I have played with it for a long time and there is still something im missing or have wrong. Here is the platform.

1999 GS Stock internals
Airwerks K26 Turbo (2" inch ports)
38lb injectors (400cc I believe?)
SFMU 2.72 Disc Dark Spring (6an line from rail to SFMU, 4an return to tank)
255 walbro HP
SAFC -II
60mm MP TB
Missing Link
EGT, AEM Wideband, Fuel Pres. guage, EGT, Boost)

FP Static 22 psi idle 18
Vac @ idle is 16psi
The car runs ok when I adjust the SAFC to -36% 1K -44% 2k -46% 3k -44% 4k and 40% 5k -38% 6k
6 out 7 in pressure

Crusing at 70 mph EGT's are 1350 about 3k, idle EGT's about 950

When ever i start it after its been sitting it revs between 500-1500 rpms constantly until about after 5 mins it then smooths out to 900 rpms.

Trying to get the wideband to stay within acceptable levels throughout the entire rpm range is a nightmare.

Im thinking maybe I should drop down to smaller injectors? (possibly 300cc) I rarely hit boost so most of my driving time is under normal conditions. I dont like having wild adjustments on the SAFC ( -40%+ )just to keep the car driveable. That way I could lower my SAFC levels and let the cars ECU do more of the engine management. Correct?

Those of you with similar setups what are your settings? Maybe i need to try a whole new base.

Am i using the wrong disc?
Are my fuel pressures way off?
I feel like this thing eats gas, i get about 20 MPG highway
Plugs are a little black but not fouling.

The only other thing i think might be messing with my wideband readings is i believe my turbo seals are bad and the excess oil in the down pipe could be affecting it.

What do you think? Thank you,

your problem is u need 6an return to the tank maybe . what is ur idle fp

I agree that the fuel return line needs to at least equal the size of your supply line. Secondly, injector size depends on any future plans to build larger. If you arent going to hit boost much and dont plan on a build then smaller injectors may be better if you want a 'less wild' SAFC setting.

What kind of fuel pressures are you hitting with boost??

Blown turbo seals may be hurting you as well if you know they are blown.
Oil in the cylinder increases your chances of detonation. Excess oil could be causing a problem.

I am not familiar with FMU's, but you may try some adjustments??
Are you getting any readings from your wideband at all??
What kind of plugs?? Heat range?? Gap??

20mpg sounds a little low, but you have to remember you changed how the engine performs.

So it seems your only problem is the 'idle surging' after sitting?
What are your Hi/Lo Settings on SAFC?

Just trying to get a little more info.

I would start off with getting rid of that 6an line and put a 4an in there. Im pushing close to 20psi on an SC61 with 4an lines with no problems and I know I could boost more.

Second thing "I" would do is get rid of the SAFC and just tune with the SFMU and your fuel pressure.

Before I MS'd, my first setup was SFMU and the SAFC. I tried and tried with that SAFC and couldnt get anywhere(maybe I just sucked at it). I finally said fudge the SAFC and started working with just the SFMU and my fuel pressure and everything started to smooth out. I got to the point where I was making a little over 10psi on stock injectors.

I know all cars and setups are different, but hey, might be worth tryin.

Good luck

PS-- Hows your O2 and coolant temp sensors?

Fuel line is stock except the short section from the Venom rail to the SFMU which is 6an then its 4an on back to the tank.

As for future I wont go bigger until I blow my engine and have to completely rebuild. So im thinking easily another 3 years with my current setup.

As far as detonation im not getting any.

from the wideband yes i get readings. i can stay pretty close to "Steoich" (spelling) at full throtle, but normal driving is the problem. i push the pedal slightly and it goes to so rich that its off the guage instantly until i release the pedal, and if i tune the safc to at different rpms to keep me within good ranges on the wideband, it will be good for about an hour or so of driving then the readings are totally off. for example tune to -38% at idle on the safc, .92 on the wideband and then an hour later at idle it will tell me im really lean 1.1 or rich at .78 and its just sitting their idleing.

as for plugs im trying to remember off the top of my head, i think they were NGK's, stock heat range, gapped to .40. Whatever the chiltons manual recommended.

Hi/lo on safc is is 35/80.

fuel pressure at boost 3psi is about 50 psi.
idle is 16 psi

as far as the SFMU the only thing i could do would be to turn up the FP but that would just make me even more rich and i would have to adjust my safc to -50% levels just to get the car to run.

at this point there is no way i can get rid of the safc. im way to rich and the SFMU FP is so low now that if i go much lower it dosnt work right. thats why i think i should switch to 300cc's then i should be able to back off on the SAFC.

Or the other route i have heard is drop back to stock injectors, 12:1 disc, about 40psi at idle and that should be fine up to 8psi.

and then just save the 38lbs injectors for when i have to rebuild.

My opinion would be to put smaller injectors back in and then use the FMU to tune it. After that is all done then use the AFC later on. That is my advice.

I wish I could be more help, but I use standalone...I dont really have much experience with FMU...a little with SAFC...but that is what I would do.

my opinion is to get a wideband 02 and ditch the safc . you dont have a widband you have a narrowband 02 gauge which is not accurate

yeah, i'm leaning more towards the smaller injectors as well. i dont run over 7psi so I may even go back to the stock ones since i have them lying around unless i can pick up some 300cc for cheap.

I am running a wide band though. AEM all in one guage unit mounted just before the cat in my down pipe. i have the regular A/F guage as well but we all know thats junk for tuning.


correct me on this. to run stock injectors up to 7psi with my current mods is it a must that i use the biggest disc in the SFMU because i dont have it. or can i still use the 2.72 disc (with dark spring)? isnt that 10:1 ratio? and then just fine tune with the SAFC II.

thanks

IF I were you...........

Zero out the SAFC from 2k on. Keep -50 at 1K rpms and see what your fuel trims looks like. Worry about getting the car to idle properly before driving it hard.

Watch the wideband while driving and use the safc sparingly. It's mainly there so you can Idle those large injectors.

\Also see if bumping up the FP 4-5psi helps with idleing, Some injectors don't atomize properly at that low of a fuel pressure.

I just re-read one of your posts.

At 3psi of boost you should NOT have psi going through those injectors.

You shuold have around a 3 psi rise rate not 10 like you have running. Waaay tooooo Riiiiich. No shit the wideband is going off the charts? :shrug