to plastic manifolds).