NO rear O2 sensor

[honesT]

Hey Fellow Jeepers, I have a 1996 XJ Country and the exhaust system passed air care with flying colors but the pipe below header flange has a huge dent in it and the muffler is so rusty I can probably poke my finger through it. The cat looks ok.

The reason for this post is I bought a second hand exhaust system from a 93 XJ that had a stroker engine The exhaust system is 2.5 & only 2 years old and has a High flow cat and high flow K2 muffler but the cat has no O2 sensor and my 1996 has the rear O2 sensor in the rear of the stock cat...

Should I just cut off the high flow cat and put on my stock cat and count my blessings or is there a way that won`t throw everything out of wack ?

I have read about the O2 sim cel fix http://www.bigdaddiesgarage.com/?gclid=CJOMh9-bn6UCFQUSbAodgFXBIA And the black box but it won`t give accurate enough reads as posted here http://reviews.ebay.com/Truth-about-O2-simulators_W0QQugidZ10000000002812356

Alot of info crammed in that article and it will take me a few more reads before I can comprehend it so anyone with this type of expertise or experience your time is appreciated and thanks in advance for your reply :thumbsup:

[bigjim350]

Well the easiest thing to do would to just re-use your old cat.

[honesT]

I`m not sure if puting the rear O2 sensor just behind the cat will give the same readings as the in cat sensor I had now idea the system was so sensitive to little changes, will the sensor be off due to the high flow?

[bigjim350]

Well If you have the time and money to play around I can tell you what I would do. I would remove the cat completely. Then have a new straight pipe welded to you muffler. then have an o2 sensor bung welded into the pipe where the cat would be. Then use the spark plug fouler trick to the o2 sensor, then screw it in plug it in and see what happens.

[JENSSEN]

Drill the new exhaust and weld in or have someone weld in a new o2 sensor bung post cat, high flow or standard a cat "should" do the same thing to your emissions set up. If you find this does not work run a o2 jumper pig tail that ties to the pre cat o2 and plugs into the sensor plug for the post cat o2 and lies to the computer telling it the cat is there or functioning even if it's not there or the sensor is gone, most speed shops sell these. You do need the o2 to keep the ECM tuning to rich/lean situations post cat. I can give you more info if need be

[ice_cold]

Drill the new exhaust and weld in or have someone weld in a new o2 sensor bung post cat, high flow or standard a cat "should" do the same thing to your emissions set up. If you find this does not work run a o2 jumper pig tail that ties to the pre cat o2 and plugs into the sensor plug for the post cat o2 and lies to the computer telling it the cat is there or functioning even if it's not there or the sensor is gone, most speed shops sell these. You do need the o2 to keep the ECM tuning to rich/lean situations post cat. I can give you more info if need be

So then you can remove the cat and put the pigtail from front to rear O2?
Looks like something I will look into, as my cat is fried from all the coolant that has been dumped down the pipe. Dont have the coin for a new cat right now.

[JENSSEN]

You leave the front o2 sensor in, the dummy o2 sensor runs off the front o2 and then tells the computer what it wants to see from the rear o2 sensor

[4.3LXJ]

Drill the new exhaust and weld in or have someone weld in a new o2 sensor bung post cat, high flow or standard a cat "should" do the same thing to your emissions set up. If you find this does not work run a o2 jumper pig tail that ties to the pre cat o2 and plugs into the sensor plug for the post cat o2 and lies to the computer telling it the cat is there or functioning even if it's not there or the sensor is gone, most speed shops sell these. You do need the o2 to keep the ECM tuning to rich/lean situations post cat. I can give you more info if need be

X2:thumbsup: O2 sensor bungs are not expensive

[ice_cold]

So where can I find one of these "pig tails"?
Preference in Canada

[JENSSEN]

Mopac? Your in the Northern Alberta area right?

[ice_cold]

yep yep...Mopac is just down the road from work

[JENSSEN]

Give them a shout if you have issues PM me and I will track one down,.. or just weld in bung #2

[honesT]

Drill the new exhaust and weld in or have someone weld in a new o2 sensor bung post cat, high flow or standard a cat "should" do the same thing to your emissions set up. If you find this does not work run a o2 jumper pig tail that ties to the pre cat o2 and plugs into the sensor plug for the post cat o2 and lies to the computer telling it the cat is there or functioning even if it's not there or the sensor is gone, most speed shops sell these. You do need the o2 to keep the ECM tuning to rich/lean situations post cat. I can give you more info if need be

Thanks for the info,
From what I can gather the o2 sensor heats up and cools down depending on the amount of oxygen in the system and sends this onfo to the ECU that in turn adjusts the rich and lean fuel mixture... My question is that will the 2.5 pipes and highflow cat & exhaust create more friction over the sensor messing up the readings or can I go ahead and use the stock O2 senor and have no worries. :stars: So many conflicting articles on the net to many f$%^8 ing money grubbers messing everything up for everybody as usual :boohoo:

[honesT]

This is just one good point I got from the truth about o2 sensors link I posted on my original post:

One method is to measure the signal strength of the downstream sensor. As the oxygen content of the exhaust goes down, the voltage of the O2 sensor goes up. This voltage is generated by the sensor itself. So on a functioning converter, the downstream voltage should be at least a certain amount, typically 0.4 - 0.6 volts or higher. O2 simulators do not accurately replicate this voltage level.

Another method is to measure response time. The response time method is based upon the oxygen storage capacity of a functioning converter. The vehicle will occasionally switch to a rich or lean phase for a slightly prolonged interval, and measure the amount of time it takes for the rear sensor to mirror the change.
If the signal is consistently outside specifications, the computer will set a catalyst related code, and the CEL will illuminate. O2 simulators can sometimes produce a sufficient signal delay, but this is a matter of luck

[honesT]

As per the haynes manual:
The oxygen ( O2 ) sensor is located in the exhaust manifold down pipe. It provides a varible voltage signal (about 0 to 1 volt ) to the computer, based on the oxygen content in the exhaust. The computer uses this information to determine whether or not the fuel/air mixture needs to be altered by adjusting the pulse width of the fuel injectors...

[huntingfinatic]

Here's a Questions somewhat relative..... I stripped the threads on the bung for my downstream O 2 sensor. I need to weld on a new bung. I was thinkin about grinding down the bung that is there and then welding the new one on top of the old one. If the sensor is out of the "stream of exhaust" a 1/4" or more... would that cause CEL codes to come up? I would think that any exhaust shop should have a bung I could buy and weld on....?

[4.3LXJ]

An exhaust shop should have them. If not, Summit Racing has them.