Hello, I'll make this quick and concise. I drove my NA S5 FC on a 10 hour drive. For a good portion of this drive, I kept the car under 3800 to help with gas mileage (regretting it now, kinda). It wasn't until I was just a few minutes from my destination that I realized that the car was not pulling to redline. It would get above maybe 5500 and kinda just fall right on it's face, I couldn't push it past 7500 even if I stepped on it in second. Anyways, I did some research, threw some grease on my port valves and realized my 5th and 6th ports were not opening. I tested my VDI (actually broke the plastic end in the process) and that had no issues functioning, my A/C also works so I know the fuse for the air pump is in good shape. I'm currently 10 hours from all my major tools and will be flying back this Thursday, I'd like to know what all I can test in the meantime before I leave, so when I get back I can have the part ready to replace and fix this issue. I really don't have a lot of time and I'm hoping to nip this in the bud when I get back here because I'll be going on a deployment soon and wanna make sure this car is tip top before I go.

This little car is stressing me out, can anyone help me?

Edit: To add on just a bit, the car isn't losing any coolant, starts up hot FAST and feels like it's eager to pull up until it gets to that higher rev range. This is not a compression issue (I hope haha). I saw a few people mention something about cleaning the ports. Do they mean the port valves themselves or the actuators? Not sure how to go about doing that...

 

I would first check the ECU for trouble codes: https://fc3spro.com/TECH/HOWTO/ERROR...KI/kerror.html

If you get any trouble codes, than that should point you to where the problem might lie.

You didn't mention anything about your car's maintenance history. First thing that I would check would be the obvious such as the spark plugs, spark plug wires and fuel filter. Secondly, it might be a partially restricted exhaust. If you're still running the original cats -- I believe there were 3 of them on the S5 - than maybe one of them is clogged causing a partial restriction in your exhaust. I think these are the most obvious things to check first.

The stock Mazda air pump is mechanical belt driven.

Most usually the auxiliary port valves get carboned-up and will not function. As shown in the table below, the auxiliary ports open above 3850 rpm and only under load. The VDI valve only operates under heavy load.

 

you can actually push the 6 port actuators by hand, if they don't move, then you need to see why.
i've been lucky and the last couple have had the actuator stick on the pin of the valve, which is really easy to unstick.

if its not that then the sleeve is stuck, and if you are gentle and can get it to move, you're ok. if not the whole intake needs to come off and get cleaned out
probably replace the seals too

 

Hey there, I took both intake ports off and was able to pull the sleeves with ease. The actuators also turned freely. I applied penetrating lube to both and put them back on to drive the car. Unfortuantely, I'm still having the same issue

I swear the car feels just fine until you get to the higher rpms and it just stops trying. I just replaced my VDI solenoid as well because I broke it in the process of removing it to test it, but the issue persists and even the broken one tested fine. Really stumped at this point. I was hoping cleaning them up, pulling on the valves and turning the actuators would fix the problem, but nada. Anything else I can try?

 

Right, so quick update: The plunger valve things on the actuators DO open when I jumper the VDI solenoid to a 12v source. I ran the car, disconnected the brown connector and jumpered the solenoid itself and sure enough the ports moved as they should! I tried the grease test method once again, but alas, I still have no power over 6k and the ports show no signs of having opened. What am I missing here? Does this mean my airpump isn't working or my connector is acting up?

 

the airpump is what opens the 6 ports, so if they opened, its working.
i'm not sure off the top if VDI is pressure or vacuum.

but if all of the valves in the intake are working, then you'd want to look for like a plugged exhaust, or maybe fuel pressure/fuel filter

 

IIRC, VDI is pressure from the air pump as well.

 

So it could be my air pump?

 

If I understand correctly that with the car running, you apply 12V to the solenoids and the actuators to your 5th and 6th ports and VDI operate, then your air pump is working. It is the pressure from the air pump that operates them. The flow of pressure is controlled by the solenoids. Your problem may be with the signal that controls the solenoids. I would start looking into that and verify it is functioning properly. It may be tough though as those signals aren't based on rpm alone going by the previously posted chart.

 

you might just wire the ports open, and see if you have your top end power. if yes, then you can keep looking at how they are working
if no, then its something else

 

Update: It was my cat. Severely clogged. This was a used Bonez, removed it, decatted, reinstalled and she runs like new again.

Before that, I ended up replacing my fuel filter and spark plugs to no avail. I only realized it was a cat issue by looking under the car after a long drive and noticing part of the cat was glowing red from the heat.