S-AFC Settings W/ 625 - 660cc injectors

[big reg]

I recently installed a set of 650cc injectors in my 98 gsx along w a S-AFC. Could everyone with 625-660cc injectors post their settings for both lo and high throttle so i can baseline my car. Right now i have a 19c Frank jr but im having my Mutt level 2 installed soon and im just looking for some basic settings to get started. I also have 546\547 Web cams, big Greddy frontmount, ported 02 sensor housing and manifold, dsm-performance pulleys and 3" intake pipe, Apexi GTspec downpipe, no cat with Apexi dunk exhaust and Power intake and a few other things. I'm going to tune for 20 psi on pump gas, 94 octane by the way. Your help is greatly appreciated.

Later,
Reg

[Peter 92TSI]

Hey, it's hard to really identify specific settings, as even though 2 cars are similiary modded, the enviorment, and specific mods, especially since all injectors aren't created equal. ;)

But with that combo, I would say under high settings start at around -10-0% all across the board, and probably around --20 at idle, then do some light pulls, and watch the AF gauge. Better yet, if you have access to a datalogger, that will help a lot. I am not too familiar with OBD-II dataloggers, but I don't think if will give you knock sum, but it should give you timing advance, and from that you can seriously best tune the AFC and other settings. Shoot for at least 25% + Timing advance.

Other, best way would be, if you have an EGT gauge, tune to a *bit* below 900C, and make a linear fuel curve through the rpms.

Peter

[Cooter]

here's my two cents...


first... its a maf type injection system, what this means is the computer meter's fuel directly to the amount of air that is entering the engine....

second... your running injectors that are approximately 32% larger than stock....{440/650=.676~.68, 440/650 = .68/1 so if you subtract .68 from 1 you get .32, .32*100=32% difference. were you paying attention that day in algebra?) assuming stock injectors are 440cc, this is what i've been told, i have never actually read anywhere in the factory manuals what the flow rate is at base fuel pressure, (but when i put 550cc's into a 2nd gen car i set the afc to -20% across the board at high and low throttle positions and adjust the 1000 rpm band to get the best idle, and this works very well.) and to my knowledge that info is not in the factory manual, if it is in there somewhere let me know where, (i have manuals on cd-rom for both first and second gen cars.) also take into account that your injectors may be rated at a different base fuel pressure than stock and you will need to make changes as nessecary (this information should have been included in the paperwork for the injectors). the only other variable that i can think of off hand is sometimes injector flow curves are different from manufacturer to manufacturer... for example at 90% duty cycle your stock injectors flow 440cc/min. and at 90% duty cycle your new ones flow 650cc/min. but at 45% duty cycle your stockers flow 220cc/min and your big ones flow 300cc/min... (note the difference, at 45% you should see 325cc/min from the big ones assuming both flow curves are the same) i have only seen this on certain types of injectors, your stockers are denso's... if your aftermarket's are denso's also then they will flow on the same curve, only your 650's will flow 32% more... we've run into this problem once, and i can't even identify what kind of injectors they were (the shop that installed them ground all the numbers and identification marks off of them.....?) what this did was create a lean condition at moderate pulsewidths, and a rich condition at higher pulsewidths... you probably won't have to worry about this, but i'm trying to cover all the bases....


so.... assuming that you don't have some sort of weird hacked maf you need to take somewhere in the neighborhood of 32% out of your entire fuel curve, otherwise your going to run into a rich condition.... assume that with cams its goanna need a tiny bit more fuel and the porting will help scavenge exhaust gasses so add a little bit more there... your intake temps are goanna be a little lower (a lot lower in some situations) because of the front mount... so figure a little bit more fuel there.... if it were me i'd start with like -28% across the board and tune on egt's... probably leaning things out to somewhere around 29-30% across the board...

my car runs 1650- 1700 deg. F (930ish deg. C) at the top of third, and the plugs are some of the cleanest i've ever seen... i also have a first gen car and my probe is in the #1 runner close to the collector.... i also run straight 104 unleaded all the time.... so on 93 octane i'd shoot for 1600- 1650 (900ish deg. C), to be on the safe side... if possible keep a close eye on the fuel pressure, you NEED to raise it by 1 psi for every psi of positive manifold pressure to keep the injector flow rate constant...

the stock fuel map is set to keep a/f ratios at a certain # depending on manifold pressure, rpm, and a whole lot of other parameters... and the stock fuel maps are tuned very good, meaning that you shouldn't have to do too much tweaking to get the desired #'s from your car... you should end up with a fairly flat fuel curve all the way across the board... in both low and high tp, maybe adding a little bit more on the top end than the bottom....

