pinksock Posted January 20, 2011 Share Posted January 20, 2011 Hey guys got a question for u. I own an 85 GL wagon with the ej22 in it, my buddy who owns a suby dealership just gave me some little headers for the ej motor that came off a jap version suby. So my question is, i want to put custom true dual exhaust on it n still not throw any codes n have her run right. So is it possible to splice together the wiring from two cats (which I have) so the motor runs right. Let me just add I'm a welded by trade, work in a huge shop where I have access to any tool I need, so I'm open to any suggestions to make this work. I don't know if I'm even thinking about this the right way. I'll b making the exhaust completely from scratch all the way down to my own mufflers. But any way, suggestions on how to run 2 cats successfully? Oh p.s. live in Idaho we have emission laws so it has to have cats or I can't register it every year. thanks Quote Link to comment Share on other sites More sharing options...
MilesFox Posted January 20, 2011 Share Posted January 20, 2011 Make a x-type arrangement with a pair of cats as the collecotor, then back out to duals Otherwise, make an x-style pioe with one cat as a collecotr, and fool the 2nd o2 sensor with a resistor. If you had no cats, you can use anti-foulers in the o2 bung to move the sensor out of the exhaust stream. You should take a look at the car's ORIGINAL y pioe for some idea Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 20, 2011 Share Posted January 20, 2011 Short answer - no. The computer has only a single O2 sensor that controls mixture. It has to be installed in the exhaust stream of all 4 cylinders. Thus you cannot operate a *true* dual exhaust and have the computer work correctly. An H pipe will not work for the same reason - you are not getting a true sample because the flow can bypass the sensor. It MUST go to a collector first where the sensor can sample the exhaust stream and THEN you can run two pipes out the back if you want. There's no benefit to it though. GD Quote Link to comment Share on other sites More sharing options...
pinksock Posted January 20, 2011 Author Share Posted January 20, 2011 Ok so what if I were to run two cats on each side after the headers n welded the O2 senser holes closed n ran those into a X pipe where I could put a new bung for one O2 senser so it was reading the exhaust stream from both side then run dauls out back. I want to run an X pipe anyway because it equalizes back pressure n u get a better exhaust tone. Right now I'm running my car with just the y pipe on, no mufflers n I like the deep sound I get I don't want to loss that sound. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 20, 2011 Share Posted January 20, 2011 Nope - the cat's destroy the information used by the O2 sensor. The sensor MUST be about 12" to 24" from the heads (for temperature reasons) at a collector point. You cannot put anything in the pipe before the O2. Period. Of course - if you want to run some other form of engine management then you are free to do whatever you like. But within the constraints of the stock ECU - it will not do what you want. GD Quote Link to comment Share on other sites More sharing options...
pinksock Posted January 20, 2011 Author Share Posted January 20, 2011 So let me ask u this. What if I where to knock out the baffling in the cats so they where hollow n their just for emission laws n nothing else n where able to put n X in the pipe after the hollowed out cats but within 24inches of the headers, would the O2 senser work then if it was in the X pipe then? Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 20, 2011 Share Posted January 20, 2011 Only if you opened the cats and installed a pipe inside them. The large cavity of the cat will create a "stall" in the flow velocity of the exhaust - that will cause issues with the feedback from the O2 sensors - they will not get a consistently timed exhaust flow through the entire RPM band. It's a bad idea. Though you could get cat's that have larger pipe openeings than you need, gut them, and then run a pipe straight through them. So the point is for a visual inspection requirement? Why not put a single cat after the collector like the stock exhaust? GD Quote Link to comment Share on other sites More sharing options...
MilesFox Posted January 20, 2011 Share Posted January 20, 2011 make the exhaust an x shape, crossing over at the same location as the original cat on the ea82, and put your sensor right on the X Quote Link to comment Share on other sites More sharing options...
rumblee Posted January 21, 2011 Share Posted January 21, 2011 Why not just run 2 stock sized or maybe wrx cats? A single cat can flow enough for stock power levels....so two should be able to move plenty of exhaust if you're worried about them robbing power. If you're going to run dual exhaust at stock power levels you won't need large diameter piping either. I don't know what your emission tests are like in idaho but if they do a visual inspection they can fail you just by having an obviously modified exhaust system. If they just do the sniffer in the tailpipe well...my wrx passed with no cats and they are notorious for running rich. Different car but still something to think about. Quote Link to comment Share on other sites More sharing options...
Numbchux Posted January 21, 2011 Share Posted January 21, 2011 Check out my post in your other thread.... Quote Link to comment Share on other sites More sharing options...
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