SAFC tuning on a 1g n/t

[codym]

I have had my car running for a few days now & I've gotten the chance to mess around with the safc a little bit. A friend of mine that has tuned quite a few dsm's ordered my safc for me, & he set the baseline tune for me leaving the shop where we were rebuilding it at. He mentioned that it would be set up for a 1g turbo maf so keep this in mind....

Being this is my first time tuning with one, I did quite a bit of reading on how it works so I'd have a better understanding of what was happening when I changed settings on the SAFC.

Now, currently on the 1g I have a stock 6bolt swap (still all motor for now) & fuel is still stock (240cc for 1g n/t) but I have some 450's I'll wire in afer I get the tuning down since it will require a little bit more precision to get the ratios just right.

Leaving the shop the baseline tune was set up to +3 low & high throttle. After driving down the street, I noticed it was real boggy, I did steady 30% throttle pulls & especially in the 2500-4500k range it would drive as it was hitting extremely rich.

I looked at some notes I had written on some general tuning information I had looked up and I got to thinking, if the safc is set up for a turbo maf, wouldn't it be sending the signal like it was on turbo injectors (450s) trying to make them run way over their duty cycle?
I wasn't sure if I was thinking correctly, so I added +1% across the board every few minutes & watched the idle. As I got close to + 7 as a baseline for Hi and Low throttle the Idle became very erratic, dropping sometimes close to 300 then back up to 8-900.

If I was thinking correctly, than I needed less fuel. So I dropped down to 0 for baseline & let it idle. Took a low throttle cruise - still boggy in the same RPM range. Dropped down to -3 across the board, idle, low throttle cruise- this time smooth rev up to 3000 then hit like it was still rich. Took it down some more to -8 and smooth rev to 4000.


Looking back at the notes which included some great info on how much fuel to add/take out using the safc for different injector sizes, I set it to -15 baseline to compensate for the 190cc difference in injectors. It still was a bit choppy here and there so I took it to -18 baseline for Hi & Low throttle. Idle was smooth as butter, drove to 5k with no lag or kicking at all. I did 2 WOT pulls in 3rd and 4th gear to get Hi throttle dialed in, set Hi at -17 overall and low at -18.

I didn't do any fine tuning because I still have to get a wideband & a logger, but I will be doing it soon. Let me know what you guys think, any input is welcomed.

 

[Cdc1221]

A 1g turbo maf is no different. It still sends the same signal. You really can't tune with the safc because there is nothing to tune being its completely stock. Now if you had something with a little more control, say link for instance, you could play around a little raising/lowering timing and fuel ratios to suit your needs. And to do any real good, you need a wideband for open loop tuning

 

[ColtiXim]

If you use 450cc injectors from a turbo model you need also a resistor box, they are low impedance.

Have you installed this resistor box ?

 

[YanDsm]

Sorry to tell you this but the best thing you can do with a safc is to put it in the thrash can. From experience, the safc just lie to your ecu about the airflow signal to make the engine running rich or lean. If you really want to tune your car for better performance, you need an engine management like ECMLINK, with link, you can play with afr and timing like cdc1221 said and you can get better performance. I've tried the safc too few years back and the better thing I did with it is to sell it to someone else.

 

[gusu]

The SAFC was from a time when any engine management was extremely unaffordable.

Even back then it's only use was to be a cheap ass and make a bit more power than stock by being able to deliver more fuel to the engine.

All you are doing with it is setting the ratio you want the SAFC to trick the ECU into thinking it's seeing.

So say you are running 15% larger injectors, the SAFC would lower the ratio of fuel the ECU sees by 15% to compensate for the ECU.

The reason why no one runs a SAFC if they can afford link, AEM standalone, Megasquirt, etc is simple. You can't actually do any real tuning with it like adjusting fuel trims and changing timing. Real tuning software also comes with awesome features like the ability to change your rev limit, turn off engine codes, actively log in real time or save logs, launch control, ISC emulation so you can actually delete it with out needing one physically on the car (You'd obviously need a delete plate), and many more options.




To answer your question as for dialing in the SAFC, I wouldn't even bother if you don't have a wideband or at the very least a EGR.

 

[codym]

Thanks for all feedback guys. I have a set of 450s on the side I was goin to put in, & yes I'm aware that you have to wire in the resistor box due to them being low impedance.

I traded a timing cover for the safc (awkward deal) so I didn't really go out of my way to get it.

I've done quite a bit of research on the variety of tuning options we have for our cars now, & as you all know link is probably leading the pack in that area and I do have plans to get link, but it requires more to run (wideband, gauges, etc )

One of the obstacles I was having is my ecu is EPROM , but it doesn't have a knock board. James, the friend of mine who has tuned many cars, imports and domestics alike, said that wouldn't be an issue as long as I'm all motor because I don't need a knock sensor.

I'll be posting in this thread as my tuning adventure continues, but it's original purpose was to get some feedback on if I was thinking correctly to set those values I mentioned earlier.

& gusu if you don't mind me asking what does the egr have to do with the safc ? Mine is blocked off.

 

[Cdc1221]

I think he meant egt probe, but that is unreliable at best until you get afrs and timing close to perfect, then you can tune for lower exhaust gas temps

 

[Mischif]

A safc on a non turbo is pretty much useless. zero everything on the the fuel adjustments for it. This will pretty much make it act like its not there.

Now with that said, i had a safc on mine when i was still non turbo. No matter how much i tweaked it, it never made a difference in performance. Also your o2 sensor is going to control things most of the time, so no matter what you do to the low settings on the safc they will not effect anything. The safc is only really useful for WOT adjustments. I had my non turbo running 450's with the resistor wired in and used the high setting on the safc to get my WOT a/f ratios in order. There is nothing to be gained from this, except verifying that you installed the resistor right and everything is working accordingly. I still use my safc to tune with now that im turbo, and i wont hesitate to say it is a very poor way to tune.

If i were you i wouldn't even play around with the safc settings if you don't have a wideband.

 

[codym]

When I zeroed everything out idle became very irrattic , also 30% throttle pulls were very laggy across the entire rpm range, no hi throttle pulls were made - I'm not exactly sure why my buddy would say the safc is set up for a turbo MAF if there is no difference between the two.
He has been working around safc's for quite some time now so I'm pretty confident he knows what he's talking about.

The logic I used to set the fuel trims seemed to work well for me , idle is clean, low and hi throttle pulls were smooth. Wideband is on the way & after I get it installed I'll post up my findings.
Keep the feedback coming !