WJM Posted December 9, 2004 Share Posted December 9, 2004 So...what wire send the voltage for the ECU to know when to fuel cut? what wires to I need to splice in the Super AFC for? Quote Link to comment Share on other sites More sharing options...
Subarutex Posted December 9, 2004 Share Posted December 9, 2004 MAF signal wire for the SAFC. I would put the FCD on the MAF signal wire too, but between the SAFC and the ECU. MAF -> SAFC -> FCD -> ECU. Keep in mind that the SAFC should be hooked up damn close to the ecu. Quote Link to comment Share on other sites More sharing options...
WJM Posted December 9, 2004 Author Share Posted December 9, 2004 but wont the SAFC and FDC negate each other? FDC clampl voltage...and SAFC add that voltage right back to it? Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted December 9, 2004 Share Posted December 9, 2004 Tex... get on AOL IM so we can talk -Brian Quote Link to comment Share on other sites More sharing options...
Do It Sidewayz Posted December 9, 2004 Share Posted December 9, 2004 man...unless your getting the SAFC for free.. or already have it...It's not worth your trouble. it simply doesn't do enough to warrant using it. Quote Link to comment Share on other sites More sharing options...
Subarutex Posted December 9, 2004 Share Posted December 9, 2004 I had some good success with it. WJM. Go through my schematic again. MAF -> SAFC -> FCD -> ECU. Thus, the SAFC gets the original signal from the MAF and modifies it per the programming you've done. Next, the FCD gets to look at the MODIFIED MAF signal coming from the SAFC. This way, if the SAFC modifies the MAF voltage past teh cutoff point, you are still safe. I had massive problems with the SAFC modifing the voltage past fuel cut. Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted December 9, 2004 Share Posted December 9, 2004 M-I-C.... K-E-Y... M-O-U-S-E!!! Anyone care to explain what a SAFC is? How about a FCD?? -Brian Quote Link to comment Share on other sites More sharing options...
Do It Sidewayz Posted December 9, 2004 Share Posted December 9, 2004 SAFC is a product made by Apexi . although there are many different products which do the same thing. it is a "piggyback" computer which allows you to "hack" the MAF or MAP sensor signal which goes into the computer. This makes the computer think that there is more or less air going into the engine. By doing this the computer add (or subtracts) more fuel and often times timing. The problem with the SAFC is it can only do so much, as it only modifies one sensor input. FCD is "Fuel Cut Defender". You know..what happens when you pull too much boost in your 87+ EA82T car. Basically when the MAF senses that you are pulling enough air though the air flow meter to make 13 PSI (i think) The MAF puts out a voltage of something more than 4.7 Volts. Once the computer senses this for more than 3 Seconds, it will Cut Fuel. Basically. The computer will first try and open the wastegate with the Boost Solenoid, Since the computer senses that at 13 PSI your wastegate is stuck closed. However if you have an MBC/EBC (boost controller), you usually don't have this soleniod hooked up...or you are experiencing "boost creep" (wastegate is fully open but the exhaust is easier to flow through the turbine as it is the path of least resistance). All an FCD is, is basically a Voltage Regulator. It never lets the Computer see more than 4.7 Volts (or whatever which is boost cut). Now......FCD's cost a couple hundred bucks from manufactures. In reality, you can use a 10 cent part. A simple 4.7 or 4.3 Volt Zener diode will do exactly the same thing. And the SAFC....i really want to see someone use the same Piggyback system i have in my Justy. I'm running the Greddy Emanage. The emanage is a "piggyback" but is MUCH more adjustable. It does what the SAFC will do.....but when you plug it into your laptop, the choices are endless. with the emanage you can do this: -add injector duty cycle for more fuel -add a correction factor for larger than factory injectors -modify MAP/MAF sensor voltages -Add/Pull timing -correction for a atmospheric BOV -Built in Fuel Cut Defender -Datalog all connected sensors, and your changes -has an extra 0-5V input for logging/mapping (perfect for a wideband O2) all of these can be mapped