I was wondering if a boost controller can be used in place of a FCD in a car that I am getting ready to run bigger exhaust in order to prevent fuel cut due to increased boost levels?

THanks for your input

 

FCD and Boost controller are two different things. FCD tricks the ECU into thinking that there is less boost than really is. A boost controller allows the user to raise the amount of boost.

 

Yes, but a boost controller allows you to also set the maximum boost you will achieve, therefore also allowing you to -in a round-about kinda way- also adjust the maximum air and fuel injected into your engine -> adjusting A/F ratio.....

This is just speculation. If someone has done this and has data to prove it, all's cool. Otherwise, I'd bet my money on a FCD...

 

the problem with an FCD is it's just a bandaid fix. You are only tricking youe ECU not to cut off fuel supply. You are not actually fixing the problem of delivering the required amount of fuel to your motor to keep up with the increased boost levels. You will ruin your motor if you are running high enough boost even if you have an FCD, it will just take longer because it will never directly cut off the fuel supply you will just strave your motor.

My theory is that if you open your intake and exhaust car should automatically increase boost levels. If this is done wo any fuel mods its detrimental. But a boost control can monitor the highes levels. In the mean time while most of us need to research and save for delivering more fuel to the motor i thought a boost controller can keep an eye on the boost levels thus keeping the car reliable and safe.

let me know

 

Adjusting boost alone will not change A/F ratio.

I thought the reason you needed an FCD with a big exhaust was because the tiny stock wastegate couldn't bypass enough exhaust to take the boost back down to stock levels. A boost controller, no matter HOW good, cannot make a too-small wastegate flow more.

 

The FCD is just a clamp, holding the maximum voltage read by the ECU at 3,7-3,8 volts, therefore making the ECU "think" that the turbo is still making maximum boost allowed (8,6psi), and not exceeding it....

The boost controller wont allow you to directly alter the A/F ratio, but rather wont let your turbo boost more than you are allowing it to (with the setting of the boost controller). So, in the end, you might be boosting more, but the FCD will let you boost as high as possible, but you will not hit fuel-cut (and possibly running too lean and detonating), while on the other hand the boost controller wont let you boost more than you think its safe (i.e find out at what point your A/F drops too lean and dont let the turbo go beyond that point)....

 

Actually, the question is not entirely correct. If you put on a bigger exhaust, you will have less backpressure resulting in higher boostpressure. This will probably, depending on what kind of exhaust, get you in the areas where the fuelcut starts to work, as a precaution to save the enginge.
To get rid of this, you will need a FCD.
To use a boostcontroller, and thus raise the boost even moore in a controlable way, you will need the FCD. So, either way, you will need a FCD to trick the ecu NOT to engage fuelcut.

If you do all this, you will as a consequence run lean under boost.

Therefor, you will need to adress this problem with bigger fuel pump, larger secondaires, maybe a fuelcomputer to tune the Air/fuelratio such as the S-AFC or a fullblown aftermarket ECU.
So, as you understand, you need to solve all the problems, one by one, you cant just ignore the next step, since it is all connected.
Dont take any chances, play safe!

Cheers

////The Swede guy

 

A boost controller of any kind can only raise the boost level from what it would be if the controller weren't there. Thus if you have a boost controller set to say 10psi and you perform a mod which allows the turbo to produce 12psi, it will reach 12psi.
The amount of fuel injected is controlled by the ECU only, the turbo just pumps air.

 

I have an 89GTX. I plan on porting the wastegate (heavily) so I might only achieve 5psi without a controller. I then plan on using a avc-r to set the boost to 10psi. I already have a bigger fuel pump/Afc/FCD/and air/fuel ratio.

10 psi is only 1 1/2 psi above what the stock computer can handle. I can assure you with the bigger fuel pump and tuning the afc up a little bit, I will be well within fuel specs. Right now, I have the afc and midpipe/intake/fcd. Im hitting about 10 psi w/o controller or port. I have my afc tuned up about 5% accross the board after 4,500 rpms. My air/fuel monitor is still showing perfect accross the board, If anything, Im actually still running a little rich at 10psi , however, I would rather run a tad rich then lean.

But I think It will be reliable enough and I can run full exhaust/intake. Of course, your not going to have a super car. But with this setup and a few minor things, I will probably be dipping somewhere in 13.0 -13.5.

My best time with just intake/midpipe has been a 14.6.