projectxspeed
Senior Member
Which would better for basic Air/Fuel tuning on my b18b. A vfac or sfac?
Looking for a basic tuning option
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projectxspeed
Senior Member
I knew that 
thats for the spelling help. Beside vtec is there any difference between the too
thats for the spelling help. Beside vtec is there any difference between the tooprojectxspeed
Senior Member
Well that kinda of negative 
, care to explain?
, care to explain?
allbottledup
Senior Member
I had a VAFC in my b18b..it came with the car. well anyway I tuned it like it said too from a previous post on this sight. The post said that you give it more fuel with the tourqe curve. Well I did that never got a chance to dyno it but I didnt feel too much of a difference. I just tuned it and looked at my air fuel guage. Granted like i said its not the right way to do it, but i did what i could. I ended up selling it and decided it would just be better to get a hondata ecu. Didnt get it yet but I will soon. Hope that helps.
projectxspeed
Senior Member
Thanks for the input, with the vafc you can adjust the vtec engagement point right?
allbottledup
Senior Member
Yeah theres alot of tuning options that didnt pertain to me. So at the time I could use the extra money. Got 225 shipped for it on ebay. Like i said it would be worth it to save up for a hondata.
or check out www.pgmfi.org and look into self-tuning....
projectxspeed
Senior Member
Ya you are definitely right but I might be able to get one off a friend for 100 so a nice band-aid til I get the good stuff
As I do not have a SAFC, I can only tell you about what the VAFC does.
It will allow you to set your VTEC engagement point. You can also set the fuel compensation for when you switch to the vtec lobe on the cam.
It will also allow you to make fuel corrections (+/-) anywhere in the RPM range. You have the ability to set your narrow/wide throttle positions. With those, you can also set your HI/LO cam profiles. So you basically have 4 positions you can tune at: Narrow/Lo, Narrow/Hi, Wide/Lo, Wide/Hi. I know that sounds really complicated at this point, but if you ever had some time in front of one you would understand it better.
Aside from the tuning, you also have 6 different things you can monitor. Intake pressure, throttle position, rpms, vteci (the incoming vtec signal to the ecu on/off), vteco (the outgoing vtec signal to the solenoid on/off), and correction (% fuel correction).
It will allow you to view up to 4 of these options at the same time in 3 different views. You can view them numerically, in graphical form (and record up to 20 seconds w/ playback), and you can view them as gauges (only 2).
It's actually not a bad toy if you ask me. Are there better options out there, sure. Is it worth the MSRP? I'd have to say hell no. I picked mine up off ebay 2 years ago for $200. Hope the info helped.
It will allow you to set your VTEC engagement point. You can also set the fuel compensation for when you switch to the vtec lobe on the cam.
It will also allow you to make fuel corrections (+/-) anywhere in the RPM range. You have the ability to set your narrow/wide throttle positions. With those, you can also set your HI/LO cam profiles. So you basically have 4 positions you can tune at: Narrow/Lo, Narrow/Hi, Wide/Lo, Wide/Hi. I know that sounds really complicated at this point, but if you ever had some time in front of one you would understand it better.
Aside from the tuning, you also have 6 different things you can monitor. Intake pressure, throttle position, rpms, vteci (the incoming vtec signal to the ecu on/off), vteco (the outgoing vtec signal to the solenoid on/off), and correction (% fuel correction).
It will allow you to view up to 4 of these options at the same time in 3 different views. You can view them numerically, in graphical form (and record up to 20 seconds w/ playback), and you can view them as gauges (only 2).
It's actually not a bad toy if you ask me. Are there better options out there, sure. Is it worth the MSRP? I'd have to say hell no. I picked mine up off ebay 2 years ago for $200. Hope the info helped.
allbottledup
Senior Member
If you can pick it up for 100 go for it cause you can easily sell it for more than that when you want to upgrade to something better.
for 85 bucks you can get a ROM burner from www.moates.net and some EEPROMs then some resistors and sockets real cheap and tune your ECU with crome, uberdata etc.
I should make an entry in the Wiki on PGMFI so I don't have to keep typing this.
I have beef with VAFCs, SAFCs, and piggybacks in general.
VAFCs and SAFCs work by fiddling with the MAP sensor voltage. The MAP sensor is what the ECU uses to tell how much air is going into the motor. When you "richen" the mixture with the VAFC, you are simply increasing the MAP voltage at that point. When you "lean" the mixture with the VAFC, you are simply decreasing the MAP voltage.
Why does this make a VAFC/SAFC a poor tuning solution? When you change the MAP signal you are altering both TIMING and FUEL. Anytime you "lean" the car out, you advance the timing too. Anytime you "richen" the car, you retard the timing too. This is the main reason why people who run the "AFC hack" for boost have trouble with ignition timing - with a 40% "lean" setting, timing can get jacked up 10-20 degrees.
I have beef with VAFCs, SAFCs, and piggybacks in general.
VAFCs and SAFCs work by fiddling with the MAP sensor voltage. The MAP sensor is what the ECU uses to tell how much air is going into the motor. When you "richen" the mixture with the VAFC, you are simply increasing the MAP voltage at that point. When you "lean" the mixture with the VAFC, you are simply decreasing the MAP voltage.
Why does this make a VAFC/SAFC a poor tuning solution? When you change the MAP signal you are altering both TIMING and FUEL. Anytime you "lean" the car out, you advance the timing too. Anytime you "richen" the car, you retard the timing too. This is the main reason why people who run the "AFC hack" for boost have trouble with ignition timing - with a 40% "lean" setting, timing can get jacked up 10-20 degrees.
That's very true... VAFC/SAFC don't give you control over timing tables. I'll post up proof of why this is so important later on today... dyno charts for evidence too.
VAFC vs SAFC:
The VAFC will work just as well as an SAFC in any Honda application. The main functional difference between the SAFC and VAFC is the ability for VTEC control. The important difference between the two is that the VAFC is set up to really only work with Honda sensors, while the SAFC can be configured to run with many different types of cars. You can run the SAFC on pretty much anything- Nissans, Mazdas, Toyotas etc- but I'm pretty sure that the VAFC will only work on Hondas and cars with sensors that work the same way.
The VAFC will work on any non-VTEC Honda the same as an SAFC would. If you decide to go the piggyback route and don't have to trim in a significantly modified setup, you'll probably be ok. If you have the willingness to burn chips and play with full custom maps with some more cash for dyno and wideband time, get a programmable solution like Hondata or Uberdata.