Unpleasant boost smell? Help!

[modmonster2008]

Hey, I have a 89 supra turbo. The exhaust flange gaskets have been replaced. there are no exhaust leaks on the piping. nor are there any known leaks coming from the exhaust manifold or turbo area as the smell does not seem to be present at idle or when the throttle is pressed. However when cruising down the road and im slowly building boost I start to smell a unpleasant odor coming from the outside of the vehicle, MOSTLY strong when the windows are open, but when they are closed and the vent is in FRESH mode not recirc there is no smell at all, where could the leak be coming from, it smells very bad. any help would be appreciated, thank you!

 

[Backlash2032]

What does it smell like?

 

[hvyman]

Im guess fuel or rotten eggs?

 

[modmonster2008]

Kinda smells like a very sour rich fuel smell. No codes. it only does it when building boost, or when actually boosting...

 

[hvyman]

Dp to turbo gasket good and not leaking? exhaust manifold studs not ripping out? No old gaskets in the rest of the exhaust? Scrapege?

 

[S.A. supra]

Cracked housing?

---------- Post added at 01:38 AM ---------- Previous post was at 01:36 AM ----------

Or manifold?

 

[modmonster2008]

Bump! Wouldnt a cracked housing or manifold have a loud exhaust note and heat in the engine bay? The car sounds fine and no other smells around the car during idling, i just notice it when im slowly starting to build boost, no other visible looking cracks on the exhaust manifold housing/turbo area. Anything else to check?

 

[modmonster2008]

bump! anybody?

 

[Moy]

do you have the cat still?

 

[modmonster2008]

yeah. but either way when i ran a straight pipe the smell never changed. the exhaust doesnt smell like it, but when im cruising down the road and maybe building up boost, i can start to smell it

 

[Moy]

take the cat off and see if the smell goes away. usually a rotten egg or sour fuel smell is due to a failing cat. The reason it'd do it more under boost is because the computer dumps more fuel, and the boost pressure increases EGT's. The combination super heats the cat and makes it stink worse.

 

[modmonster2008]

i ran a straight pipe before getting a cat system. it has the same smell, thats why im leaning towards the fact it may not be exhaust leak, cos the car has a unstable idle at times, maybe intake or boost leak?

 

[radiod]

Just a thought, you have anything plastic that might be a little too close to exhaust/turbo?

 

[modmonster2008]

bump, still has the exhaust smell. All exhaust related bolts/nuts are tightened down, no leaks at idle. im literally stumped...

 

[modmonster2008]

bump anyone? I replaced the exhaust manifold gasket,manifold to turbo, o2 sensor gasket, downpipe to elbow and catalytic converter (test pipe) gaskets im still smelling the exhaust leak, I did not see any cracks or warpage on the flanges in any way im literally stumped, i took it to various shops they could not identify where it was coming from, with cat or without it smells the same, and is worse when im boosting. Hope someone out there could help me pinpoint the problem...