After removing the airpump on an S4(86-88) n/a, you need to get a dual alternator pulley to prevent waterpump cavitation at high rpms.

You must also get rid of your cats as they will clog without the air injection supplied by the airpump.

When you remove the cats you need backpressure from the exhaust to activate the 5/6th intake ports@ 3800rpms on n/a(s) only, turboII are 4 port motors. Most aftermarket exhaust companies supply a vacuum nipple on a cat replacement pipe to supply the backpressure. If you make your own pipe just weld on a bung or vacuum nipple and connect the hose from the ports.

If you want, you don't have to, you can now take off and block off the air control valve, its located on the lower intake manifold, and a hose goes from the airpump to the valve. K2rd sells block off plates, make sure to also use some gasket maker on the block off plate. Now just cap off the vacuum lines that were running to the air control valve. The air control valve injects air into the cats.

You can also remove the air silencer. Its hidden under the windshield washer resouvier. When the air control valve is not injecting air into the cats it is being bypassed to the atmosphere and the air silencer just quiets it down.

People remove the airpump to free up some hp(parasitic drag) and make it easier to work under the hood and less slop in the way.

You cannot remove the airpump on s5 n/a(s) as it is needed for proper operation of the VDI, unless you want to mess around with electronic activation..

S5 turboII(s) do not have the vdi so you can scrap it.



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where do you get a dual alternator pulley?

Rotorhead



Racing Beat



Mazda Racing



Rotary Performance



Mazdatrix



and Banzaitoyota sells them

Do i have to remove all 3 cats or just the pre cats and leave the main? Also i'm debating the racing beat or apexi n1 dual exhausts, which do you think would work best when removing the airpump and acv?



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You can remove just the pre cats. If removing the main cat, you should keep in mind your backpressure pickup tube still needs to be hooked up.



Both exhaust systems are good quality. Its a matter of opinion. I prefer RB for the more stock appearance and the Apex N1 I believe is one of the loudest out there.

if u were short on time and wanted to free up more power could u just remove the belt to the a/c instead of removing the whole thing

86 fc

ok i took care of my ac. now i am on to a new question. i have a bad exhaust leak at my cats so can i just replace my cats with a strait pipe and keep my stock mufflers on withough dealing with the o2 pump?

You can but you need something to activate the auxillary ports unless you wire them open which sucks IMO.

do you have to have a gasket for the ACV block? if not, ****, i'll make one.

Yes you need one.

Can you remove your airpump if you have a high-flow cat or would they still clog?



In an s5 the airpump is needed to actuate the vdi and 5th and 6th port. is there anything else it is needed for? Doesn't it supply air to the oil injectors?

any cat needs the air pump, cats like to see 14.7:1 mixture and the air pump adds air to the exhaust at idle and low speeds to acomplish this, without the air pump its too rich for the cat to live

how does the air get into the exhaust? is it through the ACV then through the channels in the rotor housings?



and, do the oil injectors need air from the air pump as well?

The acv pushes air from the airpump through the split air tube to the cat. There should be a long pipe going to the cat.

Just curious, i have been running a straight pipe on my s5 for a while, didnt realize that the cat operated the 5,6 ports.. What exactly is the VDI and is there anything I can do to work around it? I have been debating wiring the 5,6 ports open since i understand they havnt been operational since i put in the straight pipe i guess.. Thanks guys.

S5 doesn't run that way, S4 works off back pressure. In an S5 you should be fine as long as the air pump and acv are working.

Good stuff, so is there actually any of the ratsnest I can actually remove or just leave it?

There are, but I am not up to speed on all the details so I don't want to steer you in the wrong direction.

hey guys i have a quick question. Im new to here and all i have a black 89 gtus with 64k orig. miles. It has race beat full exhaust with the race header. I need to know about the air pump thing i just put a small breather on the hose that went into the air box when i removed the air box system and put a nice new cone filter on the end of the maf. Is that ok just to put a small air breather on the fairly large hose that went into the air box. thanks for your help and i love mazda and my new rx7.

so i guess i need to put the air pump back on.

so i have a question. im doing a turbo swap into my na its a 89 with a s5 turbo engine. 2 things does anyone have a picture of the egr removed with a block off plate. second and this may sound dumb but were does the vacum line for the blow off valve go. one more question. were does the vacum line from the pressure sensor go on a turbo engine. thank you

huh i figured it out. makes since the blow off valve vacum line goes to the pressure sensor. but i saw that there is a t-joint going from the air control valve. so i was gonna block off the acv with a block off plate. sould i leave the acv on or just run a line straight from the blow off valve to the pressure sensor?

Re: Airpump Removal
 

So the air pump on 86 fc stopped working. The main cat attached to the air pump rusted off. So I had a test pipe welded. My question is what do I need to do to have my other ports open?