I'm looking for a good FMU. I know the cartech 2025 is recommended for turbo applications but I was also looking for Apexi SAFC-II.
What you guys recommend for FMU ?
Will I need any other part to install the Apexi SAFC-II ? Is it hard to install and tune?
I bought the AEM UEGO wideband.
Thanks!
Get the Cartech fmu if you need to choose between the two. The Cartech is boost dependent. It will increase fuel pressure by reading boost. The S-AFC is rpm dependent. It increases the injector duty cycle by reading the rpms.
This is what happened when turbo 2.2 was tuned with only a S-AFC. The car was tuned for 6psi on the dyno with the S-AFC. When the owner picked up the car and was driving home, the car was hitting 10ps on the street....boom
275hp & 306tq - 1999 2.2 ohv
13.2 @ 108 mph
-1996 2.4 liter + Turbo + Built motor + Torco + More boost = Lots o' Power
-2000 Mustang GT + 2004 Cobra motor, Whipple 2.3 supercharger,
built rear-end,Dodge Viper spec T56 6 speed, bolt-ons = wheelies at the track!!!!!
@!#$ed is on business right now so he couldnt post and he asked me to post this.......
Adler wrote:Get the Cartech fmu if you need to choose between the two. The Cartech is boost dependent. It will increase fuel pressure by reading boost. The S-AFC is rpm dependent. It increases the injector duty cycle by reading the rpms.
This is what happened when turbo 2.2 was tuned with only a S-AFC. The car was tuned for 6psi on the dyno with the S-AFC. When the owner picked up the car and was driving home, the car was hitting 10ps on the street....boom
Thats not how it works
The SAFC modifies the MAP sensor signal (notice how its spliced in between the MAP sensor and ECU?). It increases the signal to make the ECU think that more air is going in to the engine than there really is. Here's the problems though (and I recently found out one after I got the HP Tuners software)
1. MAP sensor maxes out at 0 PSI (atmospheric). The SAFC cannot make the ECU think more air is going in than you would have at WOT on a naturally aspirated engine, which is not enough for boost by far.
2. The VE table, the one that tells the ECU how much air is going into the engine, is NOT based on the map sensor (I can show you screen shots proving this). It is based on the RPM and the TPS sensor. That means the only thing the SAFC is doing is making the timing retard (since the only MAP based table on an N/A ECU is the High/Low octane spark tables).
So, the SAFC is useless for boost, get an FMU.
So if I understand, there is no advantage for me to have the SAFC because i'll do the s/c reflash.
Thanks! I'll go with catech.
There are advantages, but an FMU is needed, I use them both, I use an FMU for under boost and the SAFC to tune my injectors being that their rather large for anything not WOT, you can use an AFPR regulator also to do this however, but i find it nice to be able to fine tune by rpm to get the A/F just right across the board. You just have to tune around the FMU, since it kicks up under boost you have to tune the SAFC to be in high throttle when your under boost and set a different table for it then normal driving where the FMU isnt kicking 60psi of backpressure in the fuel rail.
So some people are using a fmu and safc... did I understand that right.
So, the SAFC is useless for boost, get an FMU.
I disagree here.......The SAFC has its uses......but it cannot be used as the only fuel tuning tool.
The SAFC should by no means be substituted for a FMU. But when you are driving a Cavalier with no headwork while running 440's, you can use that extra control over your fuel while you are not in boost. Unless you like smelling like you live in a gas station.
Also, while in boost I had to PULL fuel to get decent A/F ratios. Otherwise I would bog down at about 6-7psi under hard acceleration. At 9-10psi my fuel was fine, but up to that point I was way to rich for some reason. The SAFC tool allowed me to "fix" this. Somewhat......
Boosted Eco @9psi for now....WRX come spring.....
the SAFC alone cannot adjust for additional air, it is to tune the map voltage to adjust for larger injectors and alike on a NA engine. Once the computer sees 4.9v (or whatever) that is maxed out, the SAFC cannot increase that to 6.0V to add more fuel with boost.
That being said it is possible to put in larger injectors and tune them down at idle, and increase duty cycle as pressure builds. but then you are adding the same fuel at 1psi boost as 10psi... therefore running really lean.
Having said that
Quote:
2. The VE table, the one that tells the ECU how much air is going into the engine, is NOT based on the map sensor (I can show you screen shots proving this). It is based on the RPM and the TPS sensor.
it really doesn't matter what you do with the SAFC to the MAP signal, becuase it is not being used in the calculation.
with a Begi 2025, it adds fuel according to boost (hense the 8:1, 6:1 or fully adjustable to whatever you want) so if you tune it right at 6psi, as long as you don't clip your injectors with 12:1 or something they are really good for low boost applications.
You are going to run something with the GM s/c reflash, (I am too), and I have the 2025, and will likely have it set really low 3:1 or 4:1, I will use my AEM wideband to adjust from there, just so I can get to the dyno and tune it better.
Shifted will have more info about tuning *fingers crossed*, so once they support the GM s/c reflash, I will ditch the FMU, and tune it with a computer.
HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED
