AEM 30-71XX Infinity Stand-Alone Programmable Engine Mangement System Full Manual - Manual (Page 135)

Tuning Guide 129
© 2014 AEM Performance Electronics
Target Lambda
To control the engine's fuel delivery system, the Infinity can be programmed to run open loop and/
or closed loop O2 feedback. Closed loop uses feedback from the oxygen sensor to make
temporary, but immediate, corrections to the injection to maintain a target air fuel ratio (AFR) or
lambda. The type of the O2 sensor will determine how lambda target can be controlled. Due to
the nature of standard narrow band O2 sensors, the only accurate measurement that can be
maintained in closed loop is Lambda 1.0. However, wideband O2 sensors can be used in
almost every feedback condition.
Note that 14.64:1 is called the stoichiometric AFR for gasoline. It is the ratio where all available
fuel is burned completely. For most performance applications, it is not the ideal AFR to operate
the engine at all the time nor is it the AFR that creates the most power or even economy under all
conditions.
When the fuel system is open loop, the O2 sensor is ignored and the injector pulse width relies
on the VE Table and fuel compensators to adjust injection duration. Open loop is necessary
during engine starts, when the O2 sensor has cooled below its operating temperature. It may
also be necessary when coolant temperatures are low. In this state, the fuel vaporization is poor
and the engine will require a richer mixture to properly operate. When under heavy load, the
engine typically requires an air fuel ratio that is out of a narrow band oxygen sensor's standard
range and open loop will be necessary. When the accelairflow function is triggered during hard
accelerations, open loop may be necessary to help stabilize the Target Lambda. Also, when the
deceleration function cuts fuel completely, target lambda will not be necessary.
LambaTargetTable
Units: Engine Load vs Engine Speed vs Lambda
Description: This table sets the target lambda for various engine conditions.