Whats the difference b/t the series five and series four FCD'S???? Anybody got a jpg of the series five wiring schematic that shows the pressure/boost sensor? Can you post it? Or tell us whether the wiring is the same as on a series four? As in BW, B, BrW, BrR??????Is the plug a different shape on the pressure/boost sensor???

 

I'd guess the S5 one just clamps the voltage at a higher level, since the fuel cut boost level is higher.

 

Scott,
Do you have a pic of your boost sensor connector? I looked through your website real quick and didn't happen to see one. I'd like to compare your S5 wire colors with the S4 colors. Thanks......

Jim

 

Has anyone built an FCD for an S5?

 

bump

 

Useless, twit, forum. Totally useless.

 

---^-------
* BR/B
G/Y BR/W

not sure what the * is?? I guess it only uses 3?

 

...

 

...

 

Yeah, it only uses three spots in the 4 prong plug, but a friends 90TII has two BR/B wires in the BR/B spot. I'm guessing one of the them has something to do with the boost solenoid. Why doesn't the online FSM have that wiring diagram that Scott has a pic of?

 

BrB is probably ground. BrW is probably the 5v ref and the G/Y is the output. Identical to the series four except the output wire is BrR on a series four and the series five does not have the 12v input the series four has. Thats the place where the * is.

I think there was/is a cavet that goes with the online manual at fc3s, that states he did not have time/inclination to do the wiring diagrams. Still very thankful for having the rest of the manual, even though I don't own a series five. So thanks for the online manual and the info above.

 

So, how does the IC work without 12V in?

 

I'm just guessing(covering my butt), but I'd say that it appears the that you could just find a source of 12v and string the wire to the DIY FCD and use that. The other three signals *SEEM* to be the same as on a series four. The only way to find out is to find a series five and see is the brown/white is indeed five volts, the black/brown is indeed a simple ground and the G/Y is the same as the brown/red on a series four. You'd have to make darn sure that no 12v went to the sensor though. Just to power the IC. Makes sense to me. Maybe I need to take a closer look, but it seems that way to me of the top of my hat. Disclaimer time: I will not now, or ever be responsible for anything you or anybody else destroys from reading anything I wrote or implied. See my lawyer Herb Goldstein for any law suits to be filed against me. You will be counter sued! humor, please.

 

I'll have to get under the hood of my friends S5 TII with a meter and start checking wires. I don't recall him having any external power source on his RB FCD (for the IC).

Nice disclaimer.......

 

First off, if you have an aftermarket-made FCD, you MUST get the right one for the car. If you plug the wrong FCD into the car, YOU WILL BLOW UP YOUR BOOST SENSOR AND MAYBE YOUR ECU. I've seen it happen.

With the Paul Stoaks FCD, you have to find a switched 12v source to tap into, as it's not supplied to the boost sensor. I don't know why you really need 12v, as it's a 5v circuit, but oh well.

Anyhow, I still believe that, for 90% of the people here, you really should get a pre-made FCD. It's tricky to make Paul's design, the instructions on the web are NOT complete and up to date, and you easily stand a chance of blowing up your boost sensor and ECU. It's not worth it.

I used to have a Stoaks FCD some time ago that an EE friend of mine built. I had from Paul some pages of revisions to the circuit that needs to be taken into consideration (that was MANY years ago, and no I don't have the revisions any more). It took my buddy, who's a qualified EE, a good chunk of time to properly build the circuit, then you still have to tune in the cut-out point.

After a year or so of having the FCD, I had problems with it from having the boost sensor wiring tapped into - the connections went faulty. This was about at the point I got the Fcon with it's own FCD, so it didn't matter.

Trust me, spend the money and get a professionally-made FCD. You'll save yourself a LOT of time, hassle, and future troubleshooting.

Dale

 

I talked to Racing Beat about the S5 FCD's and they have no idea.......they get them from Japan and that's all they know.

Anyway, the S5's plug in the exact same way the S4's do, so I don't see how an external 12V power source is gathered from the plug. There has got to be something slightly different with the circuit internally.

I'm gonna buy the S5 and break it open.

 

When you're done with it, send it to me.

 

No prob, rat.

 

Hold up...

Rat, in your sig it says DIY FCD under your 91 J-Spec TII. Is that a misprint or is there an S4 motor in there? What gives......

 

there's a diy fcd in there, but I don't trust it as far as I can spit it (I could probably kick it pretty far). I had an EE major build it for me, and he's played with clamping other car sensors as well. Though, it still uses the 12v source. I basically gave him paul's page, told him to make this, and let him do it. Then when I got it, I just ran an external 12v source. Haven't gotten to use it yet though because of my god damned MOP!

 

bumpin this thread because i wanna know if anyone else can shed some light. i want to modify an s4 mazdatrix fcd to work on my series 5