Rice Burner Posted December 8, 2006 Share Posted December 8, 2006 Lately it seems that my 97 impreza outback sport has been getting horrible gas mileage. My wife drives it more than i do so i am not sure exactly what the mileage is. The car has 195,000 miles on it. Does anyone know if (1) it would hurt to take off my cat and put on a straight pipe. not sure if any oxygen sensors would be affected. and, (2) if that would give me a noticable increase in mileage. If anyone has taken off their cat and could tell me what the result was, would be appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
hatchsub Posted December 8, 2006 Share Posted December 8, 2006 Not sure what the regulations are in WV but up in connecticut you need the cat present to pass emmisions. My guess for you bad milage would be the O2 sensor being crapped out and possible a clogged cat. I dont think your alowed to pull the cat. Quote Link to comment Share on other sites More sharing options...
jamal Posted December 8, 2006 Share Posted December 8, 2006 if it is a trashed/clogged covertor you need to replace it. The difference in power and mileage between a good cat and a straight pipe is pretty much negligable. Not having one is incredibly irresponsible and illegal. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted December 8, 2006 Share Posted December 8, 2006 if it is a trashed/clogged covertor you need to replace it. The difference in power and mileage between a good cat and a straight pipe is pretty much negligable. Not having one is incredibly irresponsible and illegal. it's like the coach said in one of those baseball movies, "spit ball is a totally illegal pitch and i don't teach it to my pitchers, but....." Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted December 9, 2006 Share Posted December 9, 2006 Hi, whether or not it is a state or local issue, it probably violates some federal law. If at all possible you probably want to keep the front O2 sensor intact. This sensor is used for air/fuel ratio control in closed loop operation. You need to know whether all emissions devices need to be intact for inspection (if you have an inspection). In NY they are required and there can be no disabled/removed components. If you ever decide to sell the car, I would make sure to intimate that fact to the buyer. Quote Link to comment Share on other sites More sharing options...
keltik Posted December 9, 2006 Share Posted December 9, 2006 The cat on my last car was a bit smashed up thanks to some off roading. I gutted it and got a small improvement in gas mileage and top end power, however it dramatically changed the exhaust note. In the end i went to a shop and had a glass pack put in its place. In my particular case it wasnt cheaper to just go get a cat from the wreckers - but it might be an idea for you to try. That solution would also solve your problem of passing smog test or whatever (we dont have em here). Quote Link to comment Share on other sites More sharing options...
Distance Commuter Posted December 9, 2006 Share Posted December 9, 2006 Just plain old flat-out against federal law to remove or disable emissions equipment. Period. I'm old enough to remember the air on the highways and in cities before cat converters. Absolutely toxic. There are reasons we spend money putting them on our cars and they're good reasons. I also hate spending a few hundred dollars now and then to replace one of those buggers. But I do it. Quote Link to comment Share on other sites More sharing options...
Wayne Boncyk Posted December 9, 2006 Share Posted December 9, 2006 It's also illegal to sell a used cat, unless you are a certified rebuilder (need an EPA permit). I guess they're worried about an aftermarket of used hardware that no longer works -- kinda defeats the purpose of having a cat in the first place. Quote Link to comment Share on other sites More sharing options...
Seahag1978 Posted December 9, 2006 Share Posted December 9, 2006 The last time I looked, it's a federal offense that carries a MAJOR fine AND some possible imprisonment if convicted. To add insult to injury, the last I heard a federal offense also spells felony. Keep the cat... at all costs... it's cheaper. Quote Link to comment Share on other sites More sharing options...
nipper Posted December 9, 2006 Share Posted December 9, 2006 Ok lets back up here. First thing to do is to replace the front 02 sensor. You will need to replace this anyway if you have a bad cat. the 02 sensor has the most to do with gas mileage. if you were complaing of poor performance (no pickup or cant get above specific rpm) then i would blame a clogged cat. You can fail inspection (even a non emission one) by having a modified exhaust. nipper Quote Link to comment Share on other sites More sharing options...
hankosolder2 Posted December 9, 2006 Share Posted December 9, 2006 It's also illegal to sell a used cat, unless you are a certified rebuilder (need an EPA permit). I guess they're worried about an aftermarket of used hardware that no longer works -- kinda defeats the purpose of having a cat in the first place. The rationale behind the "no used cats" rule made sense back in the day, but it seems silly in the age of OBD II cars; if a used cat isn't performing correctly, it will set a check engine light & trouble code for low catalyst efficiency. So now, rather than receiving a perfectly good used cat off a wrecked car, lower value cars with bad cats tend to be sold and migrate to states without emissions inspections. (Or, here in Illinois, to counties without emissions inspections.) It's a net negative effect for the environment. Nathan Quote Link to comment Share on other sites More sharing options...
jon38iowa Posted December 9, 2006 Share Posted December 9, 2006 if it is a trashed/clogged covertor you need to replace it. The difference in power and mileage between a good cat and a straight pipe is pretty much negligable. Not having one is incredibly irresponsible and illegal. Amen! The converters made in the 70s put a strain on the drive train. The new ones made today are most negligible in their negative effects. The layer above us that protects us from the solar elements is very thin! If you doubt me, go to Nasa and ask them. I am not a green peace tree hugger,but, I do think we all should do what we can to protect are Air and Water. Most of us want to leave this world a better place for those that follow. Quote Link to comment Share on other sites More sharing options...
99lego Posted December 15, 2006 Share Posted December 15, 2006 Just plain old flat-out against federal law to remove or disable emissions equipment. Period. My county in AZ doesn't require emissions testing. The federal government doesn't exactly send drones throughout the desert checking the emmisions equipment on peoples car. And on another note carbon emissions are carbon emissions. In the form of Carbon Monoxide or Carbond Dioxide your car will emit the same weight of carbon in either form. Carbon Monoxide happens to be very toxic and cat converters chemically "change" it into carbon dioxide. Both are greenhouse gasses. Quote Link to comment Share on other sites More sharing options...
Juan Posted December 17, 2006 Share Posted December 17, 2006 Thumb suckin' hill muffins. Gut the cat (burn it out with a flame wrench) and drive it. Keep a cat handy for later and wrench it in as needed. Homeland Security is not gonna raise the terrorist threat level over your gutted cat. Juan Quote Link to comment Share on other sites More sharing options...
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