My buddy has an s5 n/a, and it feels like it runs into a brick wall at 6k rpms. It feels almost as if it is being rev-limited there. Anyone have any brilliant suggestions as to what this may be about?

 

Could be fuel pressure/ volume, fuel filter, 5th/6th port actuators not working, VDI not working. Is the air pump and belt still on the car and working? the VDI actuator should be getting anywhere from 1 to 2.8 PSI above 5200 rpm. It uses pressure from the air pump to activate it as well as the port actuators. There is a solenoid for the port actuators and the VDI actuator that sends the pressure to the actuators. Check for misrouted or cracked vacuum hoses, especially where the hoses go around the rear corner of the intake manifolds. They get a lot of heat soak from the exhaust manifold and will crack and leak pressure.

 

Would all of those cause the car to not be able to rev beyond 6K? Thanks for the speedy response!

 

Yes. The exact same thing happened to mine. I had a cracked hose to my 5th/ 6th port actuators. I checked it by using a vacuum "tee" in the line going to each actuator. The hose that I connected to the tee went to a vacuum/ fuel pump pressure gauge (from a parts store) and I tucked it underneath the driver's side wiper blade and drove the car while watching the pressure on the gauge. No pressure until I replaced the cracked hose. There is a noticeable difference in power with the port actuators and VDI working.

 

im the guy with the s5 that doesn't go past 6000, a buddy of mine unplugged my pressure sensor, turned the car on, and plugged it back in. now it goes well past 6000 but it hesitates now, like i feel the car pull but after 6 it doesn't pull as strong, but im pretty sure its my VDI, imma check it out today