air fuel ratio during lean cruise

[The1]

obviously holden dont then, most factory tunes are 16 - 20:1

[vlad01]

thats weird. I seen and had the opposite effect. when i had some engine running too rich the exhaust would glow.
The excess fuel would burn in the exhaust causing massive head and exhaust temp increase. Timing would also play a role in this for sure.

Many other engine developers I know have show this in misconfigured tunes.

engine destroying afr are typically running 14.7 at load or WOT, running richer at WOT is for engine protection and power. Running leaner than that is only for light loads. thats why its called lean cruise.

[antus]

Yep, its all a balance I guess, theres more than one reason why things get hot. Stoich is the best balance for emissions and smooth running and engine life, and about 12.5:1 for power and engine temp under power or a bit richer again under boost (11.5ish?). A bit lean for fuel savings is ok at light loads but not a huge gain and not necessary. Then things heat up and make less power to the point of stumble and stall when you go too far in any direction.