edomund

OK just to make sure I fully understand how to tune the s-afc.

Am I correct saying that where you set the hi throttle %, lets say 80%, anytime you are above 80% throttle (or pressure) the s-afc uses 100% of the high numbers?

So if I set hi at 80%, when I'm at 81%, and I set the hi map like so (just for example)
2k 3k 4k 5k 6k
0 +2 +2 +4 +6

Now if I'm at 81% (or anything above that) when I'm at 2k it uses 0, 3k +2, 4k +2, 5k +4, and 6k +6, correct?

Now if I am below 80% it uses a percentage of those numbers until I am below the lo point then it uses th lo #'s, correct?

Is my thinking correct?

gsracer

exactly.

edomund

Thanks!
Now I get to go dyno Tuesday!

gsracer have you dynoed with your s-afc like this?
If so can you post the dyno chart and your s-afc settings for referance.

incendui

Most of this is a repeat of what cheers said, but this is how I got my safcII to learn the full voltage range of the pressure sensor.

First I turned the car on, but not running, and switched the safc to the etc mode, so i could see the voltage value of the "throttle" input. According to the manual it needs to read the high and low settings for 10 seconds to learn it, so I attached a bicycle pump to the pressure sensor (a vacuum line fits perfectly in the other end of a tire stem I had, it was called the monkey grip or something, got it from autozone), and held the sensor at > 4.5v (~14psi) for 10 seconds, the safc set that as 100% throttle. Make sure to turn the car off before you start it, otherwise the settings wont be saved. When I drove the car around afterwards, the safc set the 0% thottle at something slightly lower than the idle vacuum, so now I have a good range from around 3% at idle, to 55% at 5psi.

Cheers!

Did you have the wire on the TPS sensor before you moved it over to the pressure sensor? did you reset your safc before you moved the wire over?

I don't understand why people say the safc doesn't self learn. It's not self learn it's calibrate. NOT every single automotive OEM TPS is 0 to 5V in range some maybe different. Which ones i don't know.

To the person who posted the safc doesn't self calibrate. Could you please care to elaborate? please? i would really really like to know.

I have found that it self calibrates. So does scott 89T2. from his website.

1300cc.com

and i quote...
"***update***

After swaping TBs last week (tb mod) and removing the vac rack etc. I had to adjust the TPS and idle as expected. What I noticed today was now my S-afc was only reading 86% at WOT. It was still trying to read the same TPS voltages that it was adjusted to before. so I needed to recalibrate it... after some screwing around.(with the car not running, but key to "ON" I went into the section where you choose it. (car type) with the arrow up. I changed it to ** for no reading and went back to the main screen. Then back to car type and changed it back to the correct setting arrow up. Went back to moniter and sure enough it hit 100% at about 3/4 throttle. A few more times pressing and it had recalibrated itself so 100% was 100%.

This is Just a note for S5 users. if you ever re-adjust your TPS. you might need to do this. "

reference page:
very bottom of
http://1300cc.com/howto/how2/safc.htm

when it comes to rx7s and S5 TIIs i trust scott a lot he knows his ****. I know it self calibrates because that is what i observed.

Cheers!

Yes someone who agrees with me. Way to go... maybe put a poteniohmeter in there instead so you can just turn a dial.

Cheers!

If you add more resistors in line to make say 8 psi = 90% throttle it woudl be better.

The safc functions off of 3 maps.

Low map is anything under your low throttle point %. Forexample.

you set low = 30% throttle. the map it used below 30% is fixed constant correction.

High map is again constant correction. so if you set high = 90% anything above 90% gets corrected to fixed amounts = to your last correction that the safc used at the RPM before

Medium map (my term): anything between 30% and 90%.

During this, it will interpolate the map between low and high.

This is how i believe the safc works.

Please feel free to correct me if i'm wrong

incendui

You dont need resistors to get the safc to learn the entire range of the pressure sensor. Just attach a pump to the presure sensor when the car isnt running, and hold the max pressure value for more the 10 seconds. Then turn the car off before you start it. The settings will be saved.

I did this without ever running the car off of the TPS, and it works fine.

gsracer

Yes, that is how the safc works. I have the low map set up to 98 percent and the high map switch at 99 percent. The low map is entirely stock all across the board, and the high map is when I start adding in fuel.

I thought about that, but I figured that until I get the car on a dyno I would let the stock ecu do what it wants under fuel cut. Obviously mazda figured it could handle anything up to 8.6psi, so up until 8 pounds I'll leave it stock. After that I'm probably going to be needing more fuel so that's why I have it switch over to the high throttle map over that.

