EMTRON ELC USER MANUAL
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© EMTRON AUSTRALIA PTY LTD MARCH 2018
14
6.0 Exhaust Back Pressure (EMAP) Compensation
Wideband Lambda sensors primarily count oxygen atom numbers through measuring the
oxygen ion current within the sensors pump cell. The exhaust gas pressure affects this
oxygen ion current. The more pressure means more atoms per unit volume and a
higher
pump current at the same Lambda i.e. this will cause the sensor to read farther from
stoichiometric.
A rich reading will appear richer than it really is.
A lean reading will appear leaner than it really is.
This predominantly becomes an issue in Turbocharged applications. This is the main reason
you should position the sensor after the turbo where exhaust back-pressure is lowest.
Excessive Exhaust Back Pressure (EMAP) can also damage the sensor. The following rule
should be observed:
Exhaust Back Pressure
< 2.5 Bar
When measuring Exhaust Back Pressure, an Absolute Pressure Sensor MUST be used. (i.e.
do not
use a Gauge Pressure Sensor). The ECU MUST have the Exhaust Manifold Pressure
channel configured so data transmitted from ECU to ELC is valid.
The EMAP setting can be enabled by going to the the Config View -> Communications Tab ->
Emtron CAN Device -> Emtron Lambda to CAN (ELC/ELCM) Setup and selecting the
“
Enable
EMAP
”
setting to ON (Figure 6.0). Once enabled to ECU will transmit the EMAP value over
the CAN Bus and the ELC will received this value so the correction can be applied.
Figure 6.0. Emtune ELC setup menu - EMAP Enable
NOTE:
Once changed, the setting is automatically stored by the ELC and therefore used on
the next power cycle.
