Power FC vs. Super AFC
01-27-05, 10:24 PM
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Power FC vs. Super AFC
All right, I've been debating this for a while. I need something to adjust fuel because I'm planning on a DP/MP/race catback combo. I know that the PFC can adjust every single damn thing you could ever want, but I don't know much at all about engine tuning, and I'd be worried about doing something wrong and damaging something. Can a S-AFC for fuel and AVC-R for boost handle the mods enough to keep my car running strong? Or should I spring for the PFC like it seems most of you guys have, and spend three months straight studying the manual?
01-27-05, 10:42 PM
#2
you can buy the pfc, which is pretty much the S-AFC and the AVC-R combined, or buy the 2 components and learn to tune the same way as you would with the PFC. Either way you go, you'll be adding or subtracting small amount of fuel and or adjusting duty cycles. The PFC just throws in timing, just be careful with it or just don't touch timing except for making sure you don't have any negative splits. Go with a PFC.
Tim
Tim
01-28-05, 12:11 AM
#3
I would recommend the Power FC, dont' even bother with the piggyback, because the factory ECU is not good enough in the first place. Piggybacks can work well if your ECU is a good starting point, but ours is too old, the technology isn't viable. The ECU was updated in the '96 RX-7s, which did not get imported into the U.S. Here's a copy/paste from another post I made in the past regarding ECU's:
The best time to buy an ECU is as soon as possible. You can see power gains on an otherwise stock car by installing a modern programmable ECU and having it professionally tuned, and engine control technology has improved a lot in the past 10 years. Has anyone used a Pentium 1 computer recently? They were introduced in 1993, clock speed was 66-100mHz. Pentium 4 is circa 2000, for reference, with speeds of 1.4 GHz. Which technology would you like to use in your car?
Another significant difference between stock vs. aftermarket ECU's is the number of bits that they work with. The sensors in your engine output an analog signal, that is there is an infinite number or possible values within the range of the sensor (for instance, on a temp. sensor that can read values ranging from 0-5V, the sensor can output 3.957697457439245 V. The ECU must convert this to a digital number. It has to round it off somewhere. In an 8-bit system, there are 256 possible sensor readings in the given range. (2^8=256) That's not a lot of detail when you consider something like water temperatures ranging from 0-260 degrees F, or EGT's, or 360 degrees of output shaft rotation compared to the precise moment that fuel and spark should take place.
A 16-bit system can break that same 0-5V sensor signal into 65536 readings (2^16=65536), offering a much more detailed look at what the engine is doing. The same comparison can be made for outputs such as injector and wastegate control. 16 bits also offers more resolution available for fuel maps. Modern sportbikes have 32-bit ECU's, as does the RX-8. (2^32= over 4 billion possibilities within the sensor's range)
And we haven't taken clock speeds into account, either. I can guarantee you that a modern Palm Pilot has more processing power than the factory ECU of our mid-90's sportscars. If you're running a stock ECU, a '99 Civic has a more sophisticated engine management system than you. For my car, an ECU will be among the first $1500 spent on mods.
-s-
The best time to buy an ECU is as soon as possible. You can see power gains on an otherwise stock car by installing a modern programmable ECU and having it professionally tuned, and engine control technology has improved a lot in the past 10 years. Has anyone used a Pentium 1 computer recently? They were introduced in 1993, clock speed was 66-100mHz. Pentium 4 is circa 2000, for reference, with speeds of 1.4 GHz. Which technology would you like to use in your car?
Another significant difference between stock vs. aftermarket ECU's is the number of bits that they work with. The sensors in your engine output an analog signal, that is there is an infinite number or possible values within the range of the sensor (for instance, on a temp. sensor that can read values ranging from 0-5V, the sensor can output 3.957697457439245 V. The ECU must convert this to a digital number. It has to round it off somewhere. In an 8-bit system, there are 256 possible sensor readings in the given range. (2^8=256) That's not a lot of detail when you consider something like water temperatures ranging from 0-260 degrees F, or EGT's, or 360 degrees of output shaft rotation compared to the precise moment that fuel and spark should take place.
