is there anyway i could bypass the after cat o2 sensor on an 03 cavalier....being as how my state doesnt have inspections or emissions testing i dont need a cat....and it seems to be that darn o2 sensor that is holding up my smog machine!
There are tools mechanics use on a diagnostic scope to test there equiptment called a signal generator. They arent that expesive and you can dial in a specific voltage or frequency.
Speed costs... How fast ya wanna go??
<a href="http://mywebpages.comcast.net/pj1987">My old cars</a>
in the past I just cut out the convertor and welded an o2 fitting on the pipe the sensor is still functioning and never had any problems
Isn't there a ghost O2 Sensor that you can buy through Highrevmotorsports.com? or am I thinking of something else.
Do a search for O2 sim. There is a $5 mod to get rid of the CEL.
FU Tuning
unless you are boosted, you need a cat and don't try and convince me any different. but if you really really need the o2 sim, you can do the DIY (search) or buy the o2 sim from RK Sport, Caspers Electronics, or Summit Racing.
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Spotabee Racing (The Fake Z24) wrote:unless you are boosted, you need a cat and don't try and convince me any different.
Really!
You don't NEED a cat. It just reduces emissions. And higher exhaust velocity= more horsepower.
If you were to look at an o2 sensor before the cat with an analog volt meter, you should get a wavy line. The after cat o2 sensor should give a straight line. If the second o2 sensor voltage varies the cat is bad or there is no cat.
Sunfires rule! (Tom) wrote:Spotabee Racing (The Fake Z24) wrote:unless you are boosted, you need a cat and don't try and convince me any different.
Really!
You don't NEED a cat. It just reduces emissions. And higher exhaust velocity= more horsepower.
If you were to look at an o2 sensor before the cat with an analog volt meter, you should get a wavy line. The after cat o2 sensor should give a straight line. If the second o2 sensor voltage varies the cat is bad or there is no cat.
on a four cylinder that is composed primarily of stock parts and on a stock PCM tune, the backpressure from the cat IS NEEDED. Look, I ran without a cat on my car for several months and off the line, it was piss slow. No backpressure does not improve gains without boost.
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well i plan on adding boost in the near future...so that is why i was inquiring about this mod
buda wrote:well i plan on adding boost in the near future...so that is why i was inquiring about this mod
In that case, don't go test pipe with o2 sim until you are boosted.
I was a retard, and now I'm permanently banned.
Spotabee Racing (The Fake Z24) wrote:Sunfires rule! (Tom) wrote:Spotabee Racing (The Fake Z24) wrote:unless you are boosted, you need a cat and don't try and convince me any different.
Really!
You don't NEED a cat. It just reduces emissions. And higher exhaust velocity= more horsepower.
If you were to look at an o2 sensor before the cat with an analog volt meter, you should get a wavy line. The after cat o2 sensor should give a straight line. If the second o2 sensor voltage varies the cat is bad or there is no cat.
on a four cylinder that is composed primarily of stock parts and on a stock PCM tune, the backpressure from the cat IS NEEDED. Look, I ran without a cat on my car for several months and off the line, it was piss slow. No backpressure does not improve gains without boost.
I'm on a stock PCM tune, also a stock internally motor. I have not cat, and yet my car will out perform most if not all N/A cars on this org with hi-flow cats and exhaust.
FU Tuning
John Higgins wrote:Spotabee Racing (The Fake Z24) wrote:Sunfires rule! (Tom) wrote:Spotabee Racing (The Fake Z24) wrote:unless you are boosted, you need a cat and don't try and convince me any different.
Really!
You don't NEED a cat. It just reduces emissions. And higher exhaust velocity= more horsepower.
If you were to look at an o2 sensor before the cat with an analog volt meter, you should get a wavy line. The after cat o2 sensor should give a straight line. If the second o2 sensor voltage varies the cat is bad or there is no cat.
on a four cylinder that is composed primarily of stock parts and on a stock PCM tune, the backpressure from the cat IS NEEDED. Look, I ran without a cat on my car for several months and off the line, it was piss slow. No backpressure does not improve gains without boost.
I'm on a stock PCM tune, also a stock internally motor. I have not cat, and yet my car will out perform most if not all N/A cars on this org with hi-flow cats and exhaust.
Why is that?
Because catalytic convertors are restrictive.
stock cats may be restrictive yes. but so are stock exhaust systems. that's what we have HIGH FLOW cats for
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A highflow cat will flow nowhere near as much as a catless car, end of discussion.
Blew it up
98redcavz24 wrote:A highflow cat will flow nowhere near as much as a catless car, end of discussion.
but even a high flow cat provides the ample amount of backpressure necessary for low end torque on a naturally aspirated four cylinder. that is my point.
I was a retard, and now I'm permanently banned.
Spotabee Racing (The Fake Z24) wrote:stock cats may be restrictive yes. but so are stock exhaust systems. that's what we have HIGH FLOW cats for
Ummm, the catalyst is still the same between high flow and not.
It's just how the piping and core are constructed.
and Most newer cars come stock with high flow cats.
and some info to read up on:
http://www.car-sound.com/04quality.asp
OK. If you guys want to run around on straight pipe, and get pulled over, and have no torque, then hey that's awesome. But when I finish my boost project, open downpipe and it's still nowhere near as loud as your 2.5" open pipe (because turbos quiet down exhaust) then we'll see who pulls harder off the line (and no, i'm not expecting spool until 3 grand... off the bottle anyways)
I was a retard, and now I'm permanently banned.
I dont see how you figure taking off the cat is going to reduce your backpressure that much and you are going to loose power. Maybe if you are taking your cat off and not running any exhaust after that. Everytime I have taken a cat off I have noticed torque gains not very much but not loose any by any means. If you are still runing a full exhaust with a muffler that is the factory size or not much bigger that will be plenty of back pressure for the motor to operate fine, and not be much louder its a little louder but not enough to get you pulled over.
I had 2.5" to 2.25" catback, with the 2.5" test pipe. The car was twice as loud, raspy, and it had ZERO low end torque. I know from experience.
I was a retard, and now I'm permanently banned.
Stock ohv's are nothing but low end torque. So I guess for those ohvs, don't remove your cat.
umm, its super illegal to not have a cat, and if you get pulled over, get ready to pay thousands of dollars in fines.
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- Sold my beloved J in April 2010 -
Why even bother with an exhaust it too is restrictive?
Go get a 100 CELL CAT.
Power Curve
100 cell cats are like chicken wire compared to a 200 cell high performance cell which would be like the holes in the screens on your house windows and doors. Boosted engines don't like or don't need any back pressure. However the naturally aspirated engine does need some backpressure and a muffler aint the ideal place to generate this.
Power Curve
its been proven over and over alot of cars will loose power from not having cats
also its been tested that older cars have gained power from ADDING cats
also even if your state doesnt have emissions its still a large fine to tamper with emissons equipment
unless your building a race only car i see no reason to get rid of the cat
also there are metal substraight cats out there that out flow ceramic bed cats
