forced lean cruise

[MMGT1]

In the GTO your NB can handle the change to 14.2 or are you doing that open loop with a wide band? Did you not find that the GTO went rich using 14.2? Is there a strong fuel odour when you went to 14.2? Sorry to jump the thread on you here, but you are the first person I have had a chance to talk to in any depth about this. I would love to change my stoich to 14.2 if it is the right thing to do. Because of my compression I cannot use anything less than 93 in mine. So in Canada, its Sunoco 94 with 10% ethanol or nothing! Tried to tune it for less, could not stop KR no matter how much timing was pulled!

[StarCaller]

the change went perfect in closed loop. the car doesn't run rich at all, just right.
no gas smell, no soot in the tailpipe.
so running a little richer with 14.2:1 that should also help your knocking.

[MMGT1]

This is nuts to me... I am so fixated on having that 14.7:1 for so long it's a little hard to swallow. Well, Ill give it a whirl and see how it goes. This is making a hell of a lot more sense to me though because where I should make best power at 13:1 I am finding that my car is liking 12.5-12.7 WOT for best power. Maybe there has been something right under my nose for some time and I didn't even realize it, if they are even related.

[Iam Broke]

FWIW, after following this thread I tried a lambda of .965 (~14.2:1AFR)in my Turbo LNF at cruise for the last week instead of 1.0 or 14.7 to 1. In my region we are "up to 10%" ethanol also and the LNF has a wideband o2 sensor. I believe the current blend here is 5.5% but I'm catless so a bit richer than stoich on the DISI engine is no biggie.

Much less tip in knock retard and the fuel trims became more stable. Mileage is the same on my 85 mile loop or a pinch better. I have also always fought KR on it since I began tuning & the stock tune has 3-4* KR on 93 octane. It has improved for me on my tune as well.

[oldskool]

To the OP: you've done what I've long considered. My concern was that without the appropriate IAT and BARO correction tables, we cannot get a lean cruise tune to be perfrect in all seasons. A retune would probably be needed 2-3 times a year to keep it productive.

How stable is your AFR while cruising? More or less than using the NB in closed loop?