beginner tune (SAFC2)

[dsmluver98]

ok guys i have done a lot of research lately and am trying to understand this whole tuning process on my own and i am unsure if its because there are other things going wrong with my car that i am having issues comprehending things or i just don't understand the concept period.. i would like some wise man to help out and anyone else dealing with things like this feel free to put some helpful advice please
alright i had my car tuned by JNZ tuning and then a buddy of mine was screwing around with my safc2 because he thought that i was running to rich all the time. which was kinda true my a/f gauge was reading 10 but who knows if it would go lower.. now my issue is that i cant full throttle without back fire and feels like fuel cut as well as just to scared because numbers jump from 10 -16 in any random order.. and also fuel used to get good mileage and now its crap just cruising..
my list of mods are (on a 1g)...
16g turbo, 3" exhaust, 560cc injectors, wally 190, front mount inter cooler, safc2, wide band, three inch intake pipe with the 1g maf,
I am seriously trying to jus get this car running good again and i dont want to ruin this motor its my 8th one since i cant find good mechanics and now i finally had a true mechanic and true tuner but im now all the way on the other side of the state
Any ideas?

 

[4g63Powered]

What is the S-AFC set at now? Your injectors (560cc) are ~24% larger, so start by pulling (going negative) 24%. That should get you a rough tune that you can then fine tune better.

Do you have a real Wideband O2? Not just a blinky narrowband gauge?

 

[dsmluver98]

1000 +7%
1800 +9%
2400 +7%
3000 +6%
3600 +4%
4200 +1%
4800-7000 +0%

and im running a aem wideband

that's a low setting... i don't know the high settings i didn't write them down i can if you want

 

[turboglenn]

To use an AFC you have to take bigger injectors and then fool the ECU with SAFC by using NEGATIVE VALUES ONLY, the minute some one put + positive values in the thing you started hitting fuel cut. The whole point with SAFC is to take larger injectors sothe car is pig rich and scale it back with SAFC to the lean area you want to be in.. (this is only on DSM's and the positves are there for cars that can get and make use of a positive reading)

Don't let said "buddy" touch anything to do with your car again, need to get a wideband and retune the thing now.. might as well put all the sliders at least down to -15% or so and not beat it untill you get a safe tune on it again

edit to match what you added.. if any high settings are positve you're definitely hitting fuel cut... some hack to the MAF may require a +setting in the low if i recal, but really i still don't think you need the positive side at all...

oh, ok and you have wideband i car..well it should jump all over any time you're not wide open, that's called closed loop cycling andis normal..when you go Wide open on pump gas you want the AEM to go to 11 or so and stay there.. so mess with the Hi settings under wide open to get those readinds and you'll be back to normal forthe most part

 

[dsmluver98]

thats what i thought but im negative like 20 % in the high i dont kno exact numbers but i kno most are 20s and if i go negative on the low end my a/f is reading blank at idle...

i was told if im wide open i should be at like 10.4-10.9 anywhere in between not 10 to 16 ha that's leaning at times right???

i am also wandering if trying to install a maft would be a good idea? or get a 2g maf?

 

[Chicken Patty]

Definitely you should not be having postivie #'s on the "HI" map. Like it was stated, I would pull 24% on the "HI" Map (-24%). Then at least there you should be fine to beat on the car. With positive settings your are actually making the ECU read more "airflow" than it really is reading so you definitely will fuel cut.

Do the -24% and do a pull in 3rd gear from about 2500 RPM's to redline, keep an eye on the wideband, shouldn't see anything higher than 11.5 on the AEM. From there, you can maybe take it to someone who knows to get it tuned.

 

[dsmluver98]

what about on my "LO" end?? and can someone dummy it down on the safc2 i mean i read up on it and i understand that its a piggyback to manipulate the ECU but all the features kinda contradict themselves don't they?? i mean from one of the articles i read that's what i got out of it

While i do my pull what should i do if it starts bucking or acting up?

 

[4g63Powered]

what about on my "LO" end?? and can someone dummy it down on the safc2 i mean i read up on it and i understand that its a piggyback to manipulate the ECU but all the features kinda contradict themselves don't they?? i mean from one of the articles i read that's what i got out of it

Think of it this way. Your new injectors are 124% the size of the stock ones; the computer in the car thinks it still has injectors.

So, for every one part of air, it is still telling the injectors to supply 1 part fuel.* This is sent via an electrical pulse to the injector which tells it to open.