This is how I tune cars.... I'm not saying this is the absolute right way to do it, but it works well for me... i've never blown one up by tuning this way. i've tuned several dsm's including a very wild 98 GSX, and i will tell you that most of the time, unless there are a LOT of mods done to increase the efficiency of the head and intake and exhaust manifold all you have to do is compensate for the larger injectors, and at low throttle positions the computer is automatically going to be in closed loop mode and adjust the fuel curve accordingly (to a certain degree, the stock computer can not compensate for a mis-tune thats 50% off). so your low throttle fuel curve is not going to be as important as your high fuel curve, i set throttle points at 30% and 70%, low and high respectively. The only OBDII car that i've ever worked on that had cams in it had HUGE idle issues, especially when you started adjusting the cam gears, an apex itc helped this tremendously, and it actually held a decent idle with HKS 272 cams in it.. about 1100rpm and had this nasty sounding lope at idle... was kick ass...

well, thats probably more than two cents, but i think that will help you out a lot and at least get you in the ballpark... if you haven't noticed i've had a lot of experience tuning dsm's (as well as other cars) and i have a lot of seat time doing third gear pulls in the industrial park behind the shop playing with the fuel maps (iwouldn't suggest doing 100mph on the street though).... the ONLY way to know FOR SURE is to get a GOOD lambda meter (if you don't spend $1500 or more *retail* for it its not the real thing, an autometer a/f gauge is fucking USELESS, egt's are the best way to do it otherwise, and some sort of monitoring device (snap-on diagnostics machine for example) to watch things like knock retard, and total ignition timing, you have an OBDII car which actually works in your favor when tryin to tune because the computer knows if your car has ANY little thing wrong) with a wideband o2 sensor (5 wires coming out of it) mounted as close to the turbine outlet as possible. dyno runs are almost certainly out of the question, and i've found that conditions on a dyno and conditions on the street are so different that most times your settings that you find work great on the dyno will be a LONG way off when you get it on the road/track, there is ALWAYS more load on the car on the street and generally the whole powertrain runs significantly cooler (we have plotted charts from and extensive temperature datalogging system that proves beyond a shadow of a doubt.)

ok.. i'm done... good luck, get a friend to help you, to hold onto the diagnostic machine, and watch gauges or the diagnostic machine,trying to do it yourself is suicide... hope this helps...

Cooter
http://www.sound-performance.com

[big reg]

Holy shit Cooter, i think you just taught me more in the minute it took me to read that than any algebra class. My car wont be up and running for another couple of weeks as im still either installing stuff or in the process of having it installed. Also, have any of you guys had any experience with the new Greddy A/F ratio gauge. It supposedly reads your exact air/fuel ratio and comes with its own heated o2 sensor bung that needs to be welded either in the o2 sensor housing or downpipe. It's like $300 so I just wanted to know if it was usefull or accurate i should say or a pos like the auto meter gauge that swings to farthest right led at anything over 3800 rpms. Once again thanks guys, I really appreciate it.

Later,
Reg

[Peter 92TSI]

Wow Cooter. Nice response man. :)


IF you want a fairly cheap AF Gauge, the best thing, in terms of a cheap solution would be a digitial voltmeter, like a Jumprtronix AF Gauge, that reads out specific o2 Voltages. Although, without a *real* o2 sensor, (the stock isn't 100% accurate), but usually for a 2G on 93 pump gas you should tune the magic number of .90V. You could aslo do the blue wire mod on the AFC, where you connect the blue wire to the o2 voltage on the ECU harness, and then under ETC, sensors, on the AFC you can get the same reading. A bit more diffucult to read, but obviously free if you already have an AFC.

