98 Gst stumbling....SAFC problem?? help

[90ATEGST]

Alright so i just got my gst a month ago....just now touched the safc because i thought the settings seemed a little off.....car had rc 550 injectors and whoever had the car before me had the hi-throttle correction at %-38-%-41 across the board on 17 pounds on a evo3 16g(car was running fine at this point)....so i messed with it and turned it up to about %-24 correction across turned the boost down to about 15 pounds and it stumbled all over itself when trying to go into boost....tried %-19 correction across and it did the same thing. so i put it back up to %-41 correction thinkin the car would act like it did previously(fine)...but no....it stumbled. so i got ahold of some stock 450's and set all the correction on the safc to %+-0....on 12 lbs.....the car still stumbles....WTF....Fuel pump?? Safc?? I'm stumped...

 

[JayRolla]

Go over the easy stuff first. Change plugs and wires if needed. Do a boost leak test. Make sure low settings and high settings on afc are at zero. Do a log to see what is going on.

 

[90ATEGST]

Go over the easy stuff first. Change plugs and wires if needed. Do a boost leak test. Make sure low settings and high settings on afc are at zero. Do a log to see what is going on.

yeah changed the plugs about a week ago...checked all the intercooler piping for any noticeable leaks and its ok but i guess looks can be decieving i'll check tomorrow...all low and high settings are set at zero...

 

[rrussell]

Do you have access to a w/b?

Its so hard to tell whats going on with out a O2 reading.

 

[wolf20043]

Make sure while you were in there you did not change the setting from Karmen. Mine did the same thing with the same results. Do yu get a CEL at all?
Mike

 

[90ATEGST]

yeah i have a cel on right now. i even tried unplugging the safc from the harness with the stock injectors in but then the car wouldnt rev past 2500 and the cel went away....so i plugged the safc back in so that i could drive it...

 

[wolf20043]

If you have a logger, pull the code. On the 1g, mine read as code 12. Go to your settings, and make sure Karmen is selected. Like I said, I just had this happen the other day and the car felt gutless.
Mike

 

[whiteflash]

What kind of plugs did you get? I recently had the same problem, started stuttering at 17psi, got some copper ngks and it went away...

 

[90ATEGST]

i'm runnin champion plugs...they're less than a week old...

 

[90ATEGST]

If you have a logger, pull the code. On the 1g, mine read as code 12. Go to your settings, and make sure Karmen is selected. Like I said, I just had this happen the other day and the car felt gutless.
Mike

unfortunately i dont have a logger yet

 

[wolf20043]

Well if it was running ok, messed with AFC settings, now cant get it back, it sounds like something got changed. I would rule that ou first.
Mike

 

[spyderturbo007]

yeah i have a cel on right now. i even tried unplugging the safc from the harness with the stock injectors in but then the car wouldnt rev past 2500 and the cel went away....so i plugged the safc back in so that i could drive it...

You won't be able to, unless you reconnect the MAS wire at the ECU. Remember, that when you install a SAFC, you actually cut the MAS wire. So when you removed the SAFC, the MAS signal was no longer reaching the ECU and you got dumped in limp mode.

 

[90ATEGST]

You won't be able to, unless you reconnect the MAS wire at the ECU. Remember, that when you install a SAFC, you actually cut the MAS wire. So when you removed the SAFC, the MAS signal was no longer reaching the ECU and you got dumped in limp mode.

thank you for that info....i'll try and go take safc off now that i know that maybe the car will run better. I tightened EVERY clamp on the car and checked and cleaned the spark plugs they looked fine...the car still spits and sputters and the feels like fuel cut at 5 grand...

 

[90ATEGST]

alright so i took the SAFC off and the stock injectors are on there and it's still doing this bullshit...i'm stumped....

 

[JayRolla]

Sounds like it is a lean condition. Make sure your getting a good 14v at the battery. If your having an alternator problem it can cause the fuel pump to go lean under boost. I had this issue when my regulator on the alternator started to mess up.

You could also have a failing fuel pump or not enough juice going to it. Is it rewired at all? Have you tried to add lets say 5% fuel accross the top to see if it helps? Without a wbo2 this is kind of like a guessing game. If your stumbling from running lean it can cause a lot of damage.

 

[90ATEGST]

supposeably the fuel pump is a walbro 255...i couldnt deny that it is myself just because i havent checked it out...it's whining pretty loud though..and whenever i turn my blinkers on i can hear the pump fluctuating along with the blinker...the safc is OFF of the car now....with stock sized injectors...and it's still doing this crap....

 

[90ATEGST]

Have you tried to add lets say 5% fuel accross the top to see if it helps?

yeah i did that before i took the safc off with no better results. did %+5 and even %+10...nothing worked...

 

[Polyol]

You won't be able to, unless you reconnect the MAS wire at the ECU. Remember, that when you install a SAFC, you actually cut the MAS wire. So when you removed the SAFC, the MAS signal was no longer reaching the ECU and you got dumped in limp mode.

Like spyderturbo007 said. When you took out the afc did you connect the MAS wire back

 

[90ATEGST]

everything is how it should be.....the mas wire is connected back the way it should be...the safc is completely off the car....it doesnt go into limp mode....it just stutters all the way up to five grand and the bucks like it hits fuel cut....

 

[JayRolla]

Turn the boost back to stock, take of the boost controller if you have too. Do a real boost leak test before anything else.

 

[90ATEGST]

turned the boost back down to 9-10 lbs with the boost controller....i'll have to make one of those boost leak testers...