[Formulajones]

Every engine will want something different.

I've been all over the place with cruise AFR looking for a sweet spot and that's what it's going to take, some experimentation.

I can tell you on my Chevelle it doesn't like being any leaner than 15:1 at cruise, in fact I'd say it's borderline happy there, and if I tried leaner the loss of power was noticeable and drivability suffered. However I've tried 15:1 on extended cruises and it doesn't pick up any more MPG. Because of that I've settled on low to mid 14's for cruise AFR on that particular car and the MPG's are the same.

One thing worth mentioning that I've done is run an extra Innovative wide band along side the 02 for the Holley. Don't know of anyone else that has mentioned trying this. I've noticed the Innovative consistently reads about a 1/2 point leaner than the holley 02 does at all points. Keep in mind I've used that Innovative wideband for tuning for many years on the street and at the track long before the car went EFI so I trust what it says. Actually the same deal on the GTO too with an Innovative wide band along side the Holley 02 and it reports almost exactly the same way, with the Holley about a 1/2 point leaner. Makes me curious what alga rhythm Holley uses on that 02 or what might be different about it.

Anyway, with that said, when I was experimenting with lean cruise on the Chevelle, it was the Innovative that was reading around 15:1 where the engine was borderline happy, while the Holley was reporting mid 15's for AFR. I eventually worked on the cruise areas in the fuel table to keep my AFR's around 14.3-14.5 on the Innovative which tickles the higher 14's on the Holley 02.

This still gets me the same MPG on the highway and the engine is happier. Keep in mind stoich for 10% ethanol fuels is 14:1 and not 14.7:1 so there's that to consider.

Trial and error till you find a happy spot.