gmantibby

Got obx 4-2-1 headers and they hit my trans mount so I am having a friend cut, weld and extend the 2 pipes. I was wondering if I should attach the cat to the header and the flex to the out of the cat? Or attach the cat to the flex and put a o2 bung in the mid pipe? I need to do this without getting a CEL or I will fail inspection plus I hate that damn orange light. Sorry if this has been posted before but I need exact inst. on doing this because money is a factor and I can only afford to do this once. How do you extend the o2 wires crimp or solder? I hear solder is bad. Also heard the 2ond o2 shouldn't be moved to far because the ecu knows ex. speed and how long it takes ex to get for 1st to 2ond sensor. Read about it on the magna flow web site. Thinking of using a magnaflow or Random tech cat any suggestions?? Thanks, NEWB

'treezy

yoru OBX headers should have come with an O2 bung in one of the headers (far right when looking at them installed).

The first o2 sensor must go in this hole. I did not need to extend these wires as they are long enough to reach through the engine bay area. It may not look like it but the first o2 wires share a wire loom (or electrical tape rather) with other wires so if you undo the electrical tape binding them together you can extend the wires and sensor up into the engine bay (from behind the intake manifold) around the block (right side) and into the o2 bung. zip-tie it up nice or somethign so the wires are not touching any hot surfaces.

Someone else will have to help you with the second sensor as I took the easy way out. (but most people do not agree).

I know you have to have it after the cat but the flex pipe w/ the OBX headers probably has a bung in it. You will need to plug that bung and make a new bung (involves welding) in the piping after the cat. These wires wil need extending (just get four wires and 8 crimps and some electrical tape (no soldering). Zip tie these wires and their extension as well,. so they don't touch piping.

If wires touch piping and get too hot you'll most lekely get CEL.

You'll get CEL with OBX headers because the ECU will soon find out (after a days driving) that the amount of air being read by the first o2 sensor is not normal (it's 1/4 the normal amount since it's only in one header) and will throw that orange CEL in your face. It will think only one header is working and the others are clogged or somethign like that. I reset my ECu plenty of times with no luck so i guess I'm stuck with this CEL unless I move first 02 sensor. You will most likely have this problem too if your headers are OBX.

-patrick

gmantibby

<div class='quotetop'>QUOTE (Patreezy @ Apr 21 2005, 04:39 PM)</div><div class='quotemain'>yoru OBX headers should have come with an O2 bung in one of the headers (far right when looking at them installed).

The first o2 sensor must go in this hole. I did not need to extend these wires as they are long enough to reach through the engine bay area. It may not look like it but the first o2 wires share a wire loom (or electrical tape rather) with other wires so if you undo the electrical tape binding them together you can extend the wires and sensor up into the engine bay (from behind the intake manifold) around the block (right side) and into the o2 bung. zip-tie it up nice or somethign so the wires are not touching any hot surfaces.

Someone else will have to help you with the second sensor as I took the easy way out. (but most people do not agree).

I know you have to have it after the cat but the flex pipe w/ the OBX headers probably has a bung in it. You will need to plug that bung and make a new bung (involves welding) in the piping after the cat. These wires wil need extending (just get four wires and 8 crimps and some electrical tape (no soldering). Zip tie these wires and their extension as well,. so they don't touch piping.

If wires touch piping and get too hot you'll most lekely get CEL.

You'll get CEL with OBX headers because the ECU will soon find out (after a days driving) that the amount of air being read by the first o2 sensor is not normal (it's 1/4 the normal amount since it's only in one header) and will throw that orange CEL in your face. It will think only one header is working and the others are clogged or somethign like that. I reset my ECu plenty of times with no luck so i guess I'm stuck with this CEL unless I move first 02 sensor. You will most likely have this problem too if your headers are OBX.

-patrick
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Thanks not what I really wanted to hear. Are you sure the cel is because of the loc of the 1st O2?? could ur O2 be bad? Trying to return this if a cel is unavoidable. Pa says cel no insp sticker

REDZMAN

Please don't quote the person above you.

a_gut

Why don't you go through inspection with your stocker stuff on, and install the obx headers after?

Mad-Machine

well.. as you are going through all this trouble to extend the pipes of the header already.. why not have a bung welded into one of the secondary pipes (this is a tri-Y, or four into two into one design, right?). That will at least double the amount of exhaust flow past the sensor. If you are running a four into one.. just place it in the collector.

'treezy

yes, I'm sure my o2's are fine. Sorry if it's not what you wanted to hear but it's life. I have an OBDII reader that tells me exactly what the problem is and the code. It explained the problem above in simpler terms, saying that the ECU was only reading o2 numbers of Eg from one combustion chamber (i.e. one header). That IS the problem.

I would suggest what he said above me and keep your stock headers, downpipe and cat for inspection and OBDII law reasons.

If you have available welder (or yourself) you could try plugging the o2 bung in the header and placing the first o2 in a new bung where the headers come into one (assuming they're 4-2-1). It may be kinda hard as there is not a lot of room to weld a bung.

Then plug the bung in the OBX flex pipe, connect cat (or hi-flow cat which is what I'd recommend) and then weld another o2 bung after cat in tubing. Extend 2nd sensor to this bung and I believe this will not yeild a CEL. Who knows...

-patrick

gmantibby

Thanks, wish I had a scanner. Starting to sound like its not worth the 7-10 hp. Mabey I will try a mod that doesn't f w/ the ecu. Mabey the air ram intake twice the $ but twice the hp and no ecu bs as far as I know Don't have the $ to spend if I do all this and still get a cel. I don't want to have to keep switching parts for insp and I really hate that cel staring at me like it's better then me.Thanks for all the help I'll let you all know what I do. You all Rock. Peace, George

turbulence

i have the obx headers and had a bung welded in after the 2-1 collector so the o2 sensor would read all 4 cylinders. if you extend the wires, you run the risk of the o2 reading getting all messed up because the voltage won't work across the extended distance...at least i ran into that problem. so now i resoldered the wires, and put the sensor back in the #1 runner, but like what was mentioned above, you only get 1/4 air reading, so the car still doesn't run perfectly.

hamhead

Air-Ram probably won't yield very good results without the exhaust side being fully done. What goes in must come out... the intake manifold would probably be one of the last modifications I would touch N/A.