NZ_87_TURBO

I put this in the EMS forum also but as its a graveyard it probably wont get answered.

Hi,
Im about to install my SAFC on my 87 T2 which is currently running a HKS PFC FCON. The wiring diagram from the apexi site tells me that i wire the yellow and white wire into the pressure sensor signal to the FCON from its own MAP Sensor.
I have also read about people using a MAP sensor for there throttle input (gray wire) when using a SAFC as it is more accurate.
Can i just take same input (MAP ) signal that I would wire the white wire to for the throttle signal?

Another question that is not really related is. How many feeds can i tap into the ECU ignition power source?
Im thinking of running a thick wire with some sort of plug/adaptor on the end that is gona sit in behind the stereo compartment that I can wire electronics into that require a 12v ignition source. ive got need for a feed for my SAFC,AFR Gauge, Boost controller, CD player

I am also looking at bringing a RPM signal from the ecu to a similar accessible position for use when i use a wide band and wish to data log against rpm

arghx

iTrader: (3)

I don't know much about the F-CON. Is that just a chipped piggyback thing? Does it allow you to remove the AFM or something?

Either way, I am looking at the wiring diagram for it right now. On a stock ECU the SAFC alters the signal from the AFM to the ECU, so you cut the AFM wire. The input side (harness side of the AFM wire) connects to the White wire of the SAFC harness, while the yellow wire connects to the ECU/connector side of the wire you just cut.

In similar fashion you are cutting the blue pressure sensor wire to the F-CON. The pressure sensor side of the blue wire connects to the white wire of the SAFC harness, while the FCON side of the blue wire connects to the yellow wire of the SAFC harness. You seem to understand this.

Throttle position should be a fixed input, so do you think it makes sense to get input data from a signal wire that the SAFC will be actively altering? I guess if you did it, you would want to tap the signal from the pressure sensor side of the blue wire (what you normally connect the white wire to). It just doesn't seem like a good idea to me though.

So that leaves you with the stock TPS signal or the stock pressure sensor signal (you do keep the stock pressure sensor with an FCON right?). Between those two, I think it doesn't matter. It won't make much difference unless your TPS is completely messed up. An SAFC is useless under anything less than WOT in my opinion. Usually at part throttle the car is in closed loop and it will ignore AFM correction. I guess sometimes when you are boosting at half throttle the car will go open loop and then AFM correction might help, but overall it doesn't make much of a difference until you are dropping the hammer.

An SAFC cannot alter acceleration enrichments either (extra fuel added in as the throttle plates open, determined in part by the TPS)--you need a standalone for that.

So to summarize: hook it up like in the diagram, and then hook the throttle input to either the TPS or the stock pressure sensor, but it won't make a big difference either way. Oh and you can get a tach signal from the trailing coil, you don't need to go to the ECU. On the subject of the ignition harness, it's all going to depend on how much amperage you are going to pull. That's gotta be maybe a 14 gauge wire so it could probably handle a decent amount more current before probably blowing a fuse.

gsracer

I know this has been posted numerous times in the past several years. The advantage of using the MAP sensor instead of the TPS sensor is that the switch between high and low maps on the safc is triggered by pressure and not throttle position. I could be in deep vacuum or boost at the same throttle position...

Both the MAP sensor and the TPS sensor are 0-5 volts. The MAP sensor is a standard 2 bar sensor. The equation correlating voltage output with boost pressure is floating around somewhere on this forum, use the search function.

arghx

iTrader: (3)

Well, I guess if you did it exactly right you could get some more tuneability by using the pressure sensor...

NZ_87_TURBO

IIt sure has and i read a 7 page thread in which you featured many times although i still arnt 100% sure about setting the throttle reading to suit the pressure sensor, there was a few posts which said you had to use the TPS first then swap it over coz they are both 0-5v outputs ( very confusing )


I wanted to know if i could use the FCON pressure sensor? is that 0-5 volts and does any one know if its a 2 bar sensor or more?

I could use the 3 bar MAP i have for my EVC 4 ?

NZConvertible

It depends on the total electrical load, not the quantity. Most electronic boxes (like the S-AFC and the ECU) have very low power consumption. The wire feeding the ECU will probably be more than big enough for a few extras, and the fuse protecting it (30A EGI COMP) probably has a lot of spare capacity on it. If you've removed the solenoid rack it's only providing power to the fuel pump resistor relay, power steering relay, air supply valve, BAC valve, atmospheric pressure sensor, MAP sensor and knock control unit. All low-current items except maybe the BAC valve.

Again these are all low-current items so you should be fine coming off a wire coming from (not to) the fuse box.

ECU pin 1X or the trailing coil diagnostic connector, your choice. Taking it from the ECU avoids pulling yet another wire into the engine bay.

https://www.rx7club.com/attachment.p...hmentid=165722

Are you sure you want to go on record as saying that throttle position is a fixed input. As in the throttle position doesn't change. The throttle never moves. There's a position sensor on a fixed item. Sure...?

Actually on an S4 it makes a huge difference because there's only a narrow-band sensor to get a throttle position signal from. Using the TPS signal gives a 100% throttle reading at 1/4-throttle, which limits your scope for tuning.