Header/Exhaust O2 sensors
 

Hi all...
First off wanted to say your forum is great and very informative.
My question is regarding the O2 sensors before and after the first cat. Ideally I would like to Install a HP header which (maybe) will remove the first cat, from there I would like to have the bosal catback (federal) which would remove the second cat. The emmisions is not an issue for me cause it is currently not tested in Fl. Does this setup sound possible and if so how will I tackle the issue of the 2 O2 sensors. That is where I am stumped. I dont know how I would be able to get different readings with this setup in order to keep the check engine light off.
If I wouldnt be able to work it with this setup how about a HP header with a Bosal Cali exhaust with the second O2 sensor behind the cat on the exhaust. Would this give me enough of a different reading to keep the main comp happy? I am still rather new at this P5 stuff and I am only going on the info I have read on the exhaust threads here at PC forum. I am up for any suggestions... I would just like to get rid of all this restricting ULEV crap without having to rip everything apart like travelers project. Thanks in advance for all your help :-D

The stock primary cat is definately a restriction. I tore my exhaust apart, measured everything and did some mods from the #2 cat forward. See 'exhaust measurements' for a list. If you eliminate the primary cat, you might be able to put an extension on the 2nd O2 sensor wires and put the O2 sensor behind the #2 cat. I haven't tried this yet since my system retains both the sensors in the factory location. If I get a header, I'll move them and try it out. I'm really noticing a difference in power with the mods I did. I'm putting it on a dyno on Tuesday at 9:00 AM (PST) to see what it's actually putting to the wheels.

Well, I'm not sure if this is the solution but, this may work. If the engine throws a code with the described setup, I *THINK* it will be a CEL code, which has something to do with cat conver inefficiency. The product the guys on www.i-club.com (subaru forum) use is called the *MIL eliminator*. It basically wires into the second O2 sensor to mimick the proper readings for the ecu not to throw a code.


Here's some info and the place that sells 'em from i-club:


WRX Cat inefficient CEL Fix (Mil Eliminator)
Recently I installed the Mil Eliminator available from Pony Express Performance. I finally had enough of the P0420 Catalyst system efficiency below threshold CEL I was looking at every day due to my off-road set-up (catless Scoobysport and Vishnu Uppipe).

Installation was pretty straightforward. I disconnected the rear O2 sensor leads from the harness and unclipped it from the two frame mounting points. I removed the sensor from the exhaust system, 'cause I didn't want to try soldering upside down Once off of the car wiring in the Mil Eliminator was pretty simple. The instructions are easy to follow. The vendor recommends soldering or using butt connectors. I used a bit of heat shrink tubing at the four points where I spliced in the Mil Eliminator about two inches from the connector. After wrapping the area real well with electrical tape (I intend to improve that later) I re-installed the O2 sensor.

It's been on the car now for a little over a week and a half. I've driven 560 Cat inefficient CEL free miles. Without the MilEliminator I would expect the CEL to pop on within the first 30 miles of clearing the code. I'm pretty convinced that particular CEL is something I won't be looking at in my car again.

Dan at Pony Express Performance was extremely helpful and answered all of my questions prior to ordering and installing the device. You can contact him through the website.

If you decide to order the Mil Eliminator it will run you $20.95 including standard shipping. Is it worth it? That's entirely up to you as the consumer. It certainly is to me. I have no idea nor do I care how inexpensive the components are. I paid for a proven product from a vendor that offered me a guarantee and has the product ready to go.

The item you want is the PEP-SMIL. Be sure to indicate in the notes section that you are ordering for a WRX otherwise you might receive a set of instructions for a Mustang

Do a search
 

The wiring diagram on how to make your own MIL eliminator is here somewhere.

Re: Do a search
 

lol, when you search for that word, or any combinantion the only thread that comes up this one. So I would like more info on this too, I searched the web and I can only find them for WRX's and Mustang's so far.

Thanks for the good info :-D
Yeah travel I read your whole thread... NICE WORK ;)
I would go about it your way but I dont currently have the resources to do so. So I am trying to go about it a different route with aftermarket parts.
Now I have to bring up another question. Does anyone who has some info on the HP headers know if there is going to be an 02 sensor bung? and for all those folks who have the Bosal (federal) cat back does that have an 02 bung? If not is there a way to make my own?
Thanks for the Mil eliminator idea. have never heard of it... that will be more then likely the way to go. Only logical solution so far hehe :-D thanks again for the info... you all rock!

So the Mil eliminator wont work for the P5?????

I got the Bosal catbcak and it goes on with no issues, or any messing with any O2 sensors. The sensors are are up at the exhaust manifold and right past the primary cat (at least I'm pretty sure that's what I saw when I was sticking my exhaust on)

Thats right the O2 sensors are before and directly after the first cat and the Bosal federal only removes the second cat right? The HP racing header is said to remove the first cat as well. So with the HP header and Bosal cat I will have no cats whatsoever... right??? Please correct me if I am wrong. But back to the main question with this setup HP/bosal how will I be able to tackle the O2 sensors issue??? Would I be able to maybe get the Bosal cat back (Cali) system which has a cat and put the first 02 sensor on the header and the second after the cat on the bosal exhaust. Would this be a logical solution? Just spitting out ideas. ;)

Yeah I dunno dude. I'm in just about the same boat as you. I really wanna get that HP header as well to feed my Bosal a less restricted flow. But I'm not real knowledgable about the headers or the O2 sensors either. We need some experience here. Help please.

Youre right sweeden... I have to find any info on the Mil eliminator for the MP5. anyone got the link to the thread were it explains how to make your own????
This maybe the answer to our prayers sweeden :)

Oh by the way anyone know the ass who decided to engineer this ULEV shit. I want to track him down and give him a swift kick to the junk. :D

This is exactly what I have been trying to mention on the board for the last little while. Go with the cali version of the bosal (or for that matter almost all other cat-backs being sold for us leave the 2nd cat in). Then go with a new header (whomever comes first).
What we now need is someone to build is a high-flow cat, with 2 o2 bungs to tie our o2 sensors in. It should not be too hard, since the mid-piece that contains the 2nd cat is bolted. Best would be ifd it was sized to match the larget than stock id of the bosal (slightly larger only).
I hear maybe protege5online may be thinking about getting some made. I imagine he will wait to see if there is enough interest.

Sorry tester I hadnt seen any of your threads...
So their is no way I could get the federal bosal version to work... even with a Mil-eliminator???
Correct me if I am wrong but wouldnt a system with no cats flow better then a system with??? Although I shouldnt be so picky hehe a high flow cat system will work for me at this point. ;)
If Protege5online is wanting to do this count me in... the check will be in the mail tommorow if need be :D
Also kudos to Pro5online and PC forum... you all rock. Thanks for the info sources guys I would be dead in the water otherwise!

Nick

MIL Eliminator
 

Remove your second O2 sensor and modify the wiring on it like shown below. Only do it to the second sensor. Do it to the first and you're gonna melt a piston.
http://personal.bellsouth.net/mia/c/...r%20Wiring.jpg

Thats It????
 

Damn I thought it would be alot more then that... So just one resister and one cap? I guess that would be enough to change the current. Has this been tested and proven???

Also what did you draw that schematic up with???
Electronics workbench? or did you find that on the web???

Thanks bro,
Nick