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Discussion Starter #1
Tried searching and "vague" is all I got. An FCD works by fooling the ECU into thinking that there is less boost being applied. Does this effect fuel delivery or anything else? It seems to me that if the ECU think's there's less air being forced into the combustion chamber then it will supply less fuel...
 

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loudest
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That is the reason that most people stay away from the FCD because of it causing lean circumstances.
 
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Discussion Starter #3
Please forgive me here, cuz I'm still a boost noob...but fuel cut happens at 10-12lbs right? How do people get around that?

I was already planning on needing to purchase a FCC, SAFC, and AF meter so that I could run 10-12lbs reliably...
 

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Acting my age
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The best way would be to do the Lexus AFM/550 mod.. Beyond that you could move to VPC territory.. The HKS FCD is not recommended by any tuner I know. If you cannot afford the 550's right away, get the lexus AFM and your S-AFC and run +20% across the entire RPM range.. (very specific! do not run any more or less, if you run 25% you will just hit FCO, less than 20% and you are risking running lean at high RPMs) This will allow you to run 12lbs of boost safely without leaning out. But dont get all crazy trying to run 14-15lbs without the injectors! I personnaly prefer the HKS S-AFR over the Apexi unit, but thats for you to decide.
 
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Discussion Starter #5
What's different between the apexi unit and the HKS unit?

12lbs is more than enough for me...so I'll probably go that route. Appears to be slightly cheaper, too...
 

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yeah thats me!
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i have an hks fcd for sale and its attatched to my ol ecu wiring. :)
 

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my car has the FCD wired in already. is there any way to just not use it? if i turn it all the way down will it cause fuel cut to occur faster? or does the ECU just use default setting?

i haven't tried to remove it yet so just wondering if i can turn it down, thats all.
 

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Broke Supra Addicted Fool
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If all you want is 12lbs you can run that before hitting FC. FC hits around 12-15 depending on conditions outside. But my car can run 12lbs all day long during the summer and occasional 14lbs on hot days... 12lbs and basic intake/exhaust etc. is a fun car easily capable of 14sec flat 1/4 times & better...

GL with your car ;)
 

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Dr Wheelspin Rh.D.
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Much safer to bypass FCO with something like the e-Manage where you can remove AFM signal to raise FCO and add injector duty cycle to return to the proper duty cycle.
 

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pfft ive run 15-19 psi with fcd for 1 year + now, still 150 compression in every cylinder...

Ang

BTW please put this away and look at it in a year...

12lbs is more than enough for me...so I'll probably go that route. Appears to be slightly cheaper, too...
 

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wastegate hose is pulled
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Bishop92T said:
Much safer to bypass FCO with something like the e-Manage where you can remove AFM signal to raise FCO and add injector duty cycle to return to the proper duty cycle.
:agreed:

Either that or Lex/550's to get around fuel cut.

You may want to retard your base ignition timing a couple degrees either way. Serzy was right as well, you may be within stock FCO at 11-12psi.
 

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it's a rod knock life
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SuprAng said:
pfft ive run 15-19 psi with fcd for 1 year + now, still 150 compression in every cylinder...

Ang

BTW please put this away and look at it in a year...
Be careful there. I suspect it was a bad tank of gas in combination advanced timing due to pulling fuel with the super afc that did me in.
My comps where 152 across the board and everything was in check. I am convinced that detonation can lead to connecting rod knock.

Oh, true that about placing limits on power, boost, turbo's.
You'd wish you went bigger one you get used to it.
 

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detonation does lead to rod knock ... think about, detonation is pre ignition, making the mixture ignite before the piston is all the way up, this sends the piston rod to smack down on the bearing and crank, causing MUCH more friction on the bearings...

Whatever if it breaks it breaks, what can i say? it hasnt yet tho, i hate the idea of teh lex afm and 550s, its such a band aid to a poor air meatering system... waste of money IMO esp for 300whp... I cant wait for that maft to come out, thats what ive been holding out for...

Ang
 
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Discussion Starter #16
SuprAng said:
detonation does lead to rod knock ... think about, detonation is pre ignition, making the mixture ignite before the piston is all the way up, this sends the piston rod to smack down on the bearing and crank, causing MUCH more friction on the bearings...

Whatever if it breaks it breaks, what can i say? it hasnt yet tho, i hate the idea of teh lex afm and 550s, its such a band aid to a poor air meatering system... waste of money IMO esp for 300whp... I cant wait for that maft to come out, thats what ive been holding out for...

Ang
oddly enough i was reading thought the sonic tech pages and i came across this, by Reg Riemer:

"Note: Pre-Ignition is not Detonation. Pre-ignition is an unwanted early explosion of the air fuel mixture in the cylinder before the spark plug was due to spark. In most cases with Toyota engines this is caused when the spark plug electrode or carbon deposits exceed 1700 deg F. When pre- ignition occurs the engines performance will fall off and the sparkplugs and pistons can become pitted or even partially melted with prolonged exposure to pre-ignition. "
 

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it's a rod knock life
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Detonation is more of a result of a lean condition. The mixture gets spark when it should. Only thing is there is not enough fuel to burn with the oxygen in the mixture. That results in a very rapid burn,high egt's and cylinder pressures. The combustion process doesn't stop there...piston material then becomes fuel at that point. Timing advance due to clipping the afm signal doesn't help. Not good.
 

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if this is true, how would detonation kill bearings then?
 

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Detonation is a collision of flame fronts in the combustion chamber rather than a single burn that propogates(sp?) smoothly. Preignition is premature beginning of the combustion cycle (i.e. before spark). Both result in tremendous ammounts of cylinder pressure.
 

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when this baby hits 88mph
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detonation is a massive shock to the pistons. it can break ring lands and blow head gaskets. if the shock was strong enough it would create a massive amount of force on the bearings. spun bearings are usually caused by poor oil flow, bad machining, etc. not nec detonation.
btw- the fcd has no idea about what boost level you are running. it just clamps the wave from the afm to the ecu so the ecu will never see the magical frequency of "too much air" and trigger fuel cut. the reason they use it is in case your actuator got stuck shut. if that happened you would just keep building more and more boost and kabooom.
for cheaper route id go afc/580cc/walbro pump for ~$800
some people use an afm bypass to let more unmetered air in but i would advise against this unless you know EXACTLY what you are doing.
agreed at 12psi you prob wont see fuel cut.

dave
 
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