posted January 11, 2004 08:47 PM                

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Originally posted by Luni:
Also guys the only thing that I still think is incorrect is the notion that the ECU has maps for certain PSIs... I still think toyota would base the fuel maps off of air flow registered and not PSI.

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posted January 11, 2004 10:37 PM                      

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The voltage clamp sounds like an interesting idea, but again.. we're talking about readings over fuel cut which will result in, fuel cut! So how can you get around fuel cut, sending a signal higher than fuel cut to get into these MAX injector cycle's? See what I'm saying? Max injector cycle's are suppose to happen after fuel cut to prevent the car from blowing itself up.. but this has been my point from the beginning, we're artifically moving the point at where fuel cut happens with an FCD and actually shifting these ranges (from 12.8 to 17.2 on the #9 setting or something) upward in the boost range. So if I have an FCD set at 17.2 for fuel cut, my car set at 16psi well shit.. common sense tells me I'll never get into that MAX condition since I've just moved fuel cut up (or down in voltage readings on the PIM wire.. however you want to look at it). On top of that, not only am I not going to hit that MAX condition.. but my 16psi reading now is a lower voltage reading into the ECU thanks to the FCD than 4.4 (which is where fuel cut is initiated) so my fueling for 16psi.. might actually be more like the fuel maps for 12psi. WOWA! That scares me.

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posted January 12, 2004 02:14 AM                

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Originally posted by NuclearHappineS:

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The voltage clamp sounds like an interesting idea, but again.. we're talking about readings over fuel cut which will result in, fuel cut! So how can you get around fuel cut, sending a signal higher than fuel cut to get into these MAX injector cycle's? See what I'm saying? Max injector cycle's are suppose to happen after fuel cut to prevent the car from blowing itself up.. but this has been my point from the beginning, we're artifically moving the point at where fuel cut happens with an FCD and actually shifting these ranges (from 12.8 to 17.2 on the #9 setting or something) upward in the boost range. So if I have an FCD set at 17.2 for fuel cut, my car set at 16psi well shit.. common sense tells me I'll never get into that MAX condition since I've just moved fuel cut up (or down in voltage readings on the PIM wire.. however you want to look at it). On top of that, not only am I not going to hit that MAX condition.. but my 16psi reading now is a lower voltage reading into the ECU thanks to the FCD than 4.4 (which is where fuel cut is initiated) so my fueling for 16psi.. might actually be more like the fuel maps for 12psi. WOWA! That scares me.

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we already established the fuel comes from the AFM signal. FCD will hold your timing at max timing retard possible by the ECU without the presense of knock. Reaching 100% duty cycle will come from the fact that the AFM tells the ECU how much fuel to dump in. And that's how you reach max fuel, max timing retard and no fuel cut.

You can blow your car up by doing this.

You're running what 16 psi, and you have your FCD set to where you get fuel cut at say 25 psi... (because maybe you like to do 25 on track days or some BS).

Now you're at 16psi most of the time, and you have made the ECU think that 25psi is 12.5 psi (original fuel cut). Then there's about a 13psi difference ...assuming a linear voltage to psi adjustment in the FCD (which it isn't) ... but for the sake of arguement. when you are at 16psi the ECU will think that you are only at 16-13=3psi.

And there you go... BOOM.

Now if you're at 16psi and your ecu has cut at 17.5, then the 16 looks like an 11 to the ECU. 11 psi probably has a fuckload of timing retard ... and your car runs pig rich so i wouldn't worry

However when you're building up to 16psi... and you hit say 12psi on your way to 16. Your ecu things you're at 7 instead of 12...is there enough retard at 7 to handle 12psi of boost?

is there enough retard on the map at 4psi to handle 9psi of boost ?

I don't know.

All i know is you should build a circuit where actual boost is seen by the ecu until the point past which you don't want to show the ecu anymore. And clamp there and you'll get maximum retard without hurting the intermediate psi's

make sense ?

nuke

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Ya... I do get it. Well... shit, I want a stand alone.

Clayton

posted January 12, 2004 03:35 PM                

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Originally posted by NuclearHappineS:
And here is why i said mkiv owners xnay the FCD for the BCC :

http://www.mkiv.com/techarticles/bcc/why_bcc/Why_the_GReddy_BCC.htm

read up, enjoy.

In this article they do not talk about the MAP being used to control ignition timing (besides timing retard on fuel cut)... However they make the point hat the "FCD" alters the MAP signal (as shown in the articles i posted earlier) ...wheras the BCC does NOT alter the signal untill it clamps it)...

Why not to disconnect or plug your map sensor :

http://www.mkiv.com/techarticles/ffcd/freefcd.htm

Hope this solves it for you clay.

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posted January 13, 2004 11:55 AM                

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Originally posted by RedCelicaTRD:
The reason that supra owners dont use the FCD is because of the twin turbo setup. the ecu uses that signal to determine when to activate the second turbo. If they use the FCD the second turbo doesnt come on-line soon enough and it can damage your turbos. Since we dont have twin turbos we cant use their reasoning for why not to use the FCD over the BCC.

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