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Forum nameTurbo/Nitrous Tech
Topic subject440cc sfmu tuning help needed
Topic URLhttps://forums.2gnt.com/dcboard.php?az=show_topic&forum=i8&topic_id=55674
55674, 440cc sfmu tuning help needed
Posted by siueclipse, Sep-07-03 12:52 PM
ok.. right now i have the rc 440cc injectors in. my idle pressure is about 10psi.. i installed the smallest ring and disc but couldn't get above 40psi at 10lbs of boost. im now going to the second smallest spring to see if i can get the fuel back up where it should be.

any thoughts on this?

thanx
James
55680, RE: 440cc sfmu tuning help needed
Posted by ner947, Sep-07-03 02:02 PM
the 2.72" disk would probably be best for your setup. i have the 415's, and i have an idle pressure around 15 psi of fuel. it idles fine. you'd just need to idle around 10-12 psi (soooo low, but i know a 2GNT can idle around there, mine did when i was fooling with it, but not with perfect fuel trims)

you'll definatley need the bleed valve for the S-FMU too, but i bet you already have one anyways. i have about 3 turns taken out to give me the correct mixture under full boost.

also... i have modified my vacuum restrictor. if i left it in there unmodified, my S-FMU felt "laggy"... not sure how to describe it. so i tried it without the restrictor and it ran great, but way too rich. my solution was to double the diamater of the hole in the vacuum restrictor. i have had the most luck with this method.
55681, RE: 440cc sfmu tuning help needed
Posted by XtremeRS, Sep-07-03 02:24 PM
>
>also... i have modified my vacuum restrictor. if i left it in
>there unmodified, my S-FMU felt "laggy"... not sure how to
>describe it. so i tried it without the restrictor and it ran
>great, but way too rich. my solution was to double the
>diamater of the hole in the vacuum restrictor. i have had the
>most luck with this method.

So you just drilled out the restrictor a bit bigger? I get that lag a bit too..like you see the boost go up, but it takes a second or two to "feel" the car go..So now with that "mod", it boosts right away? Good info there nate..
55690, RE: 440cc sfmu tuning help needed
Posted by siueclipse, Sep-07-03 04:26 PM
well. i ended up using that disc.. my idle fuel pressure is 10 to 12 psi.. idles just fine.

15psi of boost feels very nice ;)

James
55713, RE: 440cc sfmu tuning help needed
Posted by DSMRoadster, Sep-07-03 08:19 PM
would the resistor you guys are talking about be the check valve?
55761, RE: 440cc sfmu tuning help needed
Posted by whodatt1, Sep-08-03 08:36 AM
no this is a little metal tube (looks like a reducer) that you have to put in the vacuum line going to the S-FMU.
55762, RE: 440cc sfmu tuning help needed
Posted by siueclipse, Sep-08-03 08:41 AM
i have that but dont have it in place.. why do you have to put that in there?

thanx
James