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Miami240
03-13-2003, 05:51 PM
My buddy put in some 370cc injectors to supply fuel for his KA-T. He has no fuel management. He just bought an SAFC and needs to know how much to turn them down just to get the car running pretty normal. He'll fine tune it after that.

DETeatsvipers
03-13-2003, 05:52 PM
is it even instaled on the car yet?

VeilSideS14
03-13-2003, 05:59 PM
If he just wants to get the car running "pretty normal" then he can do it by guess-n-check method. Read the directions and it'll tell you how to decrease the fuel at each RPM range.

Miami240
03-13-2003, 06:04 PM
He says he's read the instructions and they are waaaay too complicated. I know someone knows how much to tune them down because i remember reading it somewhere. I just can't find it now.

VeilSideS14
03-13-2003, 06:07 PM
The thing only has 6 buttons on it. If he thinks it's waaaayyy too complicated, he should bring it somewhere and have them do it.

Hugh
03-13-2003, 06:19 PM
The thing only has 6 buttons on it. If he thinks it's waaaayyy too complicated, he should bring it somewhere and have them do it.



Don't harass the guy just because you don't know how to do it. It only has six buttons but a ****load of menus are controlled by those six buttons.

Try turning it down to -27% across the board. Turn the low throttle point to zero and set low throttle map all to -27%, then set the high throttle to maybe %50 and the whole map to -27%. Now start tuning or down up from there.

The numbers work sometimes, other times they need a little tweaking. You have to cut it down around idle... say keeping the DEC AIR setting NE1 turned down pretty low with a 1.0% throttle or something like that.

VeilSideS14
03-13-2003, 06:27 PM
Don't harass the guy just because you don't know how to do it. It only has six buttons but a ****load of menus are controlled by those six buttons.



Well, I've done it before so yes, I do know how to do it. If you don't know how to figure out that the 370's are 27% larger and you can't figure out how to account for this given the 6 buttons on the unit and the instruction manual, you shouldn't be messing with it. It's not harassment. It's directing him to someone who can help.

Hugh
03-13-2003, 06:29 PM
Don't lie, you just didn't want to do the math.

VeilSideS14
03-13-2003, 06:32 PM
You guessed it. Math is the scary beast that haunts me while I try to sleep. Mommy!! Make it stop!! http://forums.freshalloy.com/images/graemlins/frown.gif

Cause after all, you needed to do some triple-integrals with hyperbolic-cosines to figure that out, right? If it only were as easy as simple division, I would have done it.

Hugh
03-13-2003, 06:36 PM
Is there a sense of humor in there? http://forums.freshalloy.com/images/graemlins/confused.gif

VeilSideS14
03-13-2003, 06:42 PM
Please tell me you aren't serious when you ask me that question. Just in case you are really clueless, no, there was no humor, but loads of sarcasm.

Anyway, to bring this back on topic, any tool that alters your fuel/air ratio has the ability to mess up your engine if you don't know what you're doing. Make sure that after you get the car running stable enough to drive, you get it to someone that has the tools and knowledge to tune it correctly.

Miami240
03-13-2003, 09:29 PM
Thank you 1Bad180sx for helping me out and not giving me [censored] about it.

Kookz
03-13-2003, 10:53 PM
Thank you 1Bad180sx for helping me out and not giving me [censored] about it.

HAHAHAHA, "my buddy"!

orion
03-14-2003, 10:14 AM
If you don't know how to figure out that the 370's are 27% larger...



The 370cc injectors are actually 37% larger - I made the same mistake when calculating how big of a pipe I needed for my hacked MAF.

"[270/370 = .73], hence a 27% difference"...wrong.

The increase in size is [270 * x = 370], 370/270 = .37

Just so no one is confused...

And as for the % change on the AFC...I dunno if it should reflect the exact % change in size increase or if you do the math backwards...i.e is it the decrease needed to effectively bring the size back to stock...? So with 370s you need to back off 27% of the fuel to reach 270cc --> 370*(1-.27)=270. That makes sense...

Disclaimer - I haven't ever messed with an AFC. If 27% is a tried and trued baseline, great. And it makes sense mathematically. But go by what others with AFC tuning knowledge say!!!

Someone please let us know...

Later - Brian

Hugh
03-14-2003, 11:47 AM
It doesn't matter what is what size of what. You said it yourself, you have to make it reflect stock... so beofre you confuse the sht out of the guy...


-27 should work. If its way off... try -37%. http://forums.freshalloy.com/images/graemlins/grin.gif

Rownan
03-14-2003, 12:24 PM
It doesn't matter what is what size of what. You said it yourself, you have to make it reflect stock... so beofre you confuse the sht out of the guy...


-27 should work. If its way off... try -37%. http://forums.freshalloy.com/images/graemlins/grin.gif



A bigger mafs will not only allow more air to enter, but it would also accelerate the air to a degree wouldn't it? So you gotta factor that in.

