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?

 

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

 

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-

 

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.

 

They made it work quite well for all the things they asked the poor dino technology to do. But it's not very flexible when you ask it to do much more (for instance, compensate for greatly increased flow or temperature changes)

-s-

 

Go with a PFC or other stand-alone ecu. I'd write more but my neck hurts =/. So sorry if I sound too blunt, I just wanted to put my 2 cents in.

Jeremy

 

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?

 

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.

 

the base map that the PFC comes with is plenty good for intake, DP, catback, without being tuned.

 

how much is a pfc?

 

yo whos in than las Vegas that can help ?

 

any body in the las vegas hood call me@ 682-5576 help me out ?

 

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.

 

"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

 

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