Cold Start Quirrie Take 3

[WogsRus]

Well ok so my car still appears to have some cold start issues and surging on low TP% and high boost.

Basically for all those who don't know what's up read here.

http://www.skylinesaustralia.com/forums/in...=162820&hl=

This is the strange thing I found out recently. IF I open the acc valve to bring the rpm up to 750 at idle, following the procedure in the book, the car will start like a dog in the morning, it feels like it starts on 3 cylinders coughs and the rest fire up, this process of coughing and carrying on takes probably 30 seconds. Unless I put my foot to the floor, it will start fine.

If I set the idle to 650rpm with the acc valve bring a fair way in, the car will start fine, no problems no carrying on, hit the key, goes straight to 1200 rpm and sits there. Every time, then as it warms up it drops down ect.

SO I TRIED SOMETHING . If put the fuel pressure up to 60psi and opened the acc valve up, and it started fine, so it leads me to believe it is starving of fuel.

Once I get the new coils back, the car is going to Summers and Kutsie to sought out. I am sure the issue is simple, but no idea what.

The mechanics will be looking at it soon, but HAS ANYONE GOT ANY IDEAS???? HOW DO YOU TEST IF THE ECU IS PROVIDING ENOUGH ENRITCHMENT?

ALSO I still have the issue with the following:

I still have my issues with the low rpm high boost low TP% surging stuff, and no matter what I do to the fuel, it does not fix it at all.

Essentially the car stops and jerks around at 2500rpm and 3500rpm, and I do mean stop and jerk. This only occurs at low tp% and low rpm but high boost, above 12 psi. If tp% is high or flat to the floor the jerking is minimal?

HELP

[Pauly33GTS-t]

geez man you got a new QUERY and new problem every week. what injectors? stock i presume.

[WogsRus]

yeah stock.

Offcourse, you guys are free mechanics. LOL.

Nope it's simply the fact that down here in Tas the mechanics capable of doing a decent job are limited. Also i much prefer to find the problem myself and learn.

[LatinR33]

well cold start ups is common with skylines. Though 30 seconds does sound like a long time to fun crap. I know skylines that do it but for only a couple of seconds then warms up normally.

[Cubes]

Whats fuel pressure doing on start up? What adj. fuel pressure reg are you running?

I've always seen it as a fueling issue that in my case was sorted by cranking up the cold start enrichment (quicker start on initial crank) + ensuring 400rpm and start up load point is not too lean.

Lean out the start up load point (current rb26 pfc is load 6000 on startup) and it stumbles.

[WogsRus]

i don't have a PFC just an SAFC II and a maped computer.

[Cubes]

I know.

Have you checked fuel pressure on start?

[WogsRus]

yeah, 45 or something like that, fairly standard.

[Cubes]

So holds solid, doesn't fluctuate.

Bugger. Its not that then.

[Trooper]

I am having similar issues to you at the moment, < 250 kms per tank and driving me nuts.

I put a new fuel pump in recently and my tuner said that the first start is really rough, starved for fuel because the fuel pump is losing pressure overnight. It is meant to hold pressure so the fuel is there to start the car. Mine is a slow leak and he only found it because i left the car there for a few weeks so he could properly tune my cold start.

I need to sort my fuel issues out, not sure if this would contribute much to the fuel consumption.

So holds solid, doesn't fluctuate.

Bugger. Its not that then.