What do you set the throttle % for hi and lo on a b18b, any help on how to tune the bastard?......

 

i want to know to

 

i installed an safc on my 94 LS this morning. i have an intake, header, and 2 1/2 exhaust, so i figured i'd set all rpms (1000-8000) to +5%. i left the hi and low throttle % at 10% low and 50% hi, which is default.

i'm getting more power in my car after installing it, that's for sure. The tires break loose easier in 1st and 2nd, there's more pull in the mid rpms (2nd and 3rd) than before. i'm guessing i gained around 5-8 peak hp, i think even more in the mid range. i hope i'm not too lean!! i'm gonna check my plugs tomorrow.

EDIT BOY WAS I WRONG ABOUT THAT THROTTLE % ISSUE




[Modified by LS-G, 10:20 PM 6/14/2002]

 

That's not it at all:

Throttle % allows you to interpolate between the narrow and wide throttle curves. If you have LO set to 25% and HI set to 75% then if your throttle is pressed 25% or less, it will work off of whatever you have set at that particular RPM on the narrow map. So lets say 18% throttle @ 3000 RPM and your narrow map says to take out -5% @ 3000 RPM. If you were pressing the throttle 75% or more at the same RPM it would entirely work off of the wide throttle map. So lets say your wide throttle map is set to add 5% @ 3000 RPM that's exactly what it will do.

Now, if your throttle is in between 25% and 75% it will interpolate the values so if you're at 3000 RPM at 50% throttle it will average the two values (so +5% and -5% would average to 0% correction). If you're at 60% throttle it will use more of the HI map than the LO map so the correction would end up to be like +2%.

It's real simple once you get it, it's just hard to put into words. If your % throttle is below the LO setting it will use only the narrow map. If you press over the HI setting you're using only the wide throttle map. If you're in between you're interpolating between those values.


[Modified by 5 Liter Eater, 9:32 AM 6/14/2002]

 

Is this the same way as the S-AFC hack works or is it totally different.

 

I had my lo at 50% and high at 70%

 

The S/V-AFC hack is different. It works by setting the narrow and wide maps to ~-40% with ~450cc injectors. The TH % is up to you.

I have my LO/HI throttle points set at 10%/90% because I know the wide map is tuned for WOT on the dyno and the narrow is tuned for cruising at very low throttle so I want the VAFC to interpolate everything in between for me.


[Modified by 5 Liter Eater, 10:15 AM 6/14/2002]

 

Have u had your car on a dyno or have had any problems with the hack. I want to run the hack, but am just worried about the car like at part throttle and still in closed loop mode. Looks like it would be leanning out.

 

At WOT the car runs similar to when I had 310's and a Cartech but the real benefit of the AFC hack is at part throttle. No more hesitation just before boost and using my "calibrating a modified fuel system" method I am able to tune out most LTFT so it acts just like stock injectors off boost.

 

My hi/lo is 1%/99%

but my maps are identical so it doesn't really matter.... I still need to get to the dyno but still need a aem rail and injectors (370s)

 

How much boost are you and 5 Liter Eater pushing? No sign of detonation?

 

Thank you for clearing that up. I didn't fully understand what the tech was telling me, but it sounded a lot like how you explained it.

I understand it a lot more now that it's been explained to me twice.



[Modified by LS-G, 10:06 PM 6/14/2002]

 

5 Liter eater, are there any advantages to having the thr% interpolate the fuel curve compared to directly setting them? it seems like you would have more control by setting the %s individually, but i don't know.
??

 

What kinda fuel injectors are you guys using? Because your adding fuel, must be really really rich...