Leaking Exhaust Pre Turbo?
 

Hi all,
2007 STi.

Ok, so for a while I've been getting a smell in the cabin mainly whilst stationery, and when I switch the car off the smell radiates from the OSF corner.

I have just replaced the drivers side rocker cover gasket as I could see smoke steadily rising from the drivers side under torchlight whilst engine running (can't see the smoke in daylight) so I thought the rocker cover gasket needed replacing, it was damp under the bottom seam so I replaced it with Subaru OEM.

Gutted though, there is still the same amount of smoke rising, it always smells like a sort of barbeque smell, and is grey smoke. All the time the engine is running, the smoke is there - switch off and it stops almost instantly. - Any oil burning off the exhaust would continue to burn in my mind. I've been out for a good long blast, so if it was oil from changing the rocker cover gasket, why would it stop instantly smoking once the engine is switched off? It's not like the heat shields suddenly go cold of course. Hmmmm...

Looking back (over my shoulder lol)...what coincides since I've been getting the smell / smoke, is a later boosting turbo (standard turbo), feels laggy until around 3.5 / 4k RPM then takes off. A built 2.5 STi usually is great bottom end. It's down on boost I reckon.

My theory is, a leaking exhaust flange or exhaust manifold gasket would reduce power? Not as much exhaust to power the hot side of the turbo, so a spiral downhill in performance, fuel economy is noticeably bad too. No CEL's. Revving on idle sometimes I think it pops or maybe slightly backfires....very slightly.

I can also hear a ticking on idle from the drivers side which makes me think exhaust gasket, but I'm not getting any high pitched sounds whilst driving, but it is pretty laggy....

I never even thought about an exhaust gasket leak until listening to it for a while today and hearing the ticking as I've heard it can cause ticking / power loss. The smoke is definitely coming from the side of the engine, rather than the turbo area itself.

Anyone else had this smoking issue that the rocker cover gasket didn't sort?

I've done my rocker gaskets, but will smoke abit as don't forget your undertray will have soaked up loads of oil and will be burning off as soon as your exhaust manifold gets hot.

Another option could be drivers exhaust manifold gasket, although when mine went car sounded awful.

Hope that helps.

I took off the undertray before I did the job as I knew I'd be dropping bolts and spanners, 10ml sockets....as it happens I didn't drop anything :) Doing the spark plugs a few weeks before gave me a chance to learn the area I was working in, and it's very tight.
But man the two breather hoses were stubborn to get off, brittle as anything and they needed the Alex Ferguson treatment to soften them up. New ones coming from ICP. I got some long bent nose pliers which have now already paid for themselves. Silverline from Homebase, seem sensible quality too.

Car sounds fine, so my theory is now that it's still oil residue burning off. Yes, been taking it for blasts etc, but you've got the cold air blowing in / over the manifolds etc, it's when it's hot idling at full temp and stationary is what you really need to get the oil burning off. Needs more heat cycles, but it's getting better. Another thing to keep my eye on...of course!

You'll get a CEL if you have a pre-CAT exhaust leak I'd imagine.

Ok, thank you.
Would it be a lean code maybe?