Air fuel ratio protection uses the Target AFR table, and the currently reported AFR read by a wideband sensor to protect the engine should it go out of limits (ie very lean while under boost etc).


Be sure to set-up your Lambda System, as well as your Target AFR table correctly, and of course your fuel map/tune should give the intended target AFR under normal use. See the Lambda section for more details on this part.


In the below example we allow a max deviation from the Target AFR table of 0.5AFR, We only check for this when the Minimum MAP, TPS and RPM settings are met. This stops us monitoring for example on overrun or part throttle.


If the AFR goes outside the target by more 0.5 (either rich or lean) for more than 100mS, then we will limit the engine to ZERO RPM.