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ok sick I've had this weird issue with my stag for a while now....

When its been sitting over night and its a cold morning or its been sitting all day at work and come out after and its a cold day some times when I start it it runs rough and idles low were talking 250 to 500 rpm, it then dies. If I re start it it then idles at normal cold start 1100 and everythings fine.... If while its idling rough and before I dies I give it a small rev to bring it up past 1500 rpm then let of the throttle it then goes into cold start and doesn't die and runs fine..... Anyone got any ideas? Apart from this it runs sweet no missing or anything... Should I try cleaning the aac valve?

Edited by kidafa
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Dunno but I will be cleaning mine soon and don't have a new gasket. Also check cold start air regulator. Saw a tutorial on cleaning/ adjusting that because it could give idle problems. Article also suggested blocking it off. Will try to find the link

I have it too. Also the squeaky belt annoyance.

I suspect mine is fuel/pump/regulator related as I can hear the pump buzzing for quite a while. Then it stops and idles ok.

Hope this thread gives some good ideas on how to fix.

yeah did u make a thread on this not to long ago hugh? I saw it but it didn't go far :angry: jamesrb25 is urs a stock fuel pump or after market? Same question to u hugh....? What is the cold start air regulator kiwi? Isn't that the aac valve?

ok sick I've had this weird issue with my stag for a while now....

When its been sitting over night and its a cold morning or its been sitting all day at work and come out after and its a cold day some times when I start it it runs rough and idles low were talking 250 to 500 rpm, it then dies. If I re start it it then idles at normal cold start 1100 and everythings fine.... If while its idling rough and before I dies I give it a small rev to bring it up past 1500 rpm then let of the throttle it then goes into cold start and doesn't die and runs fine..... Anyone got any ideas? Apart from this it runs sweet no missing or anything... Should I try cleaning the aac valve?

Check AAC, O2 & plugs - what's your economy like?

I have it too. Also the squeaky belt annoyance.

I suspect mine is fuel/pump/regulator related as I can hear the pump buzzing for quite a while. Then it stops and idles ok.

Hope this thread gives some good ideas on how to fix.

That sounds like the ATTESA pump - the fuel pump isn't really audible.

(which is normal on start-up)

I've also heard it could be an issue with the O2 sensor - not the whole problem, but a contributing factor. If the O2 sensor isn't providing a correct signal, then the computer hunts around idle for a while until it picks up. Mine used to do it too before I replaced the O2, and I haven't noticed it as much since then...

during cold start the ecu ignores the signal from the O2 sensor, just runs a preset fuel map in open loop. so O2 sensor really has nothing to do with cold start idle or start up.

i haven't had an issue with this on my stagea but the old R32 did, i cleaned the cold start valve and the IAC valve and it did help. i haven't been able to find a separate cold start valve on the stagea so i assume its apart of the IAC valve. but you shouldn't need a new gasket for it, i reused the one on the R32 which is and older and high km engine, didn't even get damaged during removal which was a bonus. i just put a bit of gasket goo on with it to be sure.

yeah did u make a thread on this not to long ago hugh? I saw it but it didn't go far ;) jamesrb25 is urs a stock fuel pump or after market? Same question to u hugh....? What is the cold start air regulator kiwi? Isn't that the aac valve?
No... to quote from the AAC valve tutorial http://www.skylinesaustralia.com/forums/Di...l&hl=idling (the links to the photos in this tutorial do not work but the photos have been added to the end of the tutorial): "Note, this is not the valve which controls cold start revs on idle, that valve is connected inline on the same intake pipe as the AAC valve but is situated under the intake plenum on RB25's"

Here is the tutorial for cold start air reg (this is based on R32 - positioning may be different on RB25 ...under intake plenum? haven't tried to locate it myself yet but will have to do so soon...):

http://www4.wave.co.nz/~lakewood/Skyline/ColdAirReg.htm

i have this exact same thing happening for the last week.

cold morning start, kick it over, save it with a touch of the pedal and everything's perfect. or let it stall and kick it over again, no pedal, idles perfect. any other time after the first start of the day is perfect.

i thought it might be the check valve in the pump not holding pressure in the fuel rail. so i tried priming it 3 times instead of once before the cold start. but it made no difference.

so i'm guessing its not a fuel issue. i'm upgrading my fuel pump soon anyway, but dont think it will sove this problem.

I will have to eventually clean out the two valves mentioned above. I was trying my best to avoid that ;)

O2 sensor with read about 0.00V to 0.02V at start up and stay that way till it heats up pver several minutes so it should have no effect on cold start.

It will start of at 0V, but build quite quickly up to around 0.1V and then steadily increase until it begins to smoothly swing between ~0.2V-0.8V regularly. If the sensor is crook, it will probably hang around at 0V for quite some time and it will effect the cold running. It may also swing erratically, and jump through 'non-consecutive' values (e.g. 0.2, 0.8, 0.3, 0.4, 0.5, 0.6 0.7, 0.6, 0.5 etc) as the ECU cycles the mixtures and sit at 0V for a few seconds often. They don't last forever, and are nearly 10 years old in any RB25.

Plug in a Consult system and check the values. You can also test the AAC if you have something like DataScan.

The IAC is also an important player in this equation.

yeah did u make a thread on this not to long ago hugh? I saw it but it didn't go far :happy: jamesrb25 is urs a stock fuel pump or after market? Same question to u hugh....? What is the cold start air regulator kiwi? Isn't that the aac valve?

Idid but got very few replies. Hope this lot help

I checked and gapped my plugs two weeks ago and their fine. The 02 sensor has no more than 30,000 on it so that should be fine HOWEVER after doing my dump pipe install i let the plugs dangle for a bit and they did get a bit melted :devil: Think it would still be working fine but would be good to check.... Any one here in SA with consult want to stick their hand up to give me a hand? COUGHbenCOUGH

Sounds like I best try cleaning the AAC valve and the Cold air regulator and see how I go from their? might be a job for thursday.

I've had this problem for around a year now I think. Damn thing doesn't fire on first crank. Idle is slow to pick up to 1100ish.

I started a thread on this also, I tried all the suggestions. I'm now wondering if the ECU has an issue or if it's a timing issue. Can't get more than 13 degrees(stock is meant to be 15) of the CAS. It's a massive pain. The car was fine for months then it all went shit.

Ive tried:

Coilpacks, Plugs, AFM, O2, ECU Temp Sensor, Fuel Pump, Adjusting Timing, Removed and Cleaned the throttle body and cold start valve, tried injector cleaner.

Sometimes it's a little slow to start even after its warm. All I've got left is injector's, ECU, hook up the fuel pressure gauge I have to see what's going on. And any other ideas people can come up with.

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