Since the injectors are bigger and they still get the same pulse, the stock 1:1 ratio is now 1:1.24 which is causing you to run rich. The fact that you have positive trims dialed in means you are closer to 1:1.3

Now this is why you need to trick the computer. The S-AFC intercepts the MAF signal** and alters it by the amount you enter. So if you enter (-24%) as the value, the 1part incoming air is read as 0.76 parts by the computer.

This causes the computer to output an injector pulse for 0.76 parts.

So you have:

"0.76 parts of air": 0.76 parts fuel.

When in reality it is 1.0 parts air, and due to the injectors being larger than stock, you get the full 1 part fuel.

In essence, you are lying to the ECU so that it injects less fuel.



*Obviously, this is ignoring AFRs. We all know it isn't a 1:1 ratio but it works for the explanation.
**It's been a while; if it alters the outgoing injector pulse I apologize but I remember it changing the MAF signal.

While i do my pull what should i do if it starts bucking or acting up?

Watch your Wideband; if it goes rich (say, below 11.5 on full boost) pull more fuel out (go farther negative). It it starts to creep higher on boost, take the trim more positve (closer to zero).

 

[dsmluver98]

wow alright i am starting to get this ha ha.. but still need a few things clarified :/ how are you figuring out how much larger the injectors are in percentage? how come i need the low end in fuel trims to be +7 in order for it to idle correctly? is it the BC 272/272? Another thing i have been told to switch to a 2g maf with my set up how do you guys feel bout that or would it be better to switch to a MAFT and GM sensor because im going to switch to link when i get the money

 

[Chicken Patty]

It's a simple formula used to calculate injector compensation I'm at work and posting from my phone so I'll leave that as homework for you, but that's it. As far as idle I am not too sure, I always had to pull fuel. If you have it at anything less than +7 on idle what does it do? Goes lean?

And as far as the sensor, I'd go with a 2G MAF then save up for DSM Link. Not a fan of running a GM MAF with an AFC and a translator. Had it, disliked it. If you plan on getting DSM Link eventually and you get V3 Full, then you can run the GM MAF with their cable and no translator. Like that it works the best and I can tell you from experience. DSM LINK IS ONE OF THE BEST INVESTMENTS YOU'll EVER MAKE FOR YOUR DSM!!!!

 

[jcart953]

alright i had my car tuned by JNZ tuning

Just a quick question: How did they tune your car because it was to my knowledge they didn't have a dyno anymore and were not doing that?I could be wrong but I swore they told me this last week?

 

[dsmluver98]

yea I tried to take it to +5 and it started leaning out..
were is the best place to get the pigtail for the 2g maf?

Just a quick question: How did they tune your car because it was to my knowledge they didn't have a dyno anymore and were not doing that?I could be wrong but I swore they told me this last week?

they did a street tune meaning they just drove it and went off my wide-band and also used a tmo logger.. Is that bad?

 

[Jon91TSi]

yea I tried to take it to +5 and it started leaning out..
were is the best place to get the pigtail for the 2g maf?



they did a street tune meaning they just drove it and went off my wide-band and also used a tmo logger.. Is that bad?

I would be willing to help you out if you're willing to make the drive.

 

[dsmluver98]

Jon I am going to my old house on Saturday night into Sunday which is in Allentown would you be willing to meet?

 

[Jon91TSi]

Jon I am going to my old house on Saturday night into Sunday which is in Allentown would you be willing to meet?

I'm headed to my mom's house Saturday evening to drop off a late Christmas present with my brother so I won't be available Saturday evening. Is the car drivable? I'm only about 30 minutes from the 78/100 split west on I-78 off the Strausstown exit.

 

[4g63Powered]

yea I tried to take it to +5 and it started leaning out..

Leaning out to what, exactly? And it wouldn't hurt to double check the wiring f you did not install it yourself.

they did a street tune meaning they just drove it and went off my wide-band and also used a tmo logger.. Is that bad?

No, not as good as a dyno tune where you have better control of the variables, but they work.

were is the best place to get the pigtail for the 2g maf?

parts yard, the classifieds here, or a vendor. DSM Graveyard sells pigtails.

 

[dsmluver98]

It leans out to blank and acts like it wants to stall i believe but that could be the loping of the 272/272

Pigtail info. thanks Ill contact Jon then I am good friends i didn't know they did pigtails though.