General Running lean

[blewbyu]

Does the screw on the bottom of the MAS have any effect on top end being lean? How about the adjustment screw on the throttle body?
I cannot get my car to stop running lean over 5000 rpm.
I have a 97 gst with a TD05, greddy evo 3" catback, 3" high flow cat, hk34 bov, rc 550's, walmart 255 pump, hc's removed, injen intake, s-afc. I'm running 15 psi boost, which is as low as it will go.
Setting my afc higher gets me nothing but faster fuel cut. Should I shoot the car and start over?

 

[Turbo Guru]

What type of fuel pressure regulator do you use? I don't see a fuel pressure regulator in your above mods list, your Walbro may be over-running your stock FPR. The addition of a upgrade fuel pump, larger injectors, and S-AFC should stave off fuel cut quite effectively. You do however need an FPR to set your base pressure, the stock one will not do the trick. If you do have an aftermarket FPR I would think you would be running rich and use the S-AFC to lean it out, which would further reduce the chances of fuel cut.
What type of device (ie- DSMlink, A/F gauge, EGT gauge, etc...) are you using to determine the lean condition? I see that your car is 2G, what turbo (TD-05 could describe many different ones) do you have? (ie- T-25, 14b, small 16G, Big 16G, etc...) The BISS screw (the one on the throttle body) is for idle adjustment. The screw on the bottom of the 2G MAS question would have to be addressed by someone else (I am not quite sure what it does, mine is still capped, And I don't want to give you bad or incorrect information.) Answer the above questions and we should be able to help you to determine the problem.

Joe

 

[blewbyu]

I installed the B&M upgrade kit on my factory regulator. I have a fuel pressure gage which is not installed yet due to the fact that i cannot get the bolt out of the top of my fuel filter. So i guess fuel pressure coould be part of my problem. I have an auto meter a/f ratio gage and i'm using the blue wire from my afc to check my oxygen senser voltage. i do not yet have an egt. My turbo is a td05 16g. I noticed today that the little block that attaches to the adjustment screw in the mas is missing. I'm not sure if this piece fell out when i removed the hc's or what. I reinstalled the hc's today in hopes of richening things up a bit. was that a wise thing to do?

 

[Turbo Guru]

Yes, IMHO putting the HCs back was a smart move. Get the gauge installed and let us know how it turns out or if there are still problems.

Joe