Ok, I'm gonna try to do this without sounding like a complete idiot.

So I applied grease on the actuators and went for a drive. I could tell that there was something wrong as soon as it would hit 4k-5k rpm. Checked the grease and it didn't move. I take her to a shop by the name of Tekam which is known for having a lot of experience with rotaries. The mechanic hooks up an air compressor to the actuators and they open. He then does another test and tells me there's no back pressure from the exhaust and that's why they're not opening.

now, what confuses me is I thought S5s don't rely on back pressure to open the ports. Instead it's the air pump that opens them up....right??

Is the mechanic wrong? Do the ports just need to be cleaned? Does the air pump need to be replaced?

My car is completely stock btw.

 

Your mechanic is wrong. Only S4 NAs use exhaust backpressure to move the actuators.

The grease trick will only work on S4 NA actuators because they pull in to open the ports. S5 actuators push out, so the grease will not move. If you disconnect the vacuum line to the MAP sensor & free-rev the engine to 3800+ RPM, the actuators should move.

S5 actuators are controlled by the ECU, which has a solenoid on the emissions rack (6PI, brown sticker). The solenoid receives air pressure from the air pump & directs it to the actuators through the emissions rack. The VDI (variable dynamic intake) system works in the same way, and it has its own solenoid on the rack.

What is the problem you're having at 4-5k RPM? Non-functional aux. ports will make torque drop off sharply past the mid-range, so it will not pull as hard to redline. Non-functional VDI will have a similar effect.

 

Thanks for the info! I knew something wasn't right when he said it was due to the back pressure from the exhaust.

It just doesn't have that nice pull to redline. around 5k rpm there's a steady drop in torque. The difference is definitely noticeable at 6k+ rpm

How can I determine whether it's the aux ports or the VDI?

 

Free-reving the car by opening the throttle would be the easiest way to see if the actuators move. If you snap the throttle open quickly, you can reach 0 manifold pressure around 5k RPM. The trigger point for the aux. ports is 3800+ RPM & 0 manifold pressure. VDI is 5200 RPM and probably 0 manifold pressure as well.

 

If you disconnect the vacuum line to the MAP sensor & free-rev the engine to 3800+ RPM, the actuators should move.

^ Is this tip for an S5 engine or an S4?