Cold Start Annoyance

[LatinR33]

Hey just a small annoyance with my cold start. When starting the car up for the first time on the day the idle goes to like 600,700rpm kinda stumbles then just revs out kind of wakes up and then just warms up normally and yeah everything else is fine i know kind of picky but yeah just abit annoying. For the rest of the day turn the car on when cold warms up normal but if its not driven for more than a day or two then yeah does it again could be the cold but also wondering if it may be related to the tps?? It use to play up all the time but got it fixed but wondering if for like the first 5 seconds when cold this is going funny. maybe its something else but yeh what could it be.

[WazR32GTSt]

this happens to 99% of skylineowners on here

sorry, but there really is no cure - if you fin one, post it up here and help out the 10,000 people with the same thing!

[d00dz]

I have same prob. (well not really a problem but yeah)

Dont drive it for 1 week start it up revs to 1-1.1krpm. When normal idle is ~750krpm.

[LatinR33]

Ohwell had to ask thanks heaps, this website rules

[R33S2]

The way I understand this situation is,

a 'cold' air/fuel mixture is richer because of more denser air,

a 'cold' combustion chamber is hard to ignite,

a slightly lean air/fuel in a cold chamber is even harder,

whereas a slightly rich mix will wet/flood the chamber,

if the rev range is increased the mix is easier to predict/control,

this is the basic problem with any air/fuel mix.

I also suffered cronic problems lately in the cold, the coil packs were cracked which usually shows up in the high rev range when each pack is firing around 16 times a sec, but on a cold DEWY morning everything is damp and the cracks act as conductors until the heat disperses it.

[202.3rwkw]

apart from your aac valve on the manifold plenum there is a valve UNDERNEATH the inlet plenum/manifold that adds air according to coolant temp based on maps in your ecu... this valve can destroy itself and cause all sorts of problem!!!

this is diagnoed by crimping hose and listening for idle rpm change ie: should drop.

if this is the case.. you best plan of action is to make sure that this valve stays shut!!!

hopes this helps!!!!

[d00dz]

As I would say...

If it aint broken dont change it.

Dont worry about it. Unless it really annoys you or its an actual fault.

[azn_r33]

Check out the output voltage on your battery. I had the same prob but my mechanic did something to stabilize the battery voltage or thats what he said.

[Busky2k]

You got a PowerFC or is it stock?

[LatinR33]

stock as a rock besides a full exhaust and soon to have an apexi pod. and it only when i turn the car on the first time on a cold start. If i leave the car for like 3-4 hours in the cold and then start again then nothing. wait a day or two without starting then yeh goes funny in cold start for a few seconds then all good again. wierd ay.

[damono]

I have the same problem.. only started happening last few months

[LiQuid IcE]

i had that... now i have to hold the throttle down about 30% while i turn the key or it will just turn over and keep stopping.

I heard a bigger battery might help on a thread a few months back...?

[Cubes]

I had a similiar cold start issue on the stock ecu... It would fire then stumble requiring either a second or two for the rev's to raise or a slight tap of the accelerator.

I dropped a pfc in to it and bumped up the PFC's cold start cranking time and its now perfect. Cold start flicks straight to 1500rpm where it sits then slowly drops as the car becomes warm.

The std pfc's cold start values had it cranking over for some time before it would fire, I bumped it up more, it then fired straight away but would stumble as the stock ecu would, bumped it up a little more and now its all good.

The stock ecu also had slight idle hunt where as the pfc has a nice solid idle that vary's only 20-30rpm max.