I think cooter covered everything extremely well, but I must disagree a bit on tuning to 930C, that is getting a bit too hot for my liking. Running at that temperature for a long period of time might not be too nice on your engine internals, meaning some of them, specifically the aluminum parts, especially if you start to detonate *might* start to melt. I personally would shoot for a bit under 900C. Most DSMers tune to hit 900 right when they cross the line. Granted when running higher fuels like a 100 octane, that number can be extended a bit, but like you said, you are running 94 pump gas.

Peter

[DSMu4ia]

You can get a A/F gauge that reads your exact 02's from here:

http://www.gadgetseller.com

He can also modify your original one so that it reads exact as well. Hope this helps.

[Cooter]

the greddy a/f gauge is actually extremely accurate, it needs periodic adjustment though, jarret at powerhouse racing in texas said that once the gauge was dialed in (there is an adjustment knob on the brain unit) it was extremely accurate, reading within like 5% of a motec sniffer...

as for egt's... most of the time i'm pushing the absolute limit (the reason for straight 104 octane all the time)... but my cars always seem to last longer when they're runnning on the edge, when i try to baby them they break... figure that one out... but anyways, i always make sure everything is in good order before putting the throttle to the floor and holding it there, and to be honest, i hardly ever get into my car for any more time than it takes to pass the grandma in the station wagon goin 35 mph on the highway in the far left lane... although i like to whack the kid in the civic that thinks he's goanna take out my 'pile of shit' talon (its not the prettiest thing, but it runs like a champ).... 890ish deg. C is safe.. for most people in their cars they aren't worried about the extra 10-12 hp that a little leaner will get them, and most don't want to risk melting pistons... personally if i blow it up, that just means i get to put better stuff in it... and you can bet that when my stock block goes its not goannna be because of a lean condition, its goanna be because the internals just couldn't take the pressure...

Cooter
http://www.sound-performance.com

[fourg63]

Hi Cooter,
Welcome to DSM talk.I didn't know you owned a DSM.
Anyway great response on the AFC settings.Say HI to Larry, Gary, and the rest of the crew for me.
I'll stop by once I get my car on the road again.

Later,
Mario

[Cooter]

whats up Mario? long time no see... yah i picked up a 90 awd.. its a lot of fun.. got some kewl stuff goin on.. and lots of kewl ideas... i'll tell everyone you said hi..

what are you doing to that thing now? and how's Norbert's 240 runnning?


talk to you later man,

Cooter
http://www.sound-performance.com

[fourg63]

Well.I took the turbo off cuz TAD never portmatched it.Same with the throttle body and intake mani.Had everything portmatched.I installed -6AN lines,Fluidyne radiator,Tial wastegate.Waiting for some other small stuff to come in.
Norbert's car is running but he doesn't want to drive it with hail damage and all.He's waiting for a body kit from Japan and will probably not drive it this year.You guys get that Dyno yet? I heard you were gonna move to a bigger shop.How's that coming along?
Anyway I got a question.Do you guys know of anyone that does chrome plating? I need this one little piece plated and can't find anyone who does it.Let me know.

Later,
Mario

[Cooter]

theres a place called personal touch in streamwood? (its either streamwood or schaumburg there?)... its in the 4b complex off barrington rd, in the back... he takes forever and a day to do it, but he does a good job... his name is jay, tell him your one of our customers and he'll take care of you. all you gotta do is go there when he's open... its kinda hard to catch him at the shop...i really don't know the best times to try, but larry usually goes in the afternoon, in the middle of the week..

we're actually moving soon down to the end unit in the building we're in now... and a dyno will soon follow.. we're looking at a mustang dyno.. with all the bells and whistles... blows the dynojet away... goanna be kick ass..

Cooter
http://www.sound-performance.com

[fourg63]

Yea.I heard of them.I thought they only did polishing.
Thanks

[Le Talon]

Great explanation, but you have to keep in mind that DSM's (especially 2G's) are tuned quite rich from the factory. So for a more power friendly curve, you might end up removing a little more fuel at WOT...

On the PMS, I started exactly like you said for tuning for my 720s but ended up adding some fuel (removing less in fact) at idle and low throttle to keep the fuel trims happy. But the PMS has its own injectors driver (so I've been told) so its effect might be a bit different than the AFC...

[DSMu4ia]

Just as a side note:

Walbro 255, RC 550 injectors..

Old style AFC, MAS Screw Flush, center and side honeycombs out.

