Stang9946

Even with the mods I have, my computer would throw a code if I was running too lean or too rich right? It's a safety feature yes?

oxfordgt

I wouldnt worry about it. If that is a canned tune you have then you are running a bit rich and will be fine. You don't have any mods that will effect your A/F ratio.

Stang9946

Well I wanted to lean it the full 6% with my Excal 2 and wanted to make sure that would be ok. Brent from Brenspeed said the tune he gave me was set at about 13.0

oxfordgt

Don't touch the A/F without a wideband. If it is actually set at 13:1 then leave it. That is the max power your gonna get from a/f adjustments. Try maxing out the spark.

cliffyk

+1,000 do NOT mess with fuel settings without a wideband sensor. Also, you will find that when tuners say "it's set at about 13.0:1" they are referring to the AFR in open loop, at or near WOT, under heavy load (as in wide open on a dynamometer)--that's the way they think.[/align][/align]At partial throttle and light to medium loads (I.e. closed loop operation) it will roam from14.3:1 to 15.2:1 so as to average 14.7:1. Maybe even a bit higher (as high as 16.0:1) at steady light loads (like 60 on level ground), as that's where the best fuel economy is. The tuners don't mess with closed loopsettings much 'cause there's not really anything to be gained there...[/align]

oxfordgt

Yeah I got my light load set at 15.7:1 and WOT at 12.5:1 and of course idle is 14.7:1 until I drop in the new cams. Saves alot on gas mileage but gives me the power when I need it.

Romer

But wouldn't 12.5 be way too lean for a stock motor? 13 sounds extreme

oxfordgt

LOL no. 12.5 is the safest for best power 13.2:1 is lean but best torque production 11.5:1 is rich but best torque on the rich side. Of course those numbers all move richer by a full point when your FI. 12.5 is very safe for a stock engine, by the way the heads and cams are the only thing left on my car that are stock.

cliffyk

[/align][/align]You don't seem to hava a clear grasp on A/F ratios -- < 14.7:1 = rich; > 14.7:1 = lean...[/align][/align]14.7:1 is the "stoichiometric" ratio for air and gasoline--I.e the ideal ratio for full efficiency conversion of aur and fuel to energy;[/align][/align]However the real world often in out of synch with the ideal world and when accelerating, gasoline engines produce higher output with richer (more gas than air) mixtures of 13.0:1 to 11.5:1 (forced induction engines like the richer of these);[/align][/align]Another real world oddity is that best fuel economy can be attainedwith mixes as high as 16:1 and even 17:1 (if other operational conditions permit)--most modern autos are tuned to operate in this range under light loads;[/align][/align]I.e. there is no one AFR that optimally meets all operating conditions...[/align][/align]

cmher18

And when we talk wideband were not talking about the $25 light show from autometer. I paid $315 for mine. Innovative with band with the XB16 gauge or something like that