I only recently found about this GDI intake system recently. IM just a do it yourself mechanic, so to speak. BUt love n like learning automechanics:)
the car, has 84,000 miles on it. Never cleaned the intake, or throttle body. It was my dads car. He used too go too jiffy lube places. I aquired the car, few years ago, and have cleaned it up since...under the oil fill cap, oil was baked on. IGT was burning oil, about 75% a quart in 700 miles. I have done 4,000 mile oil changes since, better filters, and now the car burns only like 25% a quart in 4,000 miles. not bad! Last year, i did the transmission fluid. it was GREY and BLACK coming out. i didnt do the filter, i pulled the return line, turned car on, ran till it sputtered, truned it off, refilled with new fluid, same amount that came out. and the differential too.
The point...i am assuming the intake may or must be a mess! I do have a new gasket, felpro, but waiting to get some mroe money together, too get new or irngs and fuel injector cushions, autozone, as long as the fuel rail is guna be off.
I do run MMO in winter 6 months, and tcw3 3 ozs for 10 gallons, every fill up, shell 87 TT fuel. so....perhaps im better off running seafoam or B12 , spray into into the throttle body as car runs or manifold vaccum line? tan go through the removal of the manifold itself, and maybe just too find thiers no carbon buildup? or their might be.. why i started this post. i would assume the valves are clean then, from TRAV's answer. but the intake i dunno.