I don't think your supposed to adjust that without a gas analyzer? I used to mess around with mine when I had one and it didn't seem to make any difference so it must be a minor adjustment for emissions. It only changes the mixture at idle.
mine has a slot 4 a screw driver.... um... i made a big difference to mine.... i have bad injectors..... i put it on the leanest i could..... otherwise it hessitates like a bitch
I heard from somewhere else that it only affects idle which doesn't really make any sense to me, might have to investigate when i finally get the car on the dyno.
Sorry for Hi-jacking, I don't think theres much you can do typer unless you get hold of a adjuster with a screw in it.
Has the hole perhaps been plugged up so noone could adjust it?
As the screw sits recessed about 6mm on a mixture adjuster (on mine) and that one pictured looks like its almost flush.
Powerplant: Chipped stock ECU, 2044cc, 8.5:1, head intake enlarged and polished, exhaust manifold enlarged,
Balance-shafts eliminated, Intercooled, TC06 @ 10psi, 2.5" high flow exhaust system and dump pipe.