8 pounds is about the limit of what I would trust the primaries to handle before the secondaries come online as well. If I set the limit to 8 pounds and I boost more than that before the secondaries come online, I can add start adding fuel under 3800 rpm. As it stands, I don't know how much more fuel I can add before I max out the injectors but I'll find that out soon once I can get the car on a dyno.

I've had the car on a dyno running 10.5 pounds on the stock ecu. I have a pair of 720's sitting on my desk at home that should be going in soon. Hopefully over the christmas break I'll get the chance to get those in and take it to the dyno. I'm gonig to shoot for 240 rwhp@12 pounds; I'll probably retard overall timing 2-3 degrees just to play it safe. I'd be scared to push the stock IC too much over 12 pounds as it is. I'll post my safc settings and dyno no matter what goes on once it happens.

surfpac

I did the pressure sensor mod instead of using TPS. This is used to swith over to the high setting map at a predefined % setpoint. I used a didgital pressure sensor that has an anolog linear voltage output dependent on pressure (range 0 psi - 145 psi). I have my SAFC2 high throttle map set to come on at 13% throttle percent (which is around 8 psi). Below 13%, I'm runningo nthe low settings. The manual for the unit is poorly written and I had to go online to figure this out. I have this on my SR powered 240SX and so far is works great. All you ned t do is go on a dyno and fine tune it with a wide band sensor. I highly recommend the SAFC2 with the pressure sensor mod. You could also use the MAP sensor from a Turbo 2 instead of the Motorola sensor.

jester1341

i hope someone is still checking back on this thread. my TII has a SAFC and i have a SAFCII im going to install in the spring and go righ to the dyno. now i read all this, but i need it kept in mind that my car is a daily driver and hopfully will be on the strip maybe once a month.

that said what is the most practical way to wire the SAFCII so that it won't go into 'high' when im crusing.......in other words what is the most "non-drastic" way to make pedal down when i hit 100% throttle??

incendui

If you use the pressure signal instead of the tps, then the high map will only come on once youre seeing boost. That shouldnt happen while youre just cruising, and if it does, then chances are you need the extra fuel anyway.

Cheers!

Don't hit the gas pedal so hard then.

surfpac

You got the idea!! I used the MAP mod as well instead of TPS to switch on to the High Throttle map. I didn't use any regular map sensor but rather I used a digital pressure sensor/switch that has an analog voltage output from 0-145psi. Voltage linearly increases from 1V - 5v across that 145psi range. Hence, I set my high throttle switch-on point at 13% which corresponds to about 8 or 9 psi. I've been using this now for over 6 months and so far so good, no problems at all. It's easy to adjust. I'm using this on my SR20 powered 240SX but the concept is the same on any vehicle. Here's a pic of SAFC with the digital sensor

surfpac

You got the idea!! I used the MAP mod as well instead of TPS to switch on to the High Throttle map. I didn't use any regular map sensor but rather I used a digital pressure sensor/switch that has an analog voltage output from 0-145psi. Voltage linearly increases from 1V - 5v across that 145psi range. Hence, I set my high throttle switch-on point at 13% which corresponds to about 8 or 9 psi. I've been using this now for over 6 months and so far so good, no problems at all. It's easy to adjust. I'm using this on my SR20 powered 240SX but the concept is the same on any vehicle. Here's a pic of SAFC with the digital sensor

jester1341

thats very clean, i like it. so the digital sensor gets its signal from the MAP and then the SAFC gets its signal from the dgi sensor.......


i get the basic principal behind switching to high throttle corrosponding to boost pressure, but i kinda get lost in the mechanics behind getting it done.

turbo makes boost causing pressure......this "devices" converts pressure into a certain voltage that increases linearly from 1V-5V baised on a 0-145psi scale.......that certain voltage is then sent to the SAFC on the throttle position wire. is this basicly how it works??

if so does that mean that ultimatly your throttle read out becomes an uncalibrated boost gauge??

YearsOfDecay

This is EXACTLY what you NOT NOT want to do.......

you WANT the FCD to cut the signal BEFORE the S-AFC gets it....

you leave the FCD on.... (you have to tap the throttle signal from the FCD into the boost signal at the ECU AFTER the FCD) The S-AFC will learn that 3.64 volts (if using my FCD's) is 100% boost (factory boost) you then set up the S-AFC to start dumping in fuel by RPM after the FCD flatlines..... In essence, then, your S-AFC is displaying a % of the max stock boost on the screen in the place of the throttle.

