S-AFC Fuel Management, 7afe options Options

[[Freemantle]]

I've recently acqiured a '95 ST as my new daily driver after some unfortunate mishaps with my previous vehicle (Honda Prelude). I've been a Honda kid since before I could drive, but I refuse to just give up on this car because it is "a 110 hp Toyota".

That being said, the Celica feels like it has no aftermarket when compared to anything I've driven prior. As a non-typical Honda guy, I'm all about keeping the car stock looking and using some shade-tree mechanic work to turn out some surprising numbers. I've got a T25 off a fresh rebuild and I'm ready to make this car a little more ballsy. I've done plenty of reading, I just have one issue.

The 7afe seems to have nothing as far as fuel management is concerned. I refuse to use an FMU (Boost dependent rising rate fuel pressure regulator) as "fuel management". It appears that the best kind of fuel management I am going to get is using the AFC hack, where I will use oversize injectors and dial them down with negative values with an AFC. Here are my questions.

A) How does the 7afe ECU respond to boost? The AFC will do nothing to correct ignition, it will just keep the car from seeing boost to dial down the map position (decreasing pulse duration to dial down the oversize injectors from choking the car).

B) Has anyone done this before?

C) What injectors fit the 7afe that can be easily obtained? What is the cc/min rate of stock 7afe injectors?

Thanks for your time.

[[Freemantle]]

Thanks for the input, I didn't knwo the GReddy E-Manage worked for our application. I've never toyed with that interface before, just AEM and Hondata/Uberdata.

I don't like the FMU because it dosen't take engine speed into account. Consider that an engine spinning at 6000 rpms @ 10lbs is getting nearly the same amount of fuel as an engine spinning at 4000 rpms @ 10 lbs. That means that you have the option of running pig rich in the middle of the powerband, or leaned out up top. A 12:1 FMU will most certianly do the former, giving you that "JDM y0" backfire when you're not even getting on it.

I have personal experience replacing head gaskets (and worse) on FMU managed cars. I've seen 2 D series and a B series bite the dust from FMU complications.

Again, thanks for the help, E-Manage sounds like a great idea. Timing control FTW.

[Dr_Tweak]

,Jul 26, 2005 - 10:13 PM]Thanks for the input, I didn't knwo the GReddy E-Manage worked for our application. I've never toyed with that interface before, just AEM and Hondata/Uberdata.

I don't like the FMU because it dosen't take engine speed into account. Consider that an engine spinning at 6000 rpms @ 10lbs is getting nearly the same amount of fuel as an engine spinning at 4000 rpms @ 10 lbs. That means that you have the option of running pig rich in the middle of the powerband, or leaned out up top. A 12:1 FMU will most certianly do the former, giving you that "JDM y0" backfire when you're not even getting on it.

I have personal experience replacing head gaskets (and worse) on FMU managed cars. I've seen 2 D series and a B series bite the dust from FMU complications.

Again, thanks for the help, E-Manage sounds like a great idea. Timing control FTW.
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While I certainly agree with you about using a piggyback over an FMU, you are not totally correct with what you said here. While an FMU does not take engine speed into account, that is a moot point since the ECU *does* in that it lengthens the pluswidths as the engine speed increases. The FMU provides higher pressure under boost conditions, which will increase fuel by a percentage all across the board. (In other words, more fuel will be spraying out at a higher RPM since the ECU is ordering longer pulsewidths, while it will be spraying less at a lower RPM.)

Bottom line is, an FMU can work quite well under low boost on engines using return-line fuel systems. Anything above 6 or 7 psi, or on engines with deadhead fuel systems, a piggyback at minimum is a must.

-Doc

This post has been edited by Dr_Tweak: Jul 26, 2005 - 10:22 PM