My counsin has a 2006 SS/SC and his only mod is an Injen Cold Air Intake. His car has the dreaded "WRX Sound" and when he starts it, it idles high and if he revs it up black smoke pours from the exhaust with the smell of rotten eggs. Also if he punches it while driving in the upper RPMS it will fall on its face like it is starving for fuel. To Top it off the engine had a new head, cams, valve springs, and downpipe put on 10,000 miles ago after it had the exact same problems. The dealers refuses to fix it unless it breaks so we are trying to fix it before it comes to that. I am leaning towards a clogged cat because of the smell and he also now boosts to 15psi, but im afraid its much worse than that. Any ideas?

 

cut the cat off

 

 

Pulled the downpipe today and the cat isnt clogged. Pulled the plugs and those are fine too. Any other ideas or things to try?

 

compression and leakdown test just to be sure

 

this kid i know had very similar problems and it wound up being the purge solenoid if i remember correctly