I have a 2003 WRX which is fully decatted. When I drive the vehicle I have no problems but if I am going down hill with my foot off of the accelerator I can see smoke coming out of the exhaust, then when I put my foot back on the accelerator I get a whisp of smoke and no more. There is no smoke when I am driving normally just when going down hill with my foot off the gas, any ideas????

 

It also doesn't start until I have driven the car for about 20 mins

 

Valve seals maybe? Sucking the oil in with vacuum

 

It does not appear to be using extra oil.

 

What colour smoke?

 

Blue I think

 

Blue = oil, would get your car checked out for sure.

Tony

 

I was aware its oil, but what I find strange is that it is not using any extra, I am taking it in to get it checked this week but just wanted an idea what it might be. The fan also comes on but it is not heating up any more than usual.

 

Doesn't take much oil to create a cloud of smoke.
If it's blue smoke on the overrun, I would say piston rings. You say it disappears on throttle?
You SURE just does it down a hill? Give it some boost and then look in mirrors for a wisp of smoke.

 

Yea sure, when i put my foot on the accelerator at the bottom of the hill I get a tiny whisp and then nothing

 

No smoke when foot down, foot off then a cloud of smoke?

 

Not a cloud, on overrun going down hill I get some, if its ticking over nothing, when I put my foot on the accelerator I get a little whisp and then it stops.