Alright heres the deal. I have 75% of the install done. For now till I get the MS, which is very soon, Im runnin on stock injectors. I have a SFMU. Can I run the car on just the SFMU till I get the MS or do I need the SAFC? I am moving up to 450cc's once I get the MS.

Sfmu and stock injectors are FINE. SAFC will increase timing=boom engine bye bye. MmmKaY.

Got it.

Thanx man

The problem is people are not using the SAFC safely on our cars. If you use the SFMU for the majority of the contrl and use the SAFC for fine tuning then you are fine.

When i discussed this with Lee (Mr slick) he was runnign 450 dsm injectors with a SFMU with 20psi idle. the SAFC was at -10% 1000rpms and +/- 4% throughout the RPm range. This is how i had mine set up and it was fine except for my damn CEL. This will not alter your timing to the point it is noticable. People are thinking they can just make all the corrections with the SAFC and no problems will occur and of course everyone who ready the results just parrot how bad it can be without knowing how or why.

Terry
96 Eagle Talon ESI....Daily driver

97 Eclipse.........

Originally posted by Star Turbo Talon
and of course everyone who ready the results just parrot how bad it can be without knowing how or why.

right now i run with a SFMU, wideband 02, and SAFC. its tuned to perfection and timing advance is a lot perkier at low throttle.

people just need to learn how to tune with it, thats all

The S-AFC alone does not advance timing. Reducing MAP voltage with the S-AFC out advances timing. Increacing MAP voltage with the S-AFC retards timing, but you can't increace the voltage too high or you will hit the level of the fuel cut defender, or, if you don't have one, you will get fuel cut.

One intersting thing I learned a while back was that the engine has a higher fuel demand for fuel around peak volumeteric efficiency (almost always very close to the point of peak torque). When you start messing around with things like changing the cams or adding a turbo the torque curve will change from that which the factory open-loop injector pulsewidth curve was designed for. The S-FMU just rises pressure to the injectors, it doesn't care what the RPM is. All it knows about is pressure. The ECU is pulsing the injectors thinking that you still have the factory airbox on.

When I dyno'ed back in March of 2003, I had the S16G, a S-FMU, and a set of 415 cc/min injectors. I did not really know how to tune back then, I was too afraid to mess with the S-AFC because I thought I would blow my engine by having timing that was too far advanced, I used it only to make the car idle a little better. I have still yet to hear about someone who has destroyed their engine from using an S-AFC alone.

Anyways, I'd always get a really lean spot (like 13.0:1) right around peak torque, back then it was around 3500-4000 RPM's, but it would magically richen up as you went above and below this in the powerband. This is where the S-AFC comes in with a S-FMU fuel setup... You richen up the S-FMU so it's perfect right where peak torque is (this will make it insanely rich higher up in the powerband, like at redline), and where it's out of peak torque, you lower the MAP voltage that the ECU sees using the S-AFC (make the correction negative at that RPM). Remember, detonation is less likely to happen at higher RPM's, and the few degrees of advance would certinly be helpful to continue to make power outside of peak torque.

very good info ner, ive noticed that too....the lower rpm's as well as the higher rpm's (6-7000) are leaned out, and right around peak torque demands the most fuel

personally, i love the way my car runs tuned with an SAFC....the boost builds up damn fast because of the better spool time, and it rips hard all the way to redline

in my honest opinion....mate an SFMU with a datalogger and SAFC and a wideband and you have some serious tuning tools to go to work with

True. If you know how to tune, a S-FMU and an S-AFC is better than a poorly tuned 8 injector setup, and in some cases, it can be almost as good as a well tuned 8 injector setup.

Well this will only be for a short time. I already paid for the MS and once MR.SLICK is done building it, Im going over to his place to get it running. So I guess I can run on just the SFMU for like a week ot two, right?

Yeah, you'll be fine. Just leave in the biggest S-FMU disk in there for now, pull off the vacuum line while the car is running and set the fuel pressure to 45-50 psi.

Once you get the 450's and the MS, it would be best to get an 1:1 Aeromotive or equivelent, or you may be able to get away with sticking in the smallest disk in the S-FMU. See what works out.

By the way... If you don't like how your 450's work out, I have a set of cleaned 450's if you'd like them. Flow sheet and all, I never installed them.

Now wait a minute. I was told for now, to run the 2.72 disc in the SFMU, with the dark spring, with the vac line hooked up. Now which should I do, 2.72 disc with the vac line or the biggest disc with no vac line? I just need a solid answer to go by when I start this motor up.

I did get my 1:1 FPR today, so I wont need the SFMU when the MS is ready.

If you are going to run stock injectors, with the S-FMU, you will definately want the largest disk. This is the one that doesn't have a ring, and it's the one that comes pre-installed when you buy the S-FMU brand new.

If you are going to be running 400-450's with a S-FMU, and the stock computer, you will want the 2.72" disk.

The spring choice and the vacuum restrictor is usually up to the end user. Most people like the stiffer/dark spring, but some use the standard silver one.

EDIT: For the vacuum line thing, that's only if you are running the stock injectors with NO turbo, or when you are tuning the static pressure WITH a turbo. If you are running boost, you will want the vacuum line hooked up.

Loud and clear. Thanx again man!