I am just saying that any length of calculation will be off a little, so it is best to take a safe number and go from there. You definitely don't want to be too lean, but going to the bigger injectors I don't think you'll have to worry about damaging anything when you start it up.

I'm actually going to be running into this same dilemma soon, I have a S-AFC and as soon as I find a Z32 MAFS I'll be hooking it up to my 11:1 compression KA and seeing how deep the rabbit hole goes..


Tim
www.projectaspec.com (http://www.projectaspec.com)

Kookz
03-14-2003, 01:02 PM
Hooking up a MAFS is as simple as telling the S-AFC what you put on and what it's replacing. Injectors you choose the percentage.

Logically, -27% would be a good bet, as you're basically telling the ECU to reduce open time of the injectors 27%. That would make 370s run like 270s.

ziggy682
03-14-2003, 02:00 PM
I have 370cc injectors in my KA, and my SAFC is tuned to -27% accross the board. It runs just like stock. I was a bit confused with the math at first, and tried -37%, and it ran very lean. -27% is the number to use. Also, I have low throttle set at 10% and high throttle set at 50%.

orion
03-14-2003, 02:57 PM
A bigger mafs will not only allow more air to enter, but it would also accelerate the air to a degree wouldn't it? So you gotta factor that in...



Bigger MAF = Slower air speed...and as Kookaburaz said, the AFC makes the MAF work plug-and-play if it's on the list, you just worry anout the fuel.

And 27% is definitely the baseline #. I re-read my post above and it does look confusing. So the correct, simple statement is "For tuning an AFC, you base the % change on the new injector size...". i.e. 370cc minus 27% = ~270cc.

Later - Brian

Rownan
03-14-2003, 03:20 PM
A bigger mafs will not only allow more air to enter, but it would also accelerate the air to a degree wouldn't it? So you gotta factor that in...



Bigger MAF = Slower air speed...and as Kookaburaz said, the AFC makes the MAF work plug-and-play if it's on the list, you just worry anout the fuel.

And 27% is definitely the baseline #. I re-read my post above and it does look confusing. So the correct, simple statement is "For tuning an AFC, you base the % change on the new injector size...". i.e. 370cc minus 27% = ~270cc.

Later - Brian



Really? I thought that the S-AFC would simply allow the ECU to understand the signal coming from the MAFS, not actually convert the signal for normal operation.

You can't even BEGIN to know how happy that makes me!

orion
03-14-2003, 04:10 PM
Again, I have no first hand experience with an AFC, but from what I've read, that how it works.

I'm sure someone will correct me if I'm wrong.

Later - Brian

KASilviaAR
03-14-2003, 06:22 PM
A bigger mafs will not only allow more air to enter, but it would also accelerate the air to a degree wouldn't it? So you gotta factor that in.




Exactly the opposite, actually - a larger opening will yield a decrease in intake velocity, given the same volume of air. The larger MAFS simply creates less head loss in the intake system, thereby increasing efficiency.

Hugh
03-14-2003, 07:39 PM
OK, so, Gumby Style, this is what you get.

To factor the % on an SAFC, you have to figure out what % the 270cc injectors are in relation to the new injectors. My math is correct, and if you run 370cc injectors at -27%, they act like 270cc. I'm happy someone is actually running this and it works.

To change air flow meters, you go into the menu for hot wire air flow meters and select which input and output signals you want.

Example: Z32 air flow meter is a '2' input. SR20DET is a '6' output. I don't know first hand what the KA is looking for... I can only speculate its '7' like the CA18.

My ECU is tuned for a Z32 MAF, and I am using a Q45 MAF... so my settings are Hot Wire 1 In 2 Out. (Q45 is 1, Z32 is 2)

The SAFC adjusts everything for you from there. It will require a change to your decel air settings if you're using that option. My car acts really funny with the Q45 MAF... It was already stalling enough with the Z32 MAF installed, but I like the power. Just be warned, the bigger you go - the less % is required for Decel Air.

The AIr FLow % read by the SAFC is actually the % of max flow that your MAF can handle. If you are seeing 90% and higher, you need a bigger MAF. I maxed the SR MAF with a stock turbo. I then maxed an RB20 MAF at 10psi on my T04E. I never saw over 70% on a Z32, and now I am seeing over 80% on a Q45. (it's the biggest available) So for me its time to move to a computer with no MAF... I am installing a Tec3 within a week or two.

ETfukuoka
06-05-2003, 02:12 PM
brought this one back from the dead!! I just got a new/used Safc from a Yahoo Japan auction!! I am stooked. i am picking up my Z32 and injectors this friday. I downloaded the Apexi manual and that bugga is like 50 pages!!
I have read it once and will probably read it again many times. Now my Question:

My motor is a Red Top JDM (S13 Silvia). It is stock except for a HKS BOV and a Trust man. boost controller, exhaust system. With the Safc, Z32 MAF, and 444cc or 550cc injectors, stock SR fuel pump can i run 1.0 bar??? Eventually, i will get a Tomei fuel pump, and FMIC (its a money thing LOL). Thanks for any advise or Safc tuning advise you can give.