Lean Protection Parameters

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Lean protection is designed to protect the engine from an overly lean running condition, and also alert the driver to a potential problem.


Lean protection works by monitoring the front oxygen sensor, and performing a engine cut when the air/fuel ratio rises above a preset level for a designated time period. There are two lean protection parameters, so that two different air/fuel ratio to load relationships can be used.


Note that the front oxygen sensor must be of the wide band type, and working normally for lean protection to work.






Maximum Lambda is the maximum allowable air/fuel ratio for the lean protection, measured as an air/fuel ratio.


Engine Load is the minimum engine load for the lean protection to activate.


Trigger Time is the time period which the air/fuel ratio needs to leaner than the maximum lambda for the lean protection to activate.  This is to remove false protection triggering from throttle transients and engine load changes.


Once lean protection is triggered, the check engine light will illuminate and the engine will be cut.  The engine will be restored once the throttle is released or the engine rpm drops below 2000 rpm.


Note that when the launch control rev limiter is active, lean protection is disabled after launch.


Fail Safe Input




External fail safe inputs are supported,  giving a 2000 rpm limiter until the throttle is released.


Note that unlike lean protection no trigger timer is used as the external device should perform this function.