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-   -   FCD Help (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/fcd-help-403055/)

REnder 03-09-05 08:47 PM

FCD Help
 
Does any one know how the Knight sport FCD hooks up? it has one female end and one male end and I figure it plugs straight into something but I don't know what.

Thanks.

BDentonFC 03-09-05 09:17 PM

Pretty basic. It plugs into the MAP sensor on the passenger fender. You then plug the factory harness into the FCD.

REnder 03-09-05 10:39 PM

Thanx

REnder 03-10-05 12:19 AM

ok i hooked it up but know the Stock boost guage doesn't work. is that normal? what do you guys think is a safe boost level? I hooked up a boost guage but its not a very high quality one and it says I'm running about 8.5 PSI. my car has ghetto intake, 2.5 or so exhaust ,fcd and BOV. I'm getting a turbo timer installed and was thinking about getting a manual boost controller [don't have the money for an electonic one]

the car seem to run alot smoother when I installed the FCD

Impreza2RX7 03-10-05 12:42 AM

What brand of gauge? I also wouldnt get a mbc if you're running the stock fuel system..

HAILERS 03-10-05 01:03 AM

If the stock boost gauge worked before, and now it does not, that should be a RED FLAG. You NEED to see if the boost/pressure sensors signal is/is not getting to the ECU. For obvious reasons.

REnder 03-10-05 01:11 AM

Why wouldn't I want to get a mbc? I just want to keep from running to high of boost. I'm trying to keep it reliable but with some performance. DOes anyone have a picture of the Knight Sport FCD so that I can compare?

NZConvertible 03-10-05 02:46 AM


Originally Posted by REnder
Why wouldn't I want to get a mbc? I just want to keep from running to high of boost.

I almost sounds like you expect a MBC to keep boost down, which it can't, under any circumstances. It can only raise boost. The only way to lower boost is to reverse your mods or port the wastegate.

REnder 03-10-05 10:21 AM

ok thanx for clearin that up.

BC-X 03-18-05 09:10 PM

just to clearify a little, by porting the wastegate, it will lower the boost? i thought it raised it ? or is that the intended purpose of the MBC in this situation?

NZConvertible 03-19-05 01:06 AM


Originally Posted by BC-X
...by porting the wastegate, it will lower the boost?

Yes.


i thought it raised it ?
No.


or is that the intended purpose of the MBC in this situation?
Yes.

Ottoman 03-19-05 01:35 AM

well techincally it doesn't "lower" the boost..

it just keeps the wastegate from being oeverwhelmed and the boost "creeping" up past what the wastegate is trying to keep it at...

the reason everyone is telling u not to raise ur boost, is because without proper fuel mods, u'll lean out and possibly damage ur engine...

NZConvertible 03-19-05 02:38 AM


Originally Posted by Ottoman
well techincally it doesn't "lower" the boost....

In most cases boost will be lower if you enlarge the wastegate.

Ottoman 03-19-05 05:49 AM


Originally Posted by NZConvertible
In most cases boost will be lower if you enlarge the wastegate.


If u mean Ripping out the flapper, enlarging the hole and putting in a larger flapper.. I guess ya u would be lowering the boost :P

when u said port wastegate I thought u meant the area leading out of the flapper into the exhaust itself... so the exhaust flows easier

syklone 03-19-05 08:38 AM


Originally Posted by REnder
ok i hooked it up but know the Stock boost guage doesn't work. is that normal? what do you guys think is a safe boost level? I hooked up a boost guage but its not a very high quality one and it says I'm running about 8.5 PSI. my car has ghetto intake, 2.5 or so exhaust ,fcd and BOV. I'm getting a turbo timer installed and was thinking about getting a manual boost controller [don't have the money for an electonic one]

the car seem to run alot smoother when I installed the FCD

Yes, the stock guage is now usless with a FCD. That is how the thing works. It tricks the ECU into thinking that boost is lower than it actually is, hence, your guage doesn't read acuratly now, if it did before (unlikely)

NZConvertible 03-19-05 04:01 PM


Originally Posted by Ottoman
when u said port wastegate I thought u meant the area leading out of the flapper into the exhaust itself... so the exhaust flows easier

"Porting the wastegate" means making the wastegate port bigger. That's all.


Originally Posted by syklone
Yes, the stock guage is now usless with a FCD. That is how the thing works. It tricks the ECU into thinking that boost is lower than it actually is, hence, your guage doesn't read acuratly now, if it did before (unlikely)

That depends entirely on the FCD. If you buy a shitty FDC that simply reduces the MAP sensor signal by a certain percentage, then the gause will become innaccurate. But if you buy a proper clamping FCD, the signal (and hence the boost guage reading) remains normal until just before the point of fuel cut, and then remains at that point. Since that point is at the top of the gauge anyway, it doesn't really make much difference.

Wait on, I just reread the post you were replying to. If you plug in a FCD it should not stop the stock boost gauge working. If the gauge has stopped working something is wrong. If the gauge is not getting a reading then neither is the ECU. You should not drive a car with a non-functioning boost gauge unless you're sure it's the actual gauge at fault.


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