Hi,

I have a 2004 cavalier and planning to do the full exhaust later this month. If I remove the cat, will I get error codes with the sensor plug in the new 2¼ inch pipe. Does any of you had problems with the removal of the cat. I know there are 'sensor bypass' or some kind of part like that, are they good and what exacly do I need. Is it better to use a hi-flow cat to prevent problems? I did search the board but didn't find what I need.

thanks a lot.

I went the hi flow cat route, for reason i care not to explain, I drove around for a few hours without the rear 02 sensor. The idle is rough, and it doesn't perform as well as it should. I have no idea about the bypass, but you'll definately need at least one.



http://www.cardomain.com/ride/2265283

I will plug the sensor back but not in a cat but in the pipe. By the way is there another sensor beside the one in the cat?

In short, you WILL eventually get a code. P0402 is the code I got if I remember correctly, and the car will run like garbage. The "sensor bypass" you mean is an O2 Simulator. I'm currently using the O2 Sim on my Cav, and it does get rid of the code, and the car no longer runs poorly, but it does feel a bit "limp" for just a split second when you smash the gas down.

If you're just removing the Cat and replacing it with a straight section of pipe, leaving no place to plug your O2 Sensor in, the car will run horribly, and the O2 Simulator is a must. Or if you're replacing it with a section of pipe that does have a bung to put the sensor in, you won't be as bad off, but still get a code.

Honestly, there was absolutely no advantage in my removing my Cat since I'm not turbo/supercharged, so I'll recommend to you what I plan to do. I'm getting the Magnaflow OBD-2 high-flow Converter, part # 94035. That part number is VERY important, since the 94XXX series are the only converters that won't throw codes. 94035 is the 2.25' in/out you'll want. It will keep you legal, won't throw codes, probably sound better than just a straight pipe, won't impact performance, and you won't need the stupid O2 Simulator.

You can get it at places like summitracing.com, hottexhaust.com, and justmagnaflow.com.

Hope this helped.

bleco04 . wrote:I will plug the sensor back but not in a cat but in the pipe. By the way is there another sensor beside the one in the cat?

There are 2 sensors in your exhaust. The first is located in your exhaust manifold (up in the engine bay), and the second one is the one in your converter.

thanks a lot for your help!

I was planning to plug it back in a straight pipe with a standard sensor adapter but I think I will buy that magnaflow you're talking about. But I still think it will affect the performance. I once had a civic hatch with B18B engine an running a straight pipe. When I installed the Hi-flow cat (got arrested for loud exhaust) I really felt the difference in high rpm. We will see, I will test it soon when the drags open (I live in Québec Canada).

i wouldn't waist the money on a cat it won't make u faster or make more power and from the point that u put it in its only going to get more and more restrictive the older it gets. there are only two companys in the world that make cats so the stuff in your "high flow cat " won't be any different from the one in your car the only thing that makes a cat a high flow is the case its in. a cat is not designer to benefit your car in anyway its for the environment and thats it. now granted if u can't make the computer happy there is no point in removing it because the car will go into limp mode and u will loose power just get a o2 sim and be done with it. remember the sensor in the manifold reads air / fuel make sure it remains untouched the sensor after the cat compares readings to the front one and when there is a big diff. it puts the light on and puts the computer into limp mode so u will go to the dealership and get it fixed. the o2 sim replaces the rear

LD9 Fury (The JBO Viking), can I ask you why the 94XXX series is the only one that wont throw codes? Currently I have a 91035, and Im having a code 04020 something about the catalyst not performing to efficiency level. Anyway, I called magnaflow and they suggested I buy something from the 53XXX series and it does say its for small displacement engines. Probably gonna end up sending the 91 back and hoping they give me a refund and get try another one. Thanks for any info.

I think RKSport has some O2 simulators


Some times the best way to get that tailgater off your but is to light a fart.

i have the magnaflow 94035 i felt the difference on the car after i change the catalytic converter. you can fell the higher flow that goes through the exaust. the only problem i got is that i have 2.5' as catback and im not boosted (no turbo or SC) so i had to put the silencer to the "fart can" lol so i can have pressure on the back.
it was so loud after i change the catalytic that i had to put another resonator (2 15'-16' resonators) to quite down the car. (so freaking loud that it seems it was going to break the windows) that how loud it was.

I did a global search on the internet and didn't find any o2 simulator for 2003 and up. So if nobody knows a brand of o2 sim that is fully compatible with ecotec I will buy that 'hi-flow' cat. The exhaust will be done at the end of april so feel free to suggest any solution for replacing cat.

thanks

people had issues with those simulators. I still have a cat on my 2.5" setup.


2004 Grand Prix GTP (Competition Group)
SOLD-->1999 Z24 5M-#30 to register on JBO
"You can please some of the people some of the time but you can't please all the people'
all the time

Matt wrote:LD9 Fury (The JBO Viking), can I ask you why the 94XXX series is the only one that wont throw codes? Currently I have a 91035, and Im having a code 04020 something about the catalyst not performing to efficiency level. Anyway, I called magnaflow and they suggested I buy something from the 53XXX series and it does say its for small displacement engines. Probably gonna end up sending the 91 back and hoping they give me a refund and get try another one. Thanks for any info.

That's actually a question I couldn't answer very accurately. Someone else will definitely know.