Understanding Lambda in Automotive Logs

Understanding Lambda

Lambda is actual air/fuel ratio divided by the stoichiometric air/fuel ratio for the fuel being used.

For gasoline using a 14.7 stoichiometric reference:

lambda = 12.0 / 14.7
lambda = 0.816

Lambda below one is richer than stoichiometric, while lambda above one is leaner than stoichiometric.

When a compatible commanded lambda channel is present, target error can be measured. When it is absent, PullScan should explain the limitation and continue with valid actual-signal behavior rather than fabricating a target.