Equation for tuning fuel maps. Please help before I try to tune.
 

Sorry for the new thread about the formula but I was doing some math and something doesn't work out for me correctly and I figured people could throw their 2 cents in to give me a hand.

Shoot me if I'm wrong but if you use the formula of: % to change=[(known/calculated)/known]*100 then it works sometimes. Example: [(10/11.5)/10]*100=8.6% then you want to pull 8.6% of your fuel. True, this was already discussed in a previous topic. My problem is like this if you are at 10 and you want to hit 14.7 then according to the formula you only pull 6.8% of your fuel which wont even get you to the previously mentioned 11.5. Am I doing something wrong here or is the forumla flawed?

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

8.6% equals 1:1 AFR change, so if you're at 10.5:1 AFR and you pull 8.6%, you would then be at 11.5:1

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

I see, so in theory if i want to get from 10.5 to 14.7 I should pull about 35%, IN THEORY-I'm not going to pull that much fuel at once because of how much it could truely affect, but that is how it works, right?

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

if you have a map in part throttle that runs 10.5 AFR's you should seriously consider a starting with a better basemap.

what part of your rpm range are you trying to lean out that much?

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

That seems really way too rich for a scaled basemap.

I would lean out 5 or 10% at a time in problem areas until you get closer to your target and then start using that formula. 35% is a pretty big jump.

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

No... the forumula is perfect, very simple math.

If you're at 10.5, and you want to be at 14.7.. Do this:

10.5 / 14.7 = 0.71428571428571428571428571428571

(0.71428571428571428571428571428571 - 1) = -0.28571428571428571428571428571429

-0.28571428571428571428571428571429 * 100 = -28.571428571428571428571428571429


...then you take, -29% ...very simple.

I use that formula in an autotune routine in my datalogger... I get almost perfectly flat AFRs in 3-4 pulls on the dyno... ..so, do whatever you feel like you need to do.

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

I see, I just had my formula wrong, thank you very much. Fook and 95redex 10.5 was just an example my map from xenocron is in the 11-13's range in vac. :)

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

ahh, you had me scurred for a minute there.

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

ok, say all that again for really stupid people :-\

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

[(where you are at/where you want to be) - 1] * 100

Example. your wideband reads 11.9 and you want to be at 14.7
11.9/14.7 = 0.809523809523

0.809523809523 - 1 = -0.190476190477

-0.190476190477 * 100 = -19.0476190477

So you highlight the area that you are at 11.9 and then pull 19% of your fuel from that area.

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

thanks DarkElvis for posting this question, i didn't even know about a formula

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

Hehehe. it's not really "a formula for tuning fuel"... it's just simple math to find the difference in two numbers. :)

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

yea, once you posted it i felt kinda stupid. It's just a simple percentage formula from like 6th grade math. O0

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

This formula makes tuning a LOT easier

Thanks

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

Awesome formula!

I suck at math so yes it helped, not so simple to me

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

yea, i was actually trying to figure this ---- out yesterday. I'm playing around with my map because its uber rich! my tail pipe is blacker than .....i duno, its just super ------- black.

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

Go back to math class buddy. 10.5 to 11.5 is 9.5% difference. The only time a 1.0 A/F change would happen with 8.6% change in fuel would be if you started at 11.63 A/F.

For fuel since the values are inverted to the A/F

(Current A/F - Target A/F) / (Current A/F) = % Change in fuel

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

why did you just requote yourself on a post from june...chug your mothers fat cock.

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

To make idiots like you wonder why. Get off my nuts already.

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

so you were incorrect with the equation Fook?

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

awesome thread! and like said guy .. this formula make tuning easier! ;)

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

yes, and madmax is just loving it too, he feels so much better about being the cock chugger he is because of it...we should all be so happy for him.

For the record, I don't tune with equations and keep a calculator open on my laptop all the time. I just feel it out and know about how much of an adjustment I need to make without even thinking about it. It's been effective and worked well for me on a good 30 cars here in portland now, and I only blow up my own, when I have them.

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

i think BETTER tuners tune ecus like you do but i guess to do through equations it's nor wrong neither.. not?

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

hey Fook, noone doubts in your tuning skills, but for me and many guys I believe this equation is like E=MC2 for phisicians, unless you are planning to come to Poland next day so I will be more than happy to give my car in your hands ;D and will forget any equations ;)

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

I tune the same way, but people asked for an equation so I gave it to them.

Re: Equation for tuning fuel maps. Please help before I try to tune.
 

Thats how the stock ECU compensates so instantaneously/makes up for all its flaws.