As you leave the shop, the extra 50 lb-ft or so you got from the software upgrade has you laughing hysterically. the increased boost makes your 2.0t Fsi turbo engine feeling like it's on steroids. until suddenly, the fun stops. You push the throttle and a premature "pssh" of pre-released compressed air catches your attention, followed by a nauseating check engine light. You slip it back in neutral and lightly rev the engine. it sounds fine. Back to the throttle, the car feels like a dog. the torque is gone. The power delivery feels lethargic, as if it's naturally aspirated. Chances are, you've just experienced the failure of your factory diverter valve.
The diverter valve found in the VW/audi 2.0t Fsi engine is plastic. it uses a flimsy rubber diaphragm that's become notorious for breaking when the boost pressure is increased significantly. although it never occurred on Project dub, our modified '07 gli, it can happen within the first few months or even the first hours of a new software upgrade if you're unlucky.
When the diaphragm breaks, pressurized air leaks through it and doesn't make it into the engine. however, several turbo specialists have a solution, including Forge Motorsport. its billet aluminum, piston-type replacement should last the life of the car and only costs $255 plus installation.
Unlike traditional mechanical valves that are a no-brainer to replace, the factory units are electronically controlled and set off a check engine light when failure occurs. But the install is still simple, thanks to all the parts supplied in the Forge kit. the only time-consuming aspect when fitting one to our audi a4 2.0t was accessing the hard-to-reach allen screws that secure the factory dV and solenoid to the compressor housing. however, the install on VW applications should be more straightforward.
Once replaced, not only will you regain all your torque, but boost response between shifts should be improved as well. the check engine light will still be there, but give it about a week of daily commuting and it will reset itself. Ours went out after five days.
Note: We actually broke the 90 plastic bend in the vacuum line when we yanked on the 3" vacuum hose. however, we fixed it by attaching another similar-size vacuum line to the broken piece and created another 90 bend using a capped-off T-connector. We were thankful for the extra line, connector and hose clamps since it was past midnight 85 eurotuner april
 Forge Motorsport's electronic...  Forge Motorsport's electronic diverter valve is a factory replacement piece for the 2.0t Fsi, with a billet aluminum construction and piston-type mechanism. the kit includes vacuum lines, a vacuum tap and electronic solenoid |  You'll need a 1/4-inch ratchet...  You'll need a 1/4-inch ratchet with small extension and 5mm allen socket, screwdriver, dikes, razor and a pair of pliers to tighten the zip-ties |  Access the factory diverter...  Access the factory diverter valve on the audi a4 from underneath. We started by removing this undertray -simply undo the eight screws with a flat-head screwdriver |