A 16-bit system can break that same 0-5V sensor signal into 65536 readings (2^16=65536), offering a much more detailed look at what the engine is doing. The same comparison can be made for outputs such as injector and wastegate control. 16 bits also offers more resolution available for fuel maps. Modern sportbikes have 32-bit ECU's, as does the RX-8. (2^32= over 4 billion possibilities within the sensor's range)
And we haven't taken clock speeds into account, either. I can guarantee you that a modern Palm Pilot has more processing power than the factory ECU of our mid-90's sportscars. If you're running a stock ECU, a '99 Civic has a more sophisticated engine management system than you. For my car, an ECU will be among the first $1500 spent on mods.
-s-
Last edited by scotty305; 01-28-05 at 12:20 AM.
01-28-05, 12:41 AM
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Suspicions confirmed...
I KNEW I should make an Apex-i ECU my summertime upgrade (right after my Crooked Willow dual oil coolers, since I live in Las Vegas). My Fluidyne rad. got me through last summer here - just barely.
Problem is I'll have to go to LA to get the Apex-i installed and tuned. Dyno tuning at XS Engineering runs around $95./hour plus LA's nice 8% tax. I figure at least $300.
Then I'll have to pay for tuning AGAIN when I get my Pettit large intercooler, fuel pump, M2 air intake box, and probably more fuel control stuff.
Wish I had the money up front to get it all done at the same time.
Thanks for confirming what I figured was true. The stock '93 ECU is the bottleneck for FD3S performance.
Problem is I'll have to go to LA to get the Apex-i installed and tuned. Dyno tuning at XS Engineering runs around $95./hour plus LA's nice 8% tax. I figure at least $300.
Then I'll have to pay for tuning AGAIN when I get my Pettit large intercooler, fuel pump, M2 air intake box, and probably more fuel control stuff.
Wish I had the money up front to get it all done at the same time.
Thanks for confirming what I figured was true. The stock '93 ECU is the bottleneck for FD3S performance.
01-28-05, 01:26 AM
#5
Originally Posted by 7Langit
Thanks for confirming what I figured was true. The stock '93 ECU is the bottleneck for FD3S performance.
-s-
01-28-05, 03:20 AM
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That's another of my main concerns. I see what you mean about the processing capabilities of both, but I would like to be able to tune it myself, as I tend to add modifications one at a time. Paying to have it done professionally every time isn't very appealing to me right now. Are you saying the PFC is no more difficult than the two piggyback units?
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01-28-05, 05:03 AM
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The super afc is not reliable enough to allow yourself a margin of safety for rotaries. This was from Chris Ott at rotary performance. The main utility of a AFC is to lean out cars that are too rich in order to make more power. It can't reliably add fuel. If you can't afford a PFC and tuning then you CAN'T afford to upgrade. It's cheaper than a blown motor.
01-28-05, 06:23 AM
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You'll read the PFC w/commander owners manual in 15 minutes.
and think to yourself " HUH ".....
YOu won't learn a thing about tuning from the PFC manual.
Well I didn't.
and think to yourself " HUH ".....
YOu won't learn a thing about tuning from the PFC manual.
Well I didn't.
01-28-05, 10:11 AM
#14
Rotary Enthusiast
"Can a S-AFC for fuel and AVC-R for boost handle the mods enough to keep my car running strong?"
No. But if you already have a chipped ecu, you can use the s-afc to trim fuel. The combo is better than a RRFPR, but crude compared to the PFC.
Search S-AFC and super AFC
No. But if you already have a chipped ecu, you can use the s-afc to trim fuel. The combo is better than a RRFPR, but crude compared to the PFC.
Search S-AFC and super AFC
01-28-05, 10:41 AM
#15
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The Super-AFC just doesn't work well on our stock ECU's. Fuel cut is so close to normal stock boost, and you have to manipulate the MAP sensor's output to do fuel correction, that there's just no overhead.
Trust me, I'm a big fan of the Greddy E-manage and I'd LOVE to use it on the FD, but the FD is just a poor application for *any* piggyback computer. It's just the nature of the stock ECU. Using a piggyback to fine-tune a chipped computer is doable, but you still have a lot of the flaws of the stock ECU - 3000 RPM hesitation, etc.