Then you set the high range limit to 95%.

Your stock computer will add fuel up to about 8.5 PSI, at that point, the SAFC will start adding more fuel by RPM as to the map that you programmed into it.

I had this system on my 88TII until i went haltech.. it works extremely well as long as you set your S-AFC using a wideband O2.

My High range Map didn't start adding fuel until about 3K RPM because I neve saw boost over the stock limit until much higher....

Since the stock ECU is designed to handle boost up to 8.6 PSI... let it... it will increase your overall efficiency.

gsracer

I disagree, there's no point in not just soldering it in before the FCD. I have the hi-thrtle switch around 10 pounds, on a dyno I've found the stock ecu can handle the fuel demands just fine up to this point using a dyno that was equipped with a dyno.


While there is no disadvantage of limiting the amount of boost pressure being seen by the safc to be 8.6 pounds, there's also no disadvantage in using the full limit of the stock pressure sensor since the hi and lo thrtle amounts can be set at any place(1bar) I do have a similar set up to what you had. Stock ecu with no corrections via the safc until the hi-thrtle switch over.

YearsOfDecay

I think you an I are doing the exact same thing, just in different ways!!!!! you are using the full range of the boost sensor BEFORE the FCD and then settting the hi throttle to take over at the appropriate point in the boost range. I'm taking the signal AFTER the FCD and then setting the Hi Throttle at to come in at virtually the same point by setting it at 95% of max (of 8.6).

Yours might be a bit more adjustable during the area where the ECU is the primary controller. Below 8.6 PSI

My way makes it easier to know WHEN the ECU has reached its limit. 100% of the boost signal after the FCD is just about 8.6 Lbs of boost, the high limit of the ECU's range.

I did it my way for two reasons.. 1) ease of setup... (you know that 100% signal is where the ECU is ging to stop seeing more boost) 2) don't have to run a wire through the firewall to the FCD!!!! I figured that if i had the carpet up and the ECU out, i didn't feel like messing with running ANOTERR wire through the firewall!!

I used a wideband and found that no matter what i did.. the ECU always kept the fuel right until 8.0 LBS of boost. So I let it!!! this is also why I set the S-AFC to 95%. I used a digital pressure sensor and applied compressed air through a regulator to the Boost sensor and found that 8.0 lbs (+ or - 1.5% as per the instrument) gives a reading of 95% throttle on the SAFC..

Setting the S-AFC this way gave me fuel curves on the data log with no noticeable spikes or drops over the transition from ECU to S-AFC!!

Both ways are going to work just fine... Its all up to personal preference and how tricky you want to get with the setup!

In Either setup... Your best friend should be the guy with the wideband!!!!!

YearsOfDecay

One Note: If you have'nt ported your wastegate, or ar having problems with boost spikes... then you really want to take the extra time and go with GSRacer and tap in BEFORE the FCD......

The reason being that doing it my way will result in you dumping in fuel dependant on RPM after the FCD kicks in... the is great if your boost remains constant through the RPM range as mine does. HOWEVER... if you are seeing lots of spikes and irregular boost patterns,,,, you really want to have the full range of the boost sensor handy as this will allow you to have a "cushion" for such instances. Its just gonna take longer to tune correctly!

jester1341

either way i need to get a boost guage soon!!

razorback

has anyone tried this yet?

JunpoweR

iTrader: (1)

soon i will put a s5 motor with street port that i am rebuilding with all emissions removed.SAFC2 and a AVCR with my wastegate ported on stock s5 turbo ll probably hit about 290rwhp(with propertuning on Dynopack).boosting at about 14-16psi(s5 stock turbo)
not sure which car this is going into my 90 champange gold gxl or my 89 GTUs.
Depends on which one I sell first for funds for my project.
More updates later.I will be using a boost pressure sensor for my Hi settings and TPS for under.this will be my daily\drift car =)

gxlbiscuit

i installed my SAFC2 saturday i dont know why these guys want to use another sensor. I soldered my SAfc into my FCD before the signal goes in the FCD box. my car works perfect.... so perfect i blew up my turbo(145k). at idle i see 0 to 3% on the throttle when i hit high boost it kicks in like its supposed to.. my low map is blank. silly rabbits.. K.I.S.S.

fstrnyou

double post, sorry