STFT + LTFT = 0 right??

[flipnoy213]

Im trying to tune my low throttle map in my S-AFC with my pocket logger. Unless i read wrong your suppose to make STFT and LTFT equal zero.

With that said, i see my self adding about +8% at 1000 rpm +15% 2000 rpm and +18% 3000 rpm and so on, just to get my STFT and LTFT to equal zero. WTF This really doesn't make any sense especially because i got 680 cc injectors. And when i start to drive the car with those settings it runs like shit.

Can anyone please tell me what am i doing wrong, pleeaseee!

Thanks

 

[GSTdude06]

Check for vac leaks.

 

[flipnoy213]

I just check and i found some leaks and was able to fix it. But it still does not seem right because my corrections are about -10% across. And i'm positive there is no more leaks.

I would assume it be close to -20% because i got 680s and High Press. Fuel Pump.

 

[GSTdude06]

How did you check the leaks?

 

[flipnoy213]

I used a 2.5 inch pipe end cap with attached a tire stem, attached it to my turbo inlet with a coupler, and fill it with a tire pump till 20 PSI

 

[GSTdude06]

Better if you use a compressor that pumps 20 in at once while a tire one just pumps it in gradually.

 

[flipnoy213]

yeah i used a 60 gallon air tank at work.

 

[GSTdude06]

hmm doesnt seem to make sense if all your leaks are fixed, try the soapy water test?

Set your short tirms first then after the 4000 mark put the 5000 6000 and 7000 the same as the 4000 along with your long tirm. Then go take a log and post it on here

 

[spoold]

680/450 - 1 = 51%

If youre using an afc youre just about pushing it limits of compensation, if you are indeed running 680's. That calculation above should be a baseline of what you would need to pull out to get the LTFT to equal 0.

I am on 560's and pull out about 22% +/- 5% and i have 0% LTFT all the time almost.

The LTFT will slowly "grow" towards the STFT, however, when youre LTFT's are 0, and does not really change even if the STFT change sporadically, you are golden.

 

[GVR4592]

680/450 - 1 = 51%

If youre using an afc youre just about pushing it limits of compensation, if you are indeed running 680's. That calculation above should be a baseline of what you would need to pull out to get the LTFT to equal 0.

I am on 560's and pull out about 22% +/- 5% and i have 0% LTFT all the time almost.

The LTFT will slowly "grow" towards the STFT, however, when youre LTFT's are 0, and does not really change even if the STFT change sporadically, you are golden.

You're formula is backwards, it would be 450/680 -1 = -33.8%

 

[GVR4592]

Im trying to tune my low throttle map in my S-AFC with my pocket logger. Unless i read wrong your suppose to make STFT and LTFT equal zero.

With that said, i see my self adding about +8% at 1000 rpm +15% 2000 rpm and +18% 3000 rpm and so on, just to get my STFT and LTFT to equal zero. WTF This really doesn't make any sense especially because i got 680 cc injectors. And when i start to drive the car with those settings it runs like shit.

Can anyone please tell me what am i doing wrong, pleeaseee!

Thanks

What are your fuel trims at right now? Does your O2 sensor cycle? Do you have a fuel pressure regulator for your 255hp?

 

[CanadianTSi]

To tune my low trims I just focus on my STFT and get it as close to 0 as possible, if your STFT is near 0 all the time your LTFT will come down to near 0 as well.

 

[Nanan]

I see you have a 255HP fuel pump, do you have a FPR? If you do not then you are going to have all kinds of problems with the stock fpr getting constantly overrun. You should be subtracting a boatload of fuel not adding it, you have something messed up like a boostleak in addition to the way to high fuel pressure.

 

[flipnoy213]

Monday I took my car to get it dyno tuned and before i went i did do a soapy water boost leak test again and everything was fine.
Heres the settings they did.
1000 2000 3000 3400 4000 4400 4600 5000 5400 6000 6400 7000
-16% -17% -30% -25% -31% -34% -36% -42% -41% -47% -42% -38% (Hi)
-21% -19% -20% -21% -30% -31% -20% -32% -26% -32% -27% -35% (Lo)

Checked my pocket logger and everything around +12 LTFT and STFT around +5
Car runs really good. But does not make sense

Oh and my O2 does cycle and i have no FPR

 

[mitsugst97]

well you need to get yourself an AFPR...! and then tune again.
I wouldn't expect to see your setting dip like that, normally it tends to be a smoother transistion. (if you graphed your tune it would look like you were tracking the stock market.. ) i would expect it to look more linear.
That could be from from your FPR getting over-run. maybe.

 

[flipnoy213]

okie i guess my next upgrade is a FPR. But im still trying to figure out how to tune my low throttle maps.