Installing Hks Fcd: Question

[Andi]

Installation has been confirmed!

So the question is now: whos used one of these before on an RB25DET and what setting did you use? Or do I have to jump onto a dyno and individually test each one?

Cheers,

Andy

Edited October 15, 2006 by OnGsTa

[paulr33]

yep spot on

its basically a signal bender as far i understand it

it probably just clamps the afm voltage when it gets near 4v ish

[Andi]

I thought I was right.

So just put the FCD "in between" the ECU and AFM right?

Hmm since we're on the topic, if it just keeps the AFM voltage at say.. ~4-4.5V what effects will this have? Leanning out of the car?

[paulr33]

it will run across the map instead of moving diagnoally down

it has the potential to lean it out more than normal

[Andi]

Could you perhaps elaborate abit more Paul?

Also, does the FCD keep the preset voltage permanently or does it allow voltage UP TO the preset?

[MsG_ChRiS]

Unique Auto Sports has useful guide i think that may help ...

i was looking at doing this mod to my car in the near future as i have a boost controller, fmic, and 3in split dump + metal cat goin on soon and from what i've read people have been getting great result from these FCD's (up to 37rwkw's!!)

If i do it I will have them install it ...

only problem is i have always been fairly sceptical of signal benders they kinda scare me.

neway will be interesting to see your results ... post em up after you install it!!!

end rant.

[Andi]

Unique Auto Sports has useful guide i think that may help ...

i was looking at doing this mod to my car in the near future as i have a boost controller, fmic, and 3in split dump + metal cat goin on soon and from what i've read people have been getting great result from these FCD's (up to 37rwkw's!!)

If i do it I will have them install it ...

only problem is i have always been fairly sceptical of signal benders they kinda scare me.

neway will be interesting to see your results ... post em up after you install it!!!

end rant.

Got a link to this guide?

I doubt the gains will be that much but I'd say it'd be a fair impovement if all you are getting is Rich and Retard once boost is increased.

Having said that I just installed my boost controller and have yet to tune it, so once I will I'll see when R&R kicks in and if so will install the FCD and get a dyno run/tune afterwards. Will be sure to post results.

[MsG_ChRiS]

addy is www.nismo.com.au

umm its in parts>gts>electronics>fcd bout half way down

to lazy to look but if you can't find it let me know

one of the guys from hot4's put a hks fcd on his 34 GTT and got 37rwkw's <-- no joke

[paulr33]

a fuel cut defender will add no power

it has no capcity nor does it do anything to "add power"

all it does is clamp the afm voltage so that the stock ecu doesn't hit its rich and retard protection.

[MsG_ChRiS]

ok my bad then hot4's magazine is printing falsified stories ...

darn i knew i shouldn't trust everything i read!!!

wouldn't stoping the rich and retard mechanism grant a gain in power (along with added boost, and supporting modifications) or am i wrong to assume this?

[paulr33]

no the "added boost" and "supporting modifications" is making the car make more power or "add power". the fuel cut defender is exactly that, a cut defender and its nothing related to fuel cut. its an excess airflow protection over ride device. magazines sometimes do get stuff wrong, or word it incorrectly.

it clamps the afm voltage at some point in a hope to avoid the stock ecu activating its excess airflow protection.

[MsG_ChRiS]

so basically it just smoothes out the power delivery???

ohhh now i'm confused

[paulr33]

it doesn't do anything at all. it doesn't smooth out the power or change it. it wont add 10rwkw or 1rwkw. it simply clamps the afm voltage when it goes near its peak value.

what happens is as you driving the airflow meter shows to the ecu how much air is coming in. when the value gets high on certain rpm levels (say near 4.5v, max is 5v) the ecu goes hmmm too much air is coming in, something must be wrong so it activates the rich and retard protection, to protect the engine. the result is a flat feeling and probably pops and farts out the exhaust. the ecu dumps timing and richens itself up to all buggery in a hope to make sure the engine is safe.

the fcd or "fuel cut defender" sits in between the afm and the ecu and says ok when i see 4.2v or higher (or something to that affect) ill actually tell the ecu its always 4.11v and won't tell it anymore that than.

so the engine runs along power comes on, air is coming in, goes to 4.11v and the fcd clamps the voltage and says to the stock ecu, hey its still 4.11v keep going, so the stock ecu does and thus you work around the stock rich and retard protection as the stock ecu never see's the higher afm voltages.

it wont magically add power or make the ecu think it can make more power.

there are similar devices like the apexi safc that do the same thing but they actually bend the afm signal to show less air is coming so that ecu goes ok so i see 3.1v of air but in actual fact there is really 4.2v of air so it uses more advanced timing and leaner fuel mixtures and as a result you make power.

there is no logical reason you would make more power by installing an FCD and nothing else. the only time you would see this sort of gain is if you are maxing hitting the rich and retard protection. and in this case the modifications that are on the engine, are causing it to make more power, as airflow makes power. the FCD is just tricking the engine to not activate its self protect mode

[MsG_ChRiS]

I think i understand the mechanics of these devices ...

but I'm not sure about the power thing ...

when the rich and retard protection kicks in it makes a dip in power ... the fcd's stop this from occuring don't they ? ... if they stop the dip in power would n't it give you a gain in power at certain points through the rev range and a smoother power delivery throughout the rev range, even on a standard car?

or is an fcd a waste of money?

[Andi]

Paul's got it right Chris. Funny thing is I just bought that edition the other day and have been reading it today, the reason why they 'gained' power was due to the fact that they were hitting rich and retard (as Paul stated) thus giving them a very dodgy power curve.

Have a look at the redline curve in the graph they put in the magazine, as soon as the power starts to build up, it suddenly dips because R&R is occuring - therefore limiting power.

So once they installed the FCD and eliminated the R&R problem, a natural power build up was able to be achieved and thats how they peaked at 197kw compared to the R&R limited 151kw.

[MsG_ChRiS]

ohh i think i may have hijacked the thread sorry ongsta ...

[MsG_ChRiS]

i'm not debating paul ...

i'm not a mechanic, but i do like to learn things he seemed to know so i though i might pick his brain ...

again sorry for hijacking

[Andi]

Wasn't implying anything about debating mate. I was just confirming/agreeing with what Paul said, to give you a better understanding.

Yep you do pick up power where before the R&R limited it, but what Paul is trying to say is that theoretically it doesn't ADD any power as say a bigger turbo would. All it is doing is 'allowing' the car to make a natural progressive power run without the limiting of R&R, which in this case is producing more power then when it was limited by R&R.

Its the same as an frount mount intercooler, fitting one doesn't actually INCREASE power. But if you're stock one is restricted and therefore limiting your power from its true potential, a bigger intercooler removes that restriction and in that sense ALLOWS your power to be increased but doesn't actually increase it.

P.S - don't worry about hi-jacking. It's all good mate, the forum is for the community to use.

Edited October 15, 2006 by OnGsTa

[Adriano]

A far better alternative is an Safc2, or if your on a budget, a jaycar fuel controller, they both do the same thing, except you can program them, hence use them to control mixture.

[Andi]

I've looked and experimented with the DFA in the past Adriano, but as the DFA will end up costing $100 for unit+controller and another ~$200 for tuning it ends up costing a fair bit more then the <$100 solution to remove R&R.

Well since Installation has been confirmed!

The question is now: whos used one of these before on an RB25DET and what setting did you use? Or do I have to jump onto a dyno and individually test each one?