with respect to RPM, Boost/Vac pressure, Wideband reading, TPS input....whatever I'll prolly regret saying this on here, because so many are dead set on the Megasquirt with fancy ignition stuff.....BUT The Emanage is probably a better set-up for these cars than the Megasquirt....Mainly because you don't have to mess with as many wires, you still have the factory base maps, you just add onto them. With an 87+ car where the computer already has controll of the timing, it's alot easier. On an 87- car...well ok. go with the ignition conversion...because the computer doesn't controll the timing. I'm running the system on my Justy which i Turboed. I have a VERY rough tune on the car right now (too rich), as i haven't been able to get any good pulls in because i can't keep the clutch from slipping. I'm probably making somewhere around 125 HP, it hands my 85 RX Turbo rally car it's rump roast on a platter fairly well...even with a slipping clutch Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted December 9, 2004 Share Posted December 9, 2004 Thanks... I just learned today about the fuel cut, and im kinda upset over the whole ordeal. From what ive learned the stock RX makes 6.5psi and the ecu will cut it at 9psi (after about 10seconds). I'd like to get around that. -Brian Quote Link to comment Share on other sites More sharing options...
Do It Sidewayz Posted December 9, 2004 Share Posted December 9, 2004 Well...that depends We have an RX that iwll pull 15 PSI all day long. Same with a 1987 XT Turbo. We've even seen as much at 22 PSI, with no fuel cut. Since the computer doesn't actually measure boost pressure in any way, instead it measures air flow. the Fuel cut is greatly dependant on air density. When it's cold, or when it's hot, you will see more or less boost. Quote Link to comment Share on other sites More sharing options...
Tachometer Posted December 9, 2004 Share Posted December 9, 2004 I remember back in the day when Sport Compact Car had their Project 2.5RS. They eventually turbocharged it and had a PILE of various piggyback computers keeping everything happy. I knew the guy who owned the car (he now runs Vishnu) and they had endless trouble trying to control everything with all those various computers. FCD, S-AFC, knockguard sensor, EDC, electronic boost controller, etc etc. Eventually they went with a TEC-II (funny...Shiv sells/sold those through Vishnu...hmmm!). It was an awesome machine that worked amazingly well. Now with the TEC-III you can tune even better. I've heard of that Greddy emanage and it sounds like a great solution for these kind of problems. A TEC-III would definitely be overkill...but mad could you do some wicked tuning. Great explanation Do It Sidewayz, that made total sense. That S-AFC is really popular for tuners probably 'cause it looks so cool but if air/fuel is your specific issue...then it is the perfect device. In some ways all this complicated electronic trickery makes me yearn for the days of carbs...but then I sober up Quote Link to comment Share on other sites More sharing options...
WJM Posted December 9, 2004 Author Share Posted December 9, 2004 and, once again....i go... Hmmmmmmmmm......... Quote Link to comment Share on other sites More sharing options...
Do It Sidewayz Posted December 9, 2004 Share Posted December 9, 2004 Yes...most people like the SAFC because it's blue, sits on the dash and goes bling. What they are good for is fine tuning, and subtracting fuel. In an application where you need to add fuel they do not work very well. In conjunction with a Rising Rate Fuel Pressure regulator or bigger injectors, they work decently well at subtracting fuel to a point. They are mostly used on N/A or near stock turbo cars, to try and maximize the factory fuel maps, as they are normally very rich from the factory to be safe. To subtract a little fuel and "lean it out" to get a few more ponies, it's ok. Or to maybe compensate for an intake and exhaust on a Honda...ok..you'll prolly make it. When you start running EA82T's at 14-15 PSI of boost, you realise you need more fuel. By the time you get something like an SAFC and a rising rate/injectors. you are looking at the same price (if not more) than a better management unit. Quote Link to comment Share on other sites More sharing options...
