Hello everybody i own a R32 GTR 90 model and it is a Japanese circuit car which is heavily modified that i registered here in Brisbane. last night i was driving for about 5 min from my gf house adn i stoped at the lights and it turned off it did that about 3 or 4 times and when it finally stayed on when i was driving up until like 4500rpm or 5000rpm it runns very very shaky and it feels like its backfiring non stop and when i came home i noticed that it was smoking (black i think) on idle :( . Does anyone know what my GTR's problem could be? If it helps iv got like so many mods but ill give u some like the GReddy GT intercooler 700/400/103, Stage 3 CAMS, NISMO N1 Turbos, 3.5inch from turbo and 4 inch cat back exhaust, HKS F-con V pro gold engine managment comp, and so on. if somebody could please HELP ME it would be really appreciated. :)
Thank You!

Did you happen to see what voltage your battery guage was reading (centre cluster)? Honestly it could be anything from a dodgy wire or terminal connection on your battery, to being in desperate need of a tune (remember, the japanese weather conditions are very different to australia) There really are so many possibilities with it.

But seriously, if you're not that good with cars then i'd get it to a performance shop quick smart, but make sure it's one with a decent reputation for skylines & GTR's. As GTR's are such complex machines you really need to locate someone who is very knowledgable with them. I'd be inclined to check the basic stuff myself and if you still can't find it then don't drive it, have it towed to a workshop (must be a flatbed towtruck or it'll damage the 4wd system!).

Sounds like an Air Flow Meter problem or the BOV is playing up at idle.

Most common cause of your described symptoms is AFM's(using 2 of them) one will die quickly followed by the other.

The HKS F-CON V ECU cannot be tuned or modified in Australia either... HKS Japan keep that software for the JDM market only.