Since there are so many confusing threads about this I wanted to clarify. I'm taking this info from various threads and reliable sources on this forum.



For an S4 (86-88), you can remove the air pump and ACV and your 5/6 ports will still work properly if you have the backpressure pipe from your cat (or aftermarket presilencer) hooked up and give at least 2psi to the actuators. Most aftermarket exhaust set ups with this tube hooked up will still provide the needed backpressure to open the ports. There is no need to wire them open and most people will want to avoid wiring them open (or removing them) due to the loss of torque.



For an S5 (89-91), the air pump is still needed to open the 5/6 ports. Can someone who knows for sure give more detail on the S5's?



If you remove the air pump, you should also consider a dual belt alternator pulley to avoid the water pump slipping.

the dual belt alternator pulley is it good for s4 and s5 ??

Yeah, the same one can be used.

I've got a problem. Today, I removed my air pump and ACV. I wired the ports open. With the ACV disconnected, the engine would start up and run rough for like a second and then die. (BTW...I fabricated a piece to block off area where ACV was) I put the ACV back on (took plate off, of corse) and started it up. It would run as long as I gave it at least 3000 RPM's. When I test drove it, it died everytime I shifted up and didn't have it tached. I had to drive it to work today because my truck has slick tires and it's pouring. I had to think of something quick to keep it idleing, so I adjusted the throttle cable linkage until it idled @3000. Drove it to work. It sounds like a mad hornet. Smokes quite a bit more than usual also. What is making it do this? I don't think it should have to idle so high. I know there's something wrong, but can't put my finger on it. Did I leave something out.





Oh yeah, I have another question. If I want the port actuators to function properly, what do I do? What's the deal with the back-pressure line from the cat? If I just leave it like it is, will they work properly?

vacuum leak, put some gasket maker on your blockoff plate...

Yea, what 1Revvin7 said. I reused my old gaskets for the acv and egr block off plates and they worked fine. The ports will work on the exhaust back pressure so as long as the actuators are hooked up to the exhaust they should work. If you are not sure if they are working or not try driving with them hooked up and then not hooked up to the exhaust. You should be able to notice a difference in power when you get on it.

Thanks guys. I rigged the plate and yes it probably leaks (a lot). Where can I get block off plates? I need the ACV one as well as the EGR one.

this has got to be the most clear and up front explanation I've heard regarding this topic https://www.nopistons.com/forums/pub...IR#>/bigok.gif

www.racingbeat.com has them and I know k2rd.com has them for the turbo.

Thanks again, I ordered both of them today from Racing Beat. I let ya'll know how things work out when I put them on. I took my charcoal can off today. Where does the hose that comes out the bottom side go to? Mine looked like it had been cut off. (about 9 inches long). Can I take the two from the top off? I noticed one went to a place right under the oil filler and the other went under the firewall. (to the check valve @ the fuel tank I suppose). I guess what I'm asking is can I take them loose (and cap off) from the check valve and the place under the oil filler?