Blue/grey smoke after idle

[pacman_1219]

Evening all.

Got this odd issue with my R34 GTT. If I let the car idle for around 15 seconds or more (even when cold) and I jab the throttle a bit, a decently sized plume of blue/grey smoke comes out the exhaust. Doesn't smoke when idling alone, just when giving it some gas after idling.

No smoke on cold start or from what I know, normal driving. Not 100% sure about smoke on decel but I don't think there's any.

Any pointers on what I should start doing to troubleshoot it? Or if anyone has experienced the same I'd love to get some insight.

Cheers.

[GTSBoy]

Is it oil smoke or fuel smoke? They smell different.

[MBS206]

Or if it's grey, is it watery?

Does it do it after you've been for like an hour long drive it will still do it, or just near the start of the trip?

As GTS said, does it seem like oil (blue), water (white/grey) or fuel (black)?

Sometimes the colour can be hard to see clearly too for what it is, as GTS says, what's it smell like?

[pacman_1219]

Not gonna lie my sense of smell isn't the best. But it does look more grey to me. It doesn't smell like oil, friend says it smells like fuel.

[GTSBoy]

Well, in that case it is either completely normal accel enrichment, or it is completely abnormal accel enrichment, caused by a problem that we will be unlikely to be able to guess at this distance, but which will turn out to be f**king weird.

[pacman_1219]

Cheers man, I'm almost a little bit relieved in a way. Let the trouble shooting begin!

[Murray_Calavera]

8 hours ago, pacman_1219 said:

Let the trouble shooting begin!

What ECU are you using?

[Duncan]

Aside from the fact it is likely fuel related if it is black, the symptoms otherwise sound like worn valve stem seals. Oil gets past the worn seals when the engine is off and burns when the engine starts. If it happens on deceleration while driving (puffs of white smoke) that is another valve stem seal symptom because oil gets sucked form the head into the combustion chamber under vacuum with the throttle closed.

They can be replaced in the car if you have some way to keep the valves closed while working (eg compressed air into cylinders) but is much easier with head off.