I eventually plan on going with a PowerFC. Plug it in, and all of a sudden the car runs the way it should - drives smoother, makes more power, no 3000 RPM hesitation, etc. It's a helluva lot of bang for the buck.
If you're still light on mods, you can get a PowerFC, install it yourself, and worry about the tuning when you get more mods. It takes like 10 minutes to install one - plug and play.
Dale
Trust me, I'm a big fan of the Greddy E-manage and I'd LOVE to use it on the FD, but the FD is just a poor application for *any* piggyback computer. It's just the nature of the stock ECU. Using a piggyback to fine-tune a chipped computer is doable, but you still have a lot of the flaws of the stock ECU - 3000 RPM hesitation, etc.
I eventually plan on going with a PowerFC. Plug it in, and all of a sudden the car runs the way it should - drives smoother, makes more power, no 3000 RPM hesitation, etc. It's a helluva lot of bang for the buck.
If you're still light on mods, you can get a PowerFC, install it yourself, and worry about the tuning when you get more mods. It takes like 10 minutes to install one - plug and play.
Dale
01-28-05, 04:05 PM
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All right, you've sold me, I'll go with the PFC. On APEX'is website, they say you need a separate boost controller that goes along with it to control boost. Does this come with the kits on rx7.com (where I want to buy it from) or rx7store.net? Can't seem to find it mentioned anywhere except apexi.com. Or should I get a PFC and AVC-R?
01-28-05, 07:06 PM
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Tim is right, you DONT need a boost controler BUT an aftermarket boost controler will do a better job in controling and ajusting boost if you plan to go futher later on.
Currently I dont have a boost controler, but I use the PFC and it works jsut fine.
Currently I dont have a boost controler, but I use the PFC and it works jsut fine.
01-28-05, 07:56 PM
#19
I'm a CF and poop smith
what kinda boost are you running with your mods? you do realize that if your getting boost creep or boost spikes wiht your system, even a powerFC will not help you out right? as for doing any kind of real tuning, PowerFC is the only way to go. personnaly i have a Super-AFC version 1 and it does look cool and has a great peak hold function for rpm, throttle position and boost as well as a boost curve graphing function but for the 400 bucks it cost me (I bought this a while ago when it first came out, yes even then it was a bit pricy)... i really wished i would have held out for a power FC. then again, i would not really need that as im running stock boost.
as far as controlling boost, why not try a manual boost controller first before spending big bucks on an eletronic one. (ball and spring type cost about 15 bucks to make yourself, do a search for it). also, if you cant keep boost down with a manual boost controller, your not goign to beable to keep it down with an eletronic one. eletronic ones are good for changing controllable boost on the go/fly from with in the cabin.
P.S. it is possible to keep boost stock with a dp, mp, catback exhaust system, i have all that +all metal piping+4X larger SMIC+intake and a whole bunch of other mods which are suppose to make you have huge boost spikes/boost creep with just a manual boost controller (ball and spring type, the bleader valve type's hole was just too small for my applications)
as far as controlling boost, why not try a manual boost controller first before spending big bucks on an eletronic one. (ball and spring type cost about 15 bucks to make yourself, do a search for it). also, if you cant keep boost down with a manual boost controller, your not goign to beable to keep it down with an eletronic one. eletronic ones are good for changing controllable boost on the go/fly from with in the cabin.
P.S. it is possible to keep boost stock with a dp, mp, catback exhaust system, i have all that +all metal piping+4X larger SMIC+intake and a whole bunch of other mods which are suppose to make you have huge boost spikes/boost creep with just a manual boost controller (ball and spring type, the bleader valve type's hole was just too small for my applications)
07-19-07, 12:18 PM
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hey guys. im currently runing a stock 1995 FD with just an aftermarket back box, and the ECU's already out of it's depth. it came with a midpipe and i got an induction kit already waiting to go on as soon as i can sort an ECU to cope. but ii'm confussed as to what to get. i keep coming back to the PFC but they're so expensive. the general opinion on piggybacks seems to be they're crap. i been looking at 2nd hand ecu's pre tuned. will these help if i pick one to my specs? how tuneable is the original 8 bit and can i upgrade to a 16? does anyone know of some other things i could do, even if its to keep me going while i save for an FC?
