FCD questions

[Chris_87_Turbo]

I know everybody says to stay away from bypassing the Fuel cut as it there for protection. That's not my question, my question has anybody seen/tried this thing. Apparently its adjustable to modify the signal so that if you increase boost to say 18psi and OEM FC is at 12, this modifies the signal so FC doesn't occur until you want it too.

http://www.ebay.com/itm/DSP-Univers...Parts_Accessories&hash=item3a86e09def&vxp=mtr


Chris

 

[BryanDyer]

That's for cars with map sensors and we don't have one. the only "map" sensor we have strictly for the boost gauge but doesn't even affect how the engine runs. Our car runs off an afm.

 

[Suprapowaz!(2)]

Even if it is adjustable your ECU is set to activate fuel cut at a certain frequency given by your AFM. It called Frequency Out Max (fout max). It so happens that on my car that fout max is 2000Hz. Once I hit over that frequency FC happens. So if I had an adjustable FCD I could adjust it up to 2000Hz. Adjusting for anything over that would still result in FC. FC isn't based on how much psi you're pushing rather how much airflow is being metered by your AFM. Our AFM translates it into Hz and sends it to the ECU. ECU will only accept it until its fout max is reached and trigger FCD.

One person could be running 18psi on a CT26 50trim and not hit FC, while another is hitting FC running 9psi with a GT42. I hope I explained it correctly.

FCD is a signal clamp. It tells the ECU that the max airflow it sees is whatever you set it to (ex. 2000Hz). After that number your ECU will no longer compensate for more fuel. You will continue to flow more CFM with more boost and run leaner and leaner 'til... boom.

 

[Chris_87_Turbo]

It makes sense. I was just intrigued about the whole adjustability aspect that they claim. I have no interest in installing a FCD as I prefer safety and reliability as well as the right way to a bandaid.

Chris

 

[Poodles]

Yeah, the FCD was never meant to be used as a standalone component. It was meant to be used with the whole HKS suite of piggyback components (fyi, people ask why they did this, it's because it's an upgrade path)

 

[Chris_87_Turbo]

I would be really leery of using one and would probably just go the standalone route. I have used a few piggybacks over my years of racing and showing and a couple of standalones recently on other cars I've helped friends build. I'd have to say the answer to the "why did they do this" in reference to HKS was to keep people buying their components, consumers however I agree with you. Its an upgrade path.

Chris

 

[figgie]

Yeah, the FCD was never meant to be used as a standalone component. It was meant to be used with the whole HKS suite of piggyback components (fyi, people ask why they did this, it's because it's an upgrade path)

The Old FCD With the VPC and for adjustability the GCC. Yummy alphabet soup!

Folks,

the FCD was introduced when HKS had the 7m drag supra. waaayyyy back (25+ years ago). At that time, the stand alone computer. No such animal save for a electromotive and other ford/chevy "ECU".

 

[Chris_87_Turbo]

At what point though is an FCD needed? I Understand going for max power (I'm doing it with a Honda CRV, aiming for at least 600s or higher on a built motor and GT42R) fuel cut is gonna be a problem. But for your average supra that just does say a Lex/550 mod and jumps to 10 or 12 psi does that really need the FCD?

Chris

 

[figgie]

At what point though is an FCD needed? I Understand going for max power (I'm doing it with a Honda CRV, aiming for at least 600s or higher on a built motor and GT42R) fuel cut is gonna be a problem. But for your average supra that just does say a Lex/550 mod and jumps to 10 or 12 psi does that really need the FCD?

Chris

The FCD is needed ONLY in ONE VERY SPECIFIC configuration.

Only if you purchased and installed

HKS VPC
HKS GCC

then you add the FCD accordingly.

For all OTHER configurations. FCD is not needed.

 

[Chris_87_Turbo]

So doing say a lex/550 mod, and jumping to 18psi (I know you need more mods to go to 18psi just using some random numbers) the FCD wouldn't be needed? Would the AFM and ECU compensate for the changes? I was planning on doing the mod and going to 10psi or if I can up to 14psi. I do have a full 3" inch exhaust but that's it.

Chris

 

[Dirgle]

The lex/550 is a far better choice than the FCD. And the ECU is capable of doing some compensation giving you very near stock drivability. What doesn't get compensated for is ignition timing. So at the higher boost levels you're running more aggressive timing tables designed for lesser boost levels. This makes for some nice spool times on the turbo. But can cause detonation issues if you run into heat soak or a bad batch of gas.

 

[Chris_87_Turbo]

How much can it compensate for with the Lex/550 mod? Or what's safe?

Chris

 

[figgie]

So doing say a lex/550 mod, and jumping to 18psi (I know you need more mods to go to 18psi just using some random numbers) the FCD wouldn't be needed? Would the AFM and ECU compensate for the changes? I was planning on doing the mod and going to 10psi or if I can up to 14psi. I do have a full 3" inch exhaust but that's it.

Chris

Hmmm

Please Reread and let it sink in.

The FCD is needed ONLY in ONE VERY SPECIFIC configuration.

Only if you purchased and installed

HKS VPC
HKS GCC

then you add the FCD accordingly.

For all OTHER configurations. FCD is not needed and actually it is pointless save you want to grenade your motor.