Rough Idle When Starting Not The Usual

[13thracer]

I have a little issue, when i start my car when hot it runs really rough for about 15 to 20 to seconds then comes good. It will do if i leave the car parked in the sun all day at work and is technically a cold start the engine is cold but is a really hot day. It is even worse if i drive it on a really hot day park it and come back to the car and go to start it again it cranks for alot longer ("flooded it mate") and then starts sounds like a subaru and sometimes will even stall. I have to keep the reves up for little bit then it will run and drive as per normal. I dont have any other issues with missfires or anything at any other time eg: cruising, fullthrottle all sweet just starting when HOT.

Car is r33 gtst series 2

Mods - FMIC, Exhaust, Splitfires, Iridium plugs gapped at .8mm, Power FC, Standard BOV, Apexi POD. and a R34 turbo (12psi). Everything is standard. I use MOTUL turbolite 10-40w engine oil.

I figure it cant be the cold start valve cause it does it with engine temp at 30 or 90 and AAC colged up would cause issues all the time.

Any help would be great Thanks all

[DrewII]

change o2 sensor

[13thracer]

a very confident reply i like it, thanks man, was going to start throwing some fresh parts at this week o2 sensor was going to be one of them.

Cheers mate

[Cubes]

Mine used to play up and return bad economy until I shoved in another set of injectors. Economy pretty much went from 450+km's per tank to 350ish over night. Changed o2 no difference.

With another set of injectors it only stumbled ever so slightly which pushing in a little more fuel on cold start fixed.

I've now upped the fuel pressure slightly and it never stumbles old cold start even if I lean it right out; just takes a few more cranks to start.

There's a few threads on this issue. Check out the search button.

[13thracer]

Start during winter i only had it do it to me a couple of times and wasnt really that bad but as soon as the lovely queensland heat kicked i began having issues, i dont have an adjustable pressure reg and i really dont want to bump up fuel pressure as for there are thousands of skylines out there running similar setups to me that dont have an issue and would like to try and nut out the problem not just cover it up.