Myxalplyx Posted December 9, 2004 Share Posted December 9, 2004 Another thing about that SAFC. I was unsuccessful at installing it on one of my XT6s. Two important setting you need to figure out are: 1. Sensor Number and, 2. Sensor Calc... The Apexi SAFC handbook doesn't mention what exactly these numbers are for but it will tell you how to set these setting for what specific cars. If your car isn't on that list, you have to 'trial and error' the settings and hope you hit on the right one. It is risky! My trial and errors almost ended in a roasted engine. Apexi USA refused to help me if my car wasn't on that list. Apexi Japan may have been able to help but the rep there (talking in Japanese) stated that I needed to 'bring my car to them' so they could look at it and decide what setting was safe. Not! No matter what settings I put it on (I started with the Impreza settings), the car would go extremely lean on the top end and my EGTs (Exhaust Gas Temperature) would start to soar past 1600F. This was extremely dangerous as my car only ran around 1530F tops. It was running this lean even before I attempted to try nitrous (which actually cooled it a bit but it still was too lean). So I took it off. However, using a Hyper Fuel SFC (same function as SFC but is simpler with much less options), I was successful in my Outback Sport when it was turbocharged and running nitrous. I had no problem on stock fuel injectors, stock pump, stock internals (Totally not recommending anyone do this) for many, many miles. The car actually ran too rich at some settings but my EGTs were in happy-land throughout the abuse. I believe you can use these sucessfully in adding fuel although I've read most people had better success using it with fuel injectors that do not flow more than 50% over stock. The choice is yours and good luck! If you do install it, please post your Sensor Calc and Sensor Number settings. Thanks! Quote Link to comment Share on other sites More sharing options...
Caboobaroo Posted December 9, 2004 Share Posted December 9, 2004 and, once again....i go... Hmmmmmmmmm......... I think I'll join you on this one Will...... Hmmmmmmmmm......... Quote Link to comment Share on other sites More sharing options...
Subi81 Posted December 10, 2004 Share Posted December 10, 2004 Good post losts of info. I always wondered how the 87+ cars "sensed" an overboost situation without a pressure sensor. Quote Link to comment Share on other sites More sharing options...
Myxalplyx Posted December 11, 2004 Share Posted December 11, 2004 Hey guys, check out SubaruTex's response in this post: http://www.ultimatesubaru.org/forum/showthread.php?t=10204&highlight=fuel Apparently he used an SAFC on his Subaru and have had some success with it. It was installed and everything. I thought I sent out questions about the Sensor Calc and Sensor Number setting but maybe that was another board. Ask him how he had it setup and what did he think about it overall. Quote Link to comment Share on other sites More sharing options...
WJM Posted December 11, 2004 Author Share Posted December 11, 2004 Very good info shadow. Again, Im sticking with the MS+DIS route....i was considering alternatives...but there are NONE other than the MS+DIS. I will, however, keep the GReddy EBC i have when I do MS+DIS...I love it! Quote Link to comment Share on other sites More sharing options...
oddcomp Posted December 11, 2004 Share Posted December 11, 2004 shadow said what i was thinking of how to say no wonder i filter some of my info thru him lol there is actually one more besides ms not as cheap or userfriendly in my opinion but you see it mentioned on the turbododge forums a bit i think its called sems or something like it simple engine management or some such thing according to the guys who did it they looked at what ms could and couldn't do and they built that one.. but it costs much much more much much Quote Link to comment Share on other sites More sharing options...
WJM Posted December 11, 2004 Author Share Posted December 11, 2004 simple digital systems...? Quote Link to comment Share on other sites More sharing options...
WJM Posted December 12, 2004 Author Share Posted December 12, 2004 Oh yeah, i remember reading that part on the lap top....but....there is a reason why ia m choosing MS over it...i just dont remember why. Quote Link to comment Share on other sites More sharing options...
WJM Posted January 23, 2005 Author Share Posted January 23, 2005 Check this out: http://www.graphics.cornell.edu/~v/fcd/ Quote Link to comment Share on other sites More sharing options...
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