# JB2 lean during cruise?



## furui (Sep 30, 2007)

Hey. This question goes out to Burger Motorsports guys:

Does the JB2 go lean during cruising? A certain other product does this to save more fuel (at least with the default maps), so I am curious if the JB2 has a similar feature.

Thanks,

furui


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## Terry @ BMS (Apr 27, 2007)

furui said:


> Hey. This question goes out to Burger Motorsports guys:
> 
> Does the JB2 go lean during cruising? A certain other product does this to save more fuel (at least with the default maps), so I am curious if the JB2 has a similar feature.
> 
> ...


Hi Furui, the first JB2 prototype induced a 'lean cruise' but I eliminated it in the production version. I was concerned about long term reliability with the cats, and of course 'lean cruise' is a violation of federal smog law due to the increased emissions it produces.


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## furui (Sep 30, 2007)

Ah, cool. Thanks!


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## WilyB (Jan 10, 2007)

Terry @ BMS said:


> Hi Furui, the first JB2 prototype induced a 'lean cruise' but I eliminated it in the production version. I was concerned about long term reliability with the cats, and of course 'lean cruise' is a violation of federal smog law due to the increased emissions it produces.


Are you sure? I always had my Aston-Martin Vantage (Euro engine) tuned to extra lean to pass emissions here on the East Coast, then retuned back to normal.

May be it is different in California? :rofl:


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## WilyB (Jan 10, 2007)

Do I hear crickets?


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## Terry @ BMS (Apr 27, 2007)

WilyB said:


> Are you sure? I always had my Aston-Martin Vantage (Euro engine) tuned to extra lean to pass emissions here on the East Coast, then retuned back to normal.
> 
> May be it is different in California? :rofl:


I don't check this forum as often as I should. 

"Lean cruise" bumps up the NOx levels. You can still pass a smog check as they don't do testing at "cruise" speed (typically 60-80mph), but its bad for the environment. More importantly it's illegal. 

Tuning a car to pass smog is another story, I usually tell people to add in a couple of gallons of denatured alcohol, almost anything will pass running on that stuff.


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## DBville (Sep 2, 2007)

Manufactures design their products to work reliably under all sorts of conditions, and especially during cruise, they optimize it for fuel mileage, while meeting emissions. They are not concerned about power, as you are under very low load (60 mph takes what, 15 HP?).

I would not want to deviate from the manufacturers recommended _cruise_ settings because they have it set that way for a reason, Changing the cruise condition to try and eck out another mpg or two on a $45,000 car just doesn't make sense. :dunno:


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