Why am I still running rich?

[Dr.G]

I'm new to this board but some of you guys may know of me over at CL. I own a 99 RMM SC'd GS400. I'm running a 2.87 pulley, 310cc fuel injectors, stock fuel pump, Greddy Evo2 catback and SAFC-2 for fuel management. I've been tuned on the dyno three times in the past 4 months and after a few weeks of driving after getting tuned I get a CEL that comes back as the car running rich, not to mention the noticeable changes in driveability (ie, near stalling, slower acceleration, black exhaust at WOT, etc.) Can anyone please explain why this could be happening?

I know of three other RMM SC'd GS400s that have the same setup and fuel management (SAFC-2) as I but don't have this problem. I'm also curious if the cause of this problem of mine also has something to do with the fact that I was only able to pick up 4HP with the drop in pulley size (from 3.12 to 2.87) when I was anticipating at least 30-40HP increase? Any ideas or suggestions as to what I should be looking into?

 

[Red Supra]

I know that with 2jz-gte engines and stock ecu whatever changes you try to make below 4000rpm the ecu will override. What code does the ecu putting out? A vacauum leak will make the engine run richer. Maybe your SAFC is loosing it's settings for some reason. What is your a/f at WOT with boost?
Check to make sure that your belt is not slipping with the smaller pulley. You may need a one step shorter belt.

 

[Lextreme II]

Your exhaust upgrade is that before or after your tune. Increase exhaust flow will decrease your to anywhere from 2-4 psi. At 2.87" on the S-Trim should give you at least 12 psi with stock compression and stock exhaust. I would double check the wirings with the AFC-2. Seems like the ecu is resetting itself after you manually set up.