CRX7

Is using an SAFC one of the better choices for fuel control, i dont have stacks of cash and already spent what i have on intakes, gauges boost AF and water temp, as well as greddy FMIC and AST. I am now broke but need a fuel computer and can dishout a couple hundred for it. Is SAFC the best choice because after these mods the motor will run lean.

Mahjik

iTrader: (1)

I believe the SAFC will allow you to adjust your fuel mapping without a problem, however, it will not allow you to adjust timing or remove fuel cut from the stock ECU.

moehler

iTrader: (12)

I have no experiance with the SAFC, but you could find a used pettit or m2 ecu for a few hundered bucks.

POM HB

Remember that SAFC only add or reduce fuel that stock ecu decides the amount. So, you have to be sure about your boost level that it won't creep.

I was gonna do that years ago, but couldn't decide.

POM HB

MazdaRx7Racer4Life

You'll end up spending more money ( think) trying to get rid of fuel cut and boost creep afterwrds, save up a little more and get either a powerfc, or like POM Hb said, an M2 or petit ecu seems more than enough for your application.

kyle@insight

This is all hear-say for me so feel free to correct me if I'm wrong, but this is what I was told as to why you shouldn't use an SAFC on an FD.

Many people use them on TIIs and such to control fuel because the TII's secondary injectors come on at a predetermined RPM. It doesn't work that way on an FD, an FD is not RPM dependant, I believe it's load or boost dependant.... or possibly maybe even throttle dependant, my mind is a little fuzzy on this. Anyway, it's due to that reason that an SAFC is a bad idea on an FD, because there's no specific time that the secondary injectors come on, which can result in a very lean condition at lower RPMs.

Again, this is something i was told a while back, feel free to correct me if I'm wrong.

Either way, I say do it once and do it right. PFC or some other full ECU, not a cheap piggy-back.

MazdaRx7Racer4Life

I agree with you on that, theres a reason the fd community doesn't use the safc, which is relatively cheap compared to other fuel controllers. The PFC was made for the fd, as were the m2 and petit ecu, do it right the first time, that way you do't have to do it over, sometimes the cheap remedy to a problem turns out to be a problem itself, spend wisely.

CRX7

Where the hell am i to find a used ECU for less than my first born?

Mahjik

iTrader: (1)

CRX7,

Apparently, the SAFC does adjust timing, but indirectly. You should spend some time in the Super AFC forum as you will find answers to your questions there:

https://www.rx7club.com/super-afc-123/

rynberg

I've said it before, and I'll say it again. If you can't afford to mod the car, then DON'T DO IT! What is so HARD to understand about that?

The S-AFC is completely worthless on an FD. You still can't run higher than stock boost (10 psi) with it and the stock ecu runs rich enough at 10 psi for all of the bolt-ons.

If you are broke, install a manual boost controller, keep boost at 10 psi, and be done with it. If you wouldn't have spent money on worthless mods like an A/F gauge and FMIC, you could afford an ecu.

rajeevx7

iTrader: (11)

I love my PFS computer! Plug and play with maps already set for 10,12 & 15 psi. No tuning required, but probably helpfull. Bam...300+HP out the box.

Some cars do have a problem with fuel cut not getting canceled in 3rd gear but mine didn't.

Raj

rajeevx7

iTrader: (11)

Oh, and the commander has full logistic read outs and can adjust timing and fuel making it a dynamic computer to change with each new mod. Got mine for $250 out of the FS Section.

Raj

CRX7

hey rnberg, it will be ok, i have money, thats why i posted, trying to find the best choice here, but thanks for such a graceful reply.

rynberg

If you are being sarcastic, I did answer your question. As far as you having cash:

moehler

iTrader: (12)

go to the for sale forum... if you wait for a few weeks you'll get one. many people start with these ecu's and then switch to a pfc when they upgrade their car further. so you do see them for sale. you should be able to find one close to the price of a new SAFC. modding these cars is EXPENSIVE... keep that in mind. you change one little thing, and you have to change five other things to compensate for it.
as rynberg said, if you can't afford it, just get a boost controller and keep it at 10 psi.

rx7raca

safc is for NA cars, and older turbo model cars. its not made for the kind of power the fd can put out. bottom line, dont ever consider it.

CRX7

sounds goods, upgraded ecu it is then, thanks for the help

CRX7

but i do wonder this, with the mods i have i have been told the motor will run lean, which was my reasoning for the safc in the first place.

rynberg

Not true at 10 psi. Wade has done extensive a/f ratio testing and my own testing supports it.

rajeevx7

iTrader: (11)

Bunk that uprgraded computer crap. You want to have a stand alone or piggy back to have many different maps available.
You have to understand that an upgraded stock ecu to support 15 lbs will have you running rich untill you get all the mods that the computer was built for. Probably IC,Intake,Exhaust. Too rich = power loss+fouled plugs.
Any other comp. has the ability to change as you change your car.
Raj

maxcooper

The injector timing thing is an issue if you want to change the injector sizes. It is the reason why you can't change the ratio of primary:secondary injector sizes on the FD and expect to avoid going rich when your bigger secondaries kick in using an RPM-based adjustment. For instance, you couldn't install large secondaries and then just scale down the fuel map at some fixed RPM to compensate. There is no way to get the transition right since the secondaries come on at different RPMs based on the various conditions you listed.

The S-AFC adjusts fuel delivery by fiddling with the boost sensor signal to the stock ECU. Want more fuel? Tell the ECU that we are running higher boost than we really are. Want less fuel? Tell the ECU we are running less boost than we really are. The problem with this approach on the FD is that you will quickly run into the boost-related fuel cut (built in to the stock ECU) if you want to richen the mixture or run run a little higher boost than stock. You can't fix this with an FCD, because then the S-AFC wouldn't be able to tell the stock ECU to deliver more fuel.

The S-AFC seems to have a loyal following for some other cars or models, but it just doesn't work well on the FD.

If you want to run more boost but don't have a lot of money to spend, get a re-chipped ECU or a PFS PMC (AKA EFI PMS) used. I think there are many of them available in the used market. However, if you plan to mod the car out a lot, it may be worth saving up and getting a PowerFC (or another stand-alone) from the start. You'll spend less in the long run.

Also, my car was much smoother the moment I installed the PowerFC (no more 3K RPM hesitation!) and I think others have had similar experiences. If you have the 3K hesitation, get a PowerFC and it will be gone.

-Max