S-AFC II - Used to display boost for FC?
 

My NA Supercharging project is almost complete. I have a gauge pod for my ashtray that will hold both a digital Intake Air Temp and a Water Temp gauge. I don't want any more gauges if possible, but I would like to monitor my boost levels to see if the belt is slipping.

I was looking through the manual for the S-AFC II and noticed that they have a Pressure display function. It seems like this can display boost levels on the S-AFC II; however, I'm not sure if there needs to be some kind of exisiting sensor in the car that the S-AFC reads the boost from.

Does anyone have any info on this?

If you care to see the manual, you can download it from this link:

http://www.apexi-usa.com/productdocu...-AFC2Final.pdf

im not too familiar with the S-AFC as its more of something i see on hondas (that might be a burn, im not sure)
but i can guaruntee that you will need a boost sensor to read boost-S-AFC or not

Just go with a separate boost gauge. Even with a pressure sensor, unless the SAFC is in pressure sensor mode (used on, say, FDs), you won't see anything except the raw voltages.

If you have more questions, ask. I've gotten to know my SAFC quite well as of late.

-=Russ=-

I have the safc2 and it does not read boost. it is a tool specifically for monitoring and adjusting fuel. You can AFM,correction, knock, throttle , but no boost. you will have to have a boost gauge

Ok. In reading that thread, it seems like it's definitely possible. However, the pictures are dead. It seems like this sentence sums it up, right?

This is how to make the S-AFC II read boost on a 90 NA Vert?

BTW: My S-AFC II is already installed and working fine when the car was NA. I just want to use it to also display boost pressure.

Not possible. The pressure option is for a car that uses a pressure sensor as it's primary fuel input, like the FD. Since you're using it on a car with an airflow meter, no dice.

If you wanna get tricksy, get a TII instrument cluster with the boost gauge in place of the voltmeter. Get a TII boost sensor and feed the output to the boost gauge - good to go, and it's clean.

PM me if you have any other questions - I've done quite a bit with the S-AFC.

Dale

Dale,

In the thread referenced above, is Jason (NZConvertible) disagreeing with you, or am I just reading it wrong? I don't want the S-AFC to react based on boost pressure; however, I would just like to use it as a boost gauge. My car still has a MAP sensor, right? Sorry if I seem dense, but I'm just trying to resolve the discrepancy in my mind.

For purposes of this paragraph, let's just say the NA does not have the proper sensor. How difficult would it be to add this sensor to my NA and use it SOLELY for purposes of obtaining a boost pressure signal that the S-AFC II can interpret?

Alan

Alan

OK, read that post - that's some confusing stuff there :).

First off, I pioneered the trick AGES ago of using the stock FC pressure sensor as the TPS input. The S4 TPS reads full open at about 25% throttle, which is useless for tuning. You can tap into the boost sensor instead with the throttle wire from the S-AFC (they're both 0-5v outputs) and set the lo/hi throttle points as lo/hi *boost*, not throttle. Since you have an '89-91 FC, you do have a wide-range TPS output - you can use either.

Anyhow, when you set up the S-AFC you set what type of airflow meter you have and which one. Your car has the FL (Flap) type. With that set, you CAN NOT read or do anything with pressure. You have to have a PR (Pressure) type airflow meter input to log or view pressure. I have NO idea why that guy has a pic of the car with the Pressure input on the screen - he would have had to set the AFM type as pressure to get that, plain and simple.

The blue wire on the S-AFC is for a second airflow meter - the Skyline GTR has 2 hotwire airflow meters. Many people tap that wire into another input, but you can only read that input at the "sensor check" screen. Originally some DSM guys were tapping the blue wire to the O2 sensor to read O2 voltage to tune with - unfortunately, the blue wire loads the O2 circuit giving you a false reading. Anyhow, if you set the S-AFC to Flap, that locks out the blue wire's input for anything useful.

The NA's have boost sensors - the reason being is it's the input to the ECU for timing. Old distributors typically have a vacuum advance - that's why you have the pressure sensor, for the ECU to set timing with. The NA boost sensor, I believe, does read *some* boost, but the turbo boost sensor has a different range and reads more boost.

Hope that makes sense. Unfortunately, a lot of the information on the S-AFC is REALLY off or wrong. I've messed with a pile of various Japanese car electronics, so I'm pretty handy with these doo dads :). My old FC was a poster child for 3-letter Japanese doodads at one point :).

Dale

OK, now I read through that thread again and I may be wrong. It does seem like he hooked the blue wire up to the stock boost sensor and got a reading - I don't think it's possible, though. Might be worth experimenting with, or PM'ing that guy (SureShot). It just doesn't make sense with what I know about the S-AFC, though.

Dale

Did you ever try to get it to work? Did it read anything?

HOPEFULLY, next week it will get finished and we will be able to try it.

The S-AFC manual does imply that it will not work.
As you can see in the picture, it does happen to work on mine.
This could vary from one software version to another.

After some experimenting, I liked your Idea about using the pressure signal.
I currently have the gray wire tapped in from the presssure sensor on my S5.
In cold air, the boost can get ahead of the throttle.
This keeps the fuel correction from getting behind.
I found that 0 PSI shows ~40% and 12 PSI shows 90%.
I set the THR settings at those values so it stays in the low map all the time while crusing.

The blue wire wire is tapped in at the ECU and shows the FCD clip.

Hey I know this thread is really old now but I never did see if you got this to work. I was looking through my old posts and saw that this thread was still hanging.