OK heres the deal. I have 720 secondaries and a straight through exhaust. I get a raw fuel smell on boost. I am wondering if maybe its just an ultra rich exhaust smell that I'm not used to or if it is something else.



The engine only has like 3500 miles on it, all new injector o-rings and diffusers and intake gaskets and all that. There is something odd about it though. I think the smell gets worse as the tank empties. If I get into the boost with a full tank, it is OK, under a half tank and it stinks. I was thinking maybe something with the charcoal canister. (still need to investigate if this is 100% true)



Also, I have the ACV and air pump hooked all up, just no belt. I was wondering if maybe it is coming through there.



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The car did this before I put in the new engine as well, which kind of leads me to believe it is something attached to the engine and not the engine itself..

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Any help is appreciated.

 

ive seen this on the fd's and it comes from the fuel vapor part of the emissions system, somehow somethings letting boost pressurize and blow vapors out of the gas tank. so you need to look at the pcv setup, charcoal cannister and lines and stuff

 

you're looking for a bad/backwards check valve or something like that

 

I found the check valve thats right off the TID. It was stuck closed, well halfway at least. I cleaned it out and now it seems to work a little, we'll see if it helps. That valve connected to the oil filler is also easy to check so I'll do that next.

 

after a quick drive, I think the smell is much less, but I still got a whiff. Further testing is required. The clean valve still lets a little air back in through the wrong way, so I guess I should buy a new one. Doesn't look very expensive...

 

OK, got a full tank and it still does it. It does seem a little less in intensity after cleaning that valve, but it may be my imagination. The smell is still only on boost though, so I think that rules out the pulsation damper. Does the charcoal canister ever go bad? Maybe its not filtering the fumes like it should... Or maybe I should run with the gas cap loose to see if that helps.



In related news, I think my boost may have dropped around 2 psi. I was running 10psi when it was a little colder out, now it settles around 8.5. Not sure if it is the weather or a boost leak... All the gaskets are pretty new. I left the stock airbox with a K&N, so that cuts down on the boost spike from the full RB exhaust, right?

 

i have seen bad charcoal cannisters, not on fc though, everything else.



all my t2's boosted way higher when it was cold, like 13+ and then warm its like 10