-30% on all trims besides idle..and that's only because after the removal of the honeycombs she wouldn't idle.

02's are .96
EGT's never go past 1500F

[fourg63]

DSMu4ia.I think you can go a little leaner there.Oh wait you got the old AFC.That thing only goes down to 30% right?
You're running fairly rich with those 550s and Walbro even with the honeycombs out.Damn.Have you tried lowering your fuel pressure with an aftermarket FPR?

[DSMu4ia]

I'd love to go leaner..Buschurs said 325whp with a S-AFC but wheels had to come first. I would rather get a S-AFC than a FPR..but I'm gonna go with a complete rebuild this winter with a STEVETEK fuel system, etc. I would love to have a S-AFC..but like..the old style is so much easier to adjust..no high/low pots..just turn and burn. I'm pretty drunk right now..but I was doing 1-4th gear runs and never saw past 1450F...damn I'm rich. I could only imagine what a 1550F pull would feel like. 2nd gear as the car sits right now is too much unless I'm totally paying attention. Car pulls like a SOB regardless....maybe I'll have one..depends on how much $$$ I make this month.

[turbo21psi]

Cooter basically explained everything but for comparison sake this is what I'm running.
I have 660cc's and a 255 HP pump, lower honeycomb removed.
Stock turbo, Stock IC only 17psi
My Hi settings for the S-AFC are:(from memory, but should be pretty close)
3K -32%
3.5K -32%
4K -30%
5K -28%
6K -25%
7K -25%
I'm also still in the process of tuning the car so these settings will probably change. With these settings, I did a 3rd gear pull to 6500 and my EGT was around 830C. I think I might be able to lean it out a bit more but I'm trying to play it safe. The reason I had 6-7K a bit rich is that when I have the AFC set at -30 across the board, I would have knock sums of around 20-24 past 5K, but my timing is still at around 17-20 deg at the top.

[Cazzo]

With 660's and a denso f/p, 70 degree external temp- 19psi boost, 92 octane.

Hi -35% -35% -32% -32% -32% -32% -32%

lo -15% -20% 3-7k -25%

[Gruss]

I got the Dejon 3" intake with extra K&N which increases the air bypassed by the MAF 30%. I also have 650cc injectors (32% more fuel). So I run around -3 to -10% on low throttle depending on the time of year, and -10% at the start of high throttle and +5% by the end. I end up running near 80% injector duty cycle with the T3/T4 @ 20psi and on 93 octane.....

[teameXplicit]

hey guys, I just installed my SAFC today I have the stock injectors in right now going to put in the 660s this weakend..but my question is I set the HI and Lo settings on 0 across the board just so I can drive the car. My problem is the car won't start... I thought if the settings were @ 0 it would be like the SAFC was off. Am I wrong? Could you guys could give me some advice what should the settings be.
here are my mods: 1G
TRE 16G turbo
D.S.S. Front Mount Intercooler
HKS Upper Intercooler Piping
Greddy Blow Off Valve
Ported 95 manny
Ported O2 sensor
3 angle valve job
Mild Port Head
2.5" downpipe
3" thermal exhaust
Nippon Denso fuel pump-Thanks

[95GST]

Yes you are right, keep it as 0 will be like you never installed it.

If it won't start it maybe some wiring you messed up, another thing to check is to turn the key to ON position (not START) and make sure 4 cyclinders and all that stuff is selected. Check out the RRE site for more details

Originally posted by teameXplicit
hey guys, I just installed my SAFC today I have the stock injectors in right now going to put in the 660s this weakend..but my question is I set the HI and Lo settings on 0 across the board just so I can drive the car. My problem is the car won't start... I thought if the settings were @ 0 it would be like the SAFC was off. Am I wrong? Could you guys could give me some advice what should the settings be.
here are my mods: 1G
TRE 16G turbo
D.S.S. Front Mount Intercooler
HKS Upper Intercooler Piping
Greddy Blow Off Valve
Ported 95 manny
Ported O2 sensor
3 angle valve job
Mild Port Head
2.5" downpipe
3" thermal exhaust
Nippon Denso fuel pump-Thanks

[teameXplicit]

Sorry guys it was my TMO ecu I have had the security mode tuned off for months now...when I rest the ecu the security setting came back also.(da) It runs fine. Thanks for the reply.