[Jarrett H]

When boost cut hits can the car still rev past? Does it stumble or does just not rev?

 

[ScrewDrvr]

itll rev through it to redline just stumbling all the way there though.

 

[rte. 17]

in the past, when my car hit that 12lb barrier, it cut like a bitch.. but once the boost fell below 12lb's, i could keep going.. but i couldn't floor it, otherwise i'd hit boost cut again.. 80 bucks later and an hour or so installing the grebby bcc - no more problems with boost cut!! =P

-jim

 

[quick]

When you hit boost cut it feels like a brick wall. You won't want to be hitting it a bunch. Just fix the problem with an $.80 diode from Radio Shack.

 

[MarksSupra33]

Agree with Quick, when I hit boost cut, everything stops, like I hit the brakes hard for a second. RPM's stop right there, and everything drops back down a good deal, then I can keep going. It can't possibly be good for the car, all that jerking around.

 

[MaliCali]

agreed with both above posts...

when you hit boost cut, the car can over boost for 2 seconds before the ecu cuts the car...and then the car pretty much like said hits a brick wall...and rpms stop there, and boost drops down a good amount....

i just installed my BCC this tuesday, and it seriously makes LOAAADDDS of difference, and its cheap, and its not THAT hard to install(and i hate electrical and wireing shit)...

-mike

 

[quick]

i just installed my BCC this tuesday, and it seriously makes LOAAADDDS of difference, and its cheap, and its not THAT hard to install(and i hate electrical and wireing shit)...

Exactly. And as I mentioned rather than spend $100 on a fricking BCC you can use an $0.80 diode from Radio Shack to acheive the same effect.

I wish I had known that before I added a BCC to my Fields harness...

 

[MaliCali]

Exactly. And as I mentioned rather than spend $100 on a fricking BCC you can use an $0.80 diode from Radio Shack to acheive the same effect.

I wish I had known that before I added a BCC to my Fields harness...

me too!! ive never heard of this, where can i find more info on that?!

 

[quick]

me too!! ive never heard of this, where can i find more info on that?!

You won't. The posts are always deleted due to the detrimental effects on sales of BCCs.

 

[Jarrett H]

A diode is a one way check valve for current flow. It also converts alternating current to dc. You can get zinear diodes that go one way with low voltage and the other with higher.

 

[ScrewDrvr]

all you need is a screw to plug up the hole on the air hose. Sure, sounds ghetto, but thats the easiest way to do it and its been like that on my car for over 3 years. Fuck and 80$ BCC.

Undo the hose, plug the hard end with a cap, then screw the other end with the screw. Finished.

 

[bahraini_zupra]

can somebody tell me how to do the DIODE mod thing somebody send me pm please with instruction and which diode spec from radioshack .

thanks guys .

 

[Hands On]

I have an alternate problem that feels the same as boost cut. I have the bcc and can run any psi all day long. But as soon as it rains I hit what feels like boost cut before the second turbo will spool at about 10 psi and 3800 rpms. I am missing my inner fender skirts so all of my wiring is exposed i'm sure causing the problem. I am still trying to trouble shoot what is getting wet and causing it. Back to normal after it drys out overnight. My big question is what is cut when you hit boost cut ie. fuel, spark, or air. I thought it might be my traction control butterfly acting up some how so I have it unplugged and the main butterfly pulley is on a cable to the pedle that I don't feel trying to close, so what is causing the brick wall effect?

 

[bahraini_zupra]

maybe ur car is missing at higher rpm ? is it like rev limiter ?

 

[Silver Supra]

You won't. The posts are always deleted due to the detrimental effects on sales of BCCs.

So - it's not on mkiv.com either?
Wanna put it on your site?

 

[BLKMGK]

The Boost sensor is used to turn the fuel pump onto full speed as well as boost cut. If you simply disconnect it then the pump will go full speed later. A resistor depending upon the value will either keep the pump off later just like disconnecting the MAP sensor or keep the pump going full speed all the time - neither solution is ideal. The BCC allows voltage from the MAP sensor to climb normally allowing the fuel pump to go high speed but capping the voltage before it climbs high enough to cause the cut. The BCC, of those solutions, is the better one. Another way to go might be to use a MAP sensor with a wider range. I know someone who has an AEM 3.5BAR sensor on their OEM ECU right now and they aren't hitting boost cut - however I'm not sure if he's getting proper fuel pump speed up either <shrug>. Oh, no I don't think that the 12volt mod is a particularly good idea - the OEM pump pulls a decent amount of amperage when run full speed and likely heats the fuel pretty good too.

 

[Espeefan]

I'm also firmilar with using zenar diodes as an over boost combatant. Zenar diodes are electronic devices that come in various voltage ratings. Basically what they do is dump any extra voltage that is higher then their rating to ground. So if you have a 4 volt zenar diode, it will not allow any more then 4 volts to get past it, no matter how high the voltage you try and run through it.

It's an old trick to use a zenar diode to chop the extra voltage off of the boost pressure signal that goes back to the computer. The computer will not see that there is more boost because the voltage never goes higher then (over boost conditions) allowed with the zenar diode chopping the excess off. Thus your MAP sensor will try to send an over boost signal, but it will never reach the computer.

 

[quick]

Exactly. The GReddy BCC does the same thing. - at about 100x the price.

To replicate with a diode:
<4.3 V for 93-95 cars
<4.1 V for 96-98 cars

Find the appropriate diode that corresponds to those values and insert inline.

 

[BLKMGK]

I'm also firmilar with using zenar diodes as an over boost combatant. Zenar diodes are electronic devices that come in various voltage ratings. Basically what they do is dump any extra voltage that is higher then their rating to ground. So if you have a 4 volt zenar diode, it will not allow any more then 4 volts to get past it, no matter how high the voltage you try and run through it.

It's an old trick to use a zenar diode to chop the extra voltage off of the boost pressure signal that goes back to the computer. The computer will not see that there is more boost because the voltage never goes higher then (over boost conditions) allowed with the zenar diode chopping the excess off. Thus your MAP sensor will try to send an over boost signal, but it will never reach the computer.

Yah, I'd forgotten about that - Zeners are pretty neat. WAY better than using a resistor for all of the reasons I mentioned before. Just go look up the value the BCC is supposed to be set to and get a Zener as close to that as possible without going over Oh, run high enough voltage and you WILL get past a Zener and it'll look like aq piece of toast too

 

[Espeefan]

Well yeah, eventually pushing really high voltage through a Zenar will burn it up if it's beyond the wattage rating.

So what do you guys recommend for wattage ratings? I know on my other MAP sensor equipped cars we use a 1/2 watt. Good enough for a Supra?