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Top 2GNT Technical Turbo/Nitrous Tech topic #72504
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Subject: "basic sfmu afc question" Previous topic | Next topic
trbolipsJun-10-04 09:09 PM
Member since Jun 10th 2004
3 posts,
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#72504, "basic sfmu afc question"


          

i have 310's and an fmu with an 8:1 disc (i think- it's been a while)
and the car runs way too rich at idle and seems to lean out and then not get enough
fuel at only 7 psi.

was thinking of upgrading to an sfmu, but am unsure.
i remember reading something a while ago about a descrepancy in the size of the fuel line
and fittings, size 6 vs. size 4- i don't really remember.

i don't have too much money to tune
and i found a good deal on an s-afc
could i use this with my fmu to take down the idle fuel pressure?
at 7psi of boost and push about 65-70psi of fuel
and at itdle the fuel sits at 48 psi.
if i wanted to run 12psi of boost- what should i expect pressure wise running 310's?
should i get an sfmu anyway?
i remember a lot of posts about afc's not being necessary

any opinions/advice?

thanks

  

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jsupetranJun-10-04 09:14 PM
Member since May 04th 2002
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#72505, "RE: basic sfmu afc question"
In response to Reply # 0




          

Well, the thing you have to be careful about the safc is that if you lean it out in the higher rpms, it advances timing, resulting in the great chance of detonation. I know for a fact someone blew their motor that way on 2gnt.com. Although I think that it is okay to set idle fuel pressures with it, just have to be careful when the car is in boost. I can't help you with the rest of your question though. emoji


-------jezreel
1998 GS with hrc stage 2, sfmu, ml, prokits, egt, boost gauge, apexi tt, haydans tranny cooler, costum dp, dr. uber groundwires, dynotune fp gauge. gst muff, turbo spoiler
Boostin since Aug 03.

nothing like driving with the windows down and the music low: i love hearing the turbo spool, swwwhhhttt!!!!
thanks for www.kaptainmyke.com for the sig hosting emoji

  

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AdministratorStar Turbo TalonJun-10-04 10:10 PM
Member since Oct 21st 2003
8331 posts,
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#72508, "RE: basic sfmu afc question"
In response to Reply # 1




          

Originally posted by jsupetran
Well, the thing you have to be careful about the safc is that if you lean it out in the higher rpms, it advances timing, resulting in the great chance of detonation. I know for a fact someone blew their motor that way on 2gnt.com. Although I think that it is okay to set idle fuel pressures with it, just have to be careful when the car is in boost. I can't help you with the rest of your question though. emoji -------jezreel 1998 GS with hrc stage 2, sfmu, ml, prokits, egt, boost gauge, apexi tt, haydans tranny cooler, costum dp, dr. uber groundwires, dynotune fp gauge. gst muff, turbo spoiler Boostin since Aug 03. nothing like driving with the windows down and the music low: i love hearing the turbo spool, swwwhhhttt!!!! thanks for www.kaptainmyke.com for the sig hosting emoji


You cant set idle fuel pressures with a SAFC

Terry



96 Eagle talon ESI
Star Stage II - Boost/oil/EGT gauges

97 Eclipse
Greddy header/evo exhaust - Stage 2 6 puck Sprung hub MIBA clutch - Shortened shifter - Koni Yellows w/eibach prokit - Stillen Fr/Rr swaybars - ceramic intake - DEI Keyless entry alarm - Niche 17" Shoks

Waiting to be installed: Apexi AFC, HKS EVC IV, 450 Turbo injectors, SFMU/return line, GSX Front brakes (need rotors)

  

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AdministratorStar Turbo TalonJun-10-04 09:21 PM
Member since Oct 21st 2003
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#72506, "RE: basic sfmu afc question"
In response to Reply # 0




          

well first of all you need an adjustable regulator to lower your idle pressure for those injectors. with an 8:1 FMU you are maxing out your fuel pump if you are only getting 65-70psi. you should be over 100psi depending on the pump. If you get a walbro 255 you will see 100psi and that will solve your lean issue for right now. Best setup to run for the money if you want 12psi would be the SFMU 2.72 disc and SAFC for fine adjustments. Get the SFMU for now and add the SAFC later when money permits. if you are going to keep going after 12psi then its time to consider another alternative down the road. Look now so you are prepared 6 months from now. before you go to 12psi be prepared if you need to upgrade your injectors and internals. Anything above 8psi without precision fuel tuning will break the ring lands. you say you dont have a ton for tuning then you are going to need internals hands down.

Good luck

Look into:
e034 eic (8 injector setup)
Megasquirt...(uestions ask MRSLICK)
440cc injectors

Terry

96 Eagle talon ESI
Star Stage II - Boost/oil/EGT gauges

97 Eclipse
Greddy header/evo exhaust - Stage 2 6 puck Sprung hub MIBA clutch - Shortened shifter - Koni Yellows w/eibach prokit - Stillen Fr/Rr swaybars - ceramic intake - DEI Keyless entry alarm - Niche 17" Shoks

Waiting to be installed: Apexi AFC, HKS EVC IV, 450 Turbo injectors, SFMU/return line, GSX Front brakes (need rotors)

  

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trbolipsJun-10-04 11:31 PM
Member since Jun 10th 2004
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#72509, "RE: basic sfmu afc question"
In response to Reply # 3


          

yeah- i took that step already
it's built
and that's why i'm broke.
eagle rods je pistons 8.6

i have the fuel pump that came with the star kit- the 255 walbrogh (sp?)
i don't understand how i could be maxing out the fuelpump right now though
but i did think that i should be seeing fuel pressures up around mid 80 with 7psi
or am i thinking wrong because the injectors are larger?
again, right now i hit about 67

any idea about the size of the fuel hose (4 vs 6) ?
is there a difference bet. that of the fmu and the sfmu?
should definitely go with stainless right- any idea how much that runs
anybody know a place to find it?
same for the sfmu- best i could find was 280
anyone looking to get rid of one???

i remember reading about the timing issue with the safc
maybe it's more hassle than it's worth.

someone mentioned megasquirt
how hard is this to program?

also- anyone know anything about the howell computers?
would this get around needing a rising rate component-
will the computer compensate?
anyone have any experience with these?

sorry for the long post


  

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HadesOmegaJun-12-04 01:12 PM
Old School 2GNTer
4529 posts,
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#72562, "RE: basic sfmu afc question"
In response to Reply # 4


          

I tried exactly what you said you did. Instead of getting a sfmu I bought a safc instead thinking i could just lean it when it was at the lower rpms. Your car will run rich at idle and tricking the ecu isn't the best thing to do. With the sfmu you can lower the static fuel pressure and you won't be running mega rich and have that crazy fuel pressure. save your money and get a sfmu then get a safc to fine tune, basically the WOT fuel trims.


http://www.hadesomega.info -car specz and movies 95 Eclipse RS | 76' 280Z | 89' MR2 | 99 Neon | 91 Zephyr
Who sez FF can't drift?

  

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