[Zerosoul]

BCC effect Air/fuel ratio?

does it effect A/F ratio in any way?

thanx

Jonas

 

[Steve Jarvis]

No. I believe the map (boost) sensor on our car is only used for the fuel cut and switching the fuel pump from 9 volts to 12 volts. The MAF and O2 sensor are used for you a/f ratio.

Later, Steve

 

[SpdRcr0]

So, even though the map sensor is not recongnizing the correct boost, it will still respond with the correct fuel??

 

[Marcus Frost]

The GReddy BCC taps the turbo pressure sensor signal. This signal has 6 functions. Fuel cut, fuel pump voltage (our fuel pumps have a 9v and 12v mode), EBV control, EGR control, idle speed, and evaporative emissions control. It does not, however, affect the A/F Ratio directly.

To answer SpdRcr0's question, yes, the GReddy BCC, HKS FCD, and FFCD mods are all based on fooling the ECU into thinking it is making less boost than .97 kg/cm^2 (at which point it will invoke fuel cut). The car bases the A/F ratio off of the MAF sensor and primary O2 sensor (NOT the secondary and NOT the turbo pressure sensor)

-m

 

[SpdRcr0]

gotcha.. thanks for the info... so I can tell that its a pretty safe mod to do..

 

[Zerosoul]

becuase I didnt tune the BCC in with a voltmeter, I just did the quick way driving the car and turn the BCC bit by bit untill I dont hit fuel cut anymore. thas why I wanna know if I somehow over adjusted the BCC and inputs more voltage then necessary to ECU, would it effect how the car performs?

 

[Josh S]

becuase I didnt tune the BCC in with a voltmeter, I just did the quick way driving the car and turn the BCC bit by bit untill I dont hit fuel cut anymore. thas why I wanna know if I somehow over adjusted the BCC and inputs more voltage then necessary to ECU, would it effect how the car performs?

If you adjused the voltage down too low, you ECU would never see enough boost to turn your fuel pump to 12V and the pre-spool of #2 could be messed up. Basically if the voltage were very low it would be like running the FFCD off mkiv.com. Seems like it you went slowly when turning the voltage down you would be off by that much, but it might be a good idea to check it with a volt meter

 

[Marcus Frost]

becuase I didnt tune the BCC in with a voltmeter, I just did the quick way driving the car and turn the BCC bit by bit untill I dont hit fuel cut anymore. thas why I wanna know if I somehow over adjusted the BCC and inputs more voltage then necessary to ECU, would it effect how the car performs?

You think that's the "quick way"? It took me 2 minutes with a voltmeter to adjust my BCC to the proper voltage. If you don't want to spend the money on a voltmeter (although I would recommend having one - they are a great tool), buy one and return it after you tune your BCC.

If you have the BCC voltage set too low, and you don't have the 12v mod, that could cause your fuel pump to be staying in 9v mode and would cause you to run lean (ie, loss of pressure) at high rpms. If the BCC voltage is set too high, you will hit fuel cut.

I'm asking you these questions (now for the 3rd time) for a reason, and you still don't answer them. Do you have the 12v mod? Are you in boost when experiencing a loss in pressure?

p.s. - make sure you get a DIGITAL voltmeter.

-m

 

[Zerosoul]

no I dont have the 12V mode done to the car...but now I am thinking of either doing it, or get the voltage correct
gonna have it checked out ASAP.
thanx for the input guys.

 

[Marcus Frost]

Goto a hardware store and get a DIGITAL VOLTMETER and adjust the BCC the PROPER way, no more than 4.3V. Do not do the 12v mod.

You also want to make sure your BCC is wired properly, because if not it could also be causing a faulty signal (ie, a vacuum/ffcd signal) which would also prevent your car from making the 9v to 12v transition.

-m

 

[supra178]

I think this weekend we should go and buy a voltage meter and check our BCC. I think that's the first thing we should check.

 

[Zerosoul]

Goto a hardware store and get a DIGITAL VOLTMETER and adjust the BCC the PROPER way, no more than 4.3V. Do not do the 12v mod.

You also want to make sure your BCC is wired properly, because if not it could also be causing a faulty signal (ie, a vacuum/ffcd signal) which would also prevent your car from making the 9v to 12v transition.

-m

DO or NOT TO DO the 12V mode? I thought you're telling me to do the 12V mode from your previous post?
I just did the 12V mode....should I change it back to normal?

after I did the 12V mode, I hear the fuel going thru the line after turning the car off with the key at ignition on, but when I pull out the key, the sound disappears.

 

[Andi]

The 12v mod for you is ok now as a diagnostic tool -- to see if your EGTs to down (i.e. if you're richer). At the top of DP you should only be seeing a max of 660-680 on runs to 150mph.

I assume you did secure/clamp down the hoses to the FPR.....

Andi

 

[Zerosoul]

Andi,

is it normal to hear the fuel going thru the line even after the car is shut down but with key at ignition-on?

 

[Steve Jarvis]

It's normal if you have done the 12v mod.

Later, Steve

 

[Zerosoul]

thanx..thats all Ineed to hear. but do you guys recommend 12V permanently? will it lower my gas milage?

 

[Mk4play]

bcc

I installed my bcc awhile ago. Once I installed it I wasn't hitting boost cut anymore but never used a voltmeter to adjust it. Everything seems perfect! Should I still check it with a voltmeter though?

 

[Marcus Frost]

Jonas,

No, I said I have the 12v mod and want to undo it. If you have the BCC there really is no reason for you to do the 12v mod. I would recommend against doing it permanently. Get a voltmeter and check your BCC, then you can decide if you want to do the 12v mod. The 12v mod will reduce your gas milage (one of the major reasons I want to undo mine, I run 104 all the time and it's stupid to waste it with this 12v mod that I don't really need)

Mk4play,

I would recommend getting a digital voltmeter to test your BCC. It really isn't that difficult, and a digital voltmeter is only about $20... pretty cheap for being such a useful tool.
-m

 

[Zerosoul]

I used a digital voltmeter and tuned my BCC to exact 4.3V, I wasnt too far off at 3.9V before...
havnt got a chance to test the car yet...
I am just gonna use 12V mode to test the car. will put back to normal after I have done my testing.

 

[Josh S]

Andi,

is it normal to hear the fuel going thru the line even after the car is shut down but with key at ignition-on?

I beleive that the pump always runs when the key is in the on position, just normally when it is in 9V mode you can't hear it.