I noticed everyone is always talking about their 5th and 6th ports working properly. Now, don't anyone yell at me, but WTF are you talking about? What 5th and 6th ports (what are they?). Thanks


Mike
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'86 NA

 

5th and 6th ports are auxillary intake ports that open up between 3500 and 4000 rpm. On your car they are activated by exhaust backpressure from a tube on the cat. If they are not functioning properly you will lose alot of top end performance. Hopefully someone else can add to this, because there is alot more to them, I just covered the basics.

 

Is that the tube that comes out of the side of the catalytic and feeds into a rubber hose on the side of the intake?

 

yes, that's the tube, except it doesnt go into the side of the intake, it goes into the air pump. (looks like an a/c compressor)... Now the aux ports quite commonly have lots of carbon buildup. They are held on by two screws each. Both are located on the passenger side of your engine block. They look like two solenoids with rods protruding out of each end which in turn rotates the rotating sleeve valves. Go through the trouble of cleaning them. They're probably stuck. It will be worth it.

 

Cant you just wire them open? Im new and thought i read that in the forums before so please dont flame me

 

Wiring them open will:
Reduce low end performance. There is no HP or performance gain as you are simply wiring open something that should be open above 3800 RPM anyway.

Removing them will:
Reduce low end performance, but give slight gains at very high RPM (read 6000-6500+ RPM). On a series 4 car this typically makes the Torque curve much worse and peaky, but it is not as bad on a series 5 car which will help compensate by the VDI.

 

On '86-88 N/A 6-ports - The large dia rubber hose that connects the tube from the cat to the intake just flows air to the cat. There is a smaller tube that comes off the metal pipe from the cat that feeds the 6-port actuators. Pull the little hose off the pipe and put 2-3 psi of pressure to it and see if your ports open. Most will be sticky unless they have been cleaned.

On '89+ cars the air comes from the air pump and not the exhaust. It is fed to a solenoid on the driverside and then back to the actuators.