there is a smalll screw on the underneath of the efi unit on the frst and its very hard to get to and see, any one know whats size it is?i think its a allen key screw but kinda confused bout what size?could it be a 4.5mm?

 

Not sure on size but it has a flat blade end not allen key if thats any help.

 

You cant actually adjust idle level with the screw though, its determined by the ECU.

You need to set the base idle but the rest is controlled electronically.