drgonzo86gxl

i just bought an 86 gxl. it has a full exhaust from headers back. there are NO cat alytic converters, it is very loud so i am going to buy a the main cat this week. i see that there is an air line coming out of the cat which i believe is a vaccume line. the previous owner made a makeshift valve to bypass that line when he took the cat off.. i have looked at the shop manual and i have a good idea where the lines will go after i hook up the cat, but the problem is i do not have the lines or hoses or whatever i need that will go from the cat, to the air check. i do not know anything about this air line or vaccume line, whatever it is, if someone could help describe to me what this is for, where i can get these lines, where they go, what they are called? The car is running fine with the way that last owner rigged it up but i guess my valves arnt opening all the way because this line is not hooked up.
i have pics of the way it is rigged now, but i cannot upload them they r too large, i could email them if it could help someone help me.
im sorry i cant be any more specific since i do not understand this very well.

87rx7girl

the air tube coming off of the catalitic converter is for n/a 5th and 6th port actuator. it goes up to the engine bay. connects to a one way valve. it then attaches to the lower intake manafold. on an s4 this tube sends back pressure from the exhasut to the actuators that open and close the 5th and 6th port after 3k rpm. if you do not have this part hooked up correctly or you have an after market exhasut, you should do some research about wireing open the ports.
i like mine closed. i like to keep my low end torque. if you wire them open you'll loose a lil bit of low end torque but you will gain back your top end.

research 5th and 6th port actuator.

drgonzo86gxl

ok i did know that that pressure opened up my 5th and 6th ports but i did not know what it was called. OK. I would like to have them open up after 3k like they are supposed to. where should i research this or try to find parts? u have been very helpfull alreay i appreciate it very very much

87rx7girl

there is a mod you can do . you need a switch that is RPM sensitive. and you buy a air pump for a fish tank. and a switch that turns something on at a certian rpm. i have no idea where the info is.
thats all i know.
try searching for 5th 6th port mod
good luck

drgonzo86gxl

do you know how to wire up the 5th and 6th ports. that idea u have with the fishtank deals, i believe how that is rigged up now, but i am not getting them open all the way i believe

i want to wire them open all the way but i do not know how, any ideas where that info might be?

J-Rat

iTrader: (2)

That tube will also supply air to the cat. Its called the Split Air tube, and it has two functions, not one.

Rat

87rx7girl

really?
i didnt think supling air to the cat was a nessasary thing. but i guess for emissions perposes... it makes sence.
wierd.

HAILERS

The Split Air Pipe is shown in the free online FSM. Jpg attached.

You need a working airpump and ACV to go with any catalytic converter you install or it'll burn up/clog up in a very short period of time and your money will have been wasted.

The Split Air Pipe has a round checkvalve as shown in the attached jpg. ON that end of the pipe will be a rubber hose that attaches to the back of the intake manifold. Air from the ACV is routed to that rubber hose.

Part of the air from the ACV goes to the sleeves inside the rotor exaust ports and some air is sent to that Split Air Pipe. At other times most all the air from the ACV is dumped into the right front fenders silencer.

IN the jpg attached is the letter A circled. The A is poiinting to the split air pipe and the area where there is and approx 1/8" tube. A hose goes on that small tube and the other end of the hose goes to the feed pipe for the auxillary ports. That feed line is located just aft of the rear aux actuator. Look for it.

drgonzo86gxl

ok ty very much. i may go with just no cat and wiring open my 5th and 6th ports to see just how that works. Any info on how to do that would be appreciated, i searched for how to wire open 5th and 6th ports but i cant find anyone that has an illustraded description, or a deswcription i can understand. u have all been very helpfull already

J-Rat

iTrader: (2)

It supplies fresh oxygen to light the cat off.

drgonzo86gxl

i understand how wiring them open will work, im just a newb and dont know where they are or how to go about doing it on my own without insruction

88GXLJoe

After reading every post on the subject of opening the 5th and 6th ports, and not finding the "one" good way, I broke down and bought the racing beat downpipe/presilencer combo. With three new hangers, it ran me 367 bucks. Not cheap, but definitly worth it. Quality material, easy directions, and I am very happy with both the sound and having working ports. I havent had time to dig into them other than to test that they are now working with the dab of grease trick and the feel just before 4K.

If your looking for an easy soloution, and have the dough, I would strongly recomend this path.

This is a great community, and I thank all the people that make it the way it is.

Thank you,

Joe

Edit...if you do go this way...order the double alt pully at the same time...costs 20 bucks from a couple of vendors on this site...you will want it.

BOFHMike

I'll try to liven this topic back up... Prior owner of my fc did something odd w/ the cat and had the split air tube connected with rubber hoses and hose clamps. I can't imagin this was proper sine just today the rubber caught fire and the tube dropped from the cat. (I don't have pictures of the fire, but I will post aftermath photos in my gallery soon.) I suspect this tube is suposed to be one peice from the car to the engine compartment. Is there any way to "patch"/reattach this tube, or do I ned to replace the cat? I've looked around for replacement cats, but all the ones I'm finding photos of either don't show the tube (performance models) or show only 4 inces of tube.

arghx

iTrader: (3)

the split air pipe can be MIG welded, take it to a good muffler shop (not a national chain)

BOFHMike

I took a look at the end of the pipe, seems in good shape. (not rotted/rusted) BUT, unless I missed them (just looked under the car, didn't lift it) It looks like the two pre-cats are missing. Is there any logical reason to have removed them? How much more HP could it produce if the prior owner wasn't willing to run the car over 2400 RPM?

Toxindude

If you haven't solved this problem by now you kind find all kinds of parts at apexautoparts.net I have bought several parts from them. They will have most of the parts you need even a stock converter if you need it.

BOFHMike

Thanks for the tip... I've been getting some odds and ends from apex, but had not thought about getting the cats from them.

BOFHMike

Finally had the split-air tube welded at my local mecanic shop. Best $25 I've spent on the RX thus far.