AEM 30-71XX Infinity Stand-Alone Programmable Engine Mangement System Full Manual User Manual

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EFI Components

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Characteristic curve of a Nernst Cell O2 Sensor

The rich region output of narrow band O2 sensors is temperature dependent, which renders it
useless if an accuracy better than 1.5:1 AFR is desired. This is immediately obvious given the
fact that a single output voltage actually represents wildly different air fuel ratios depending on the
unregulated and unmeasured sensor temperature. These sensors were designed for operating
closed loop around stoichiometry (14.64:1 for gasoline), and for performance tuning they are
useless.

The AEM Infinity includes dual internal UEGO controllers. Only a Bosch LSU4.2 UEGO Sensor
may be used. This system is accurate and repeatable to 0.1 of an air/fuel ratio point. With this,
there is no abrupt oscillation as found in many competitor systems, which typically utilize a narrow
band oxygen sensor detecting only stoichiometry. sensor. This type of UEGO sensor is
commonly referred to as “laboratory grade” and works on a different principle than the narrow
band oxygen sensor found in most vehicles. Its unique design makes precision AFR
measurements possible over the entire operating range.