Hello fellow prelude drivers 4th gen.
i have a prelude 1993 si 2ws h23a1 engine no mods completely stock. the only non stock parts of the car is the exhaust. i have direct piping from the engine to the muffler. but i have no cat. my question can removing the cat from the equation cause the engine to malfuntion.
Can removing Cat cause engine problems
Moderators: RedRacer, spiffyguido
-
sosaprelude93
- Lude Dude
- Posts: 16
- Joined: Thu Aug 11, 2011 12:38 am
-
RedRacer
- Moderator
- Posts: 532
- Joined: Sat Nov 19, 2005 10:38 pm
- Prelude Model: 1995 Si w/mods
- Location: Alabama
Re: Can removing Cat cause engine problems
Shouldn't cause actual engine malfunction in the short term, but it's not recommended. It's there for a reason. If the car had not been engineered for and around having a cat in the system, it would be different.
Since it is an integral part of the car's emissions system, it really needs to be in place, as that system trying to compensate or correct for failures due to a removed cat, will ultimately impact the car's functionality, performance, longevity, etc.
On a long term basis however, I have heard some say it will cause no real "mechanical" problems, but I've heard others say that it can lead to eventual burned valves, faulty or malfunctioning EGR systems, etc.
Also, not to mention that it does allow harmful gases and pollutants into the air, and ya know, while I am not a huge environmentalist, I do think we should respect our planet and not deliberately or intentionally alter or remove mechanisms in place that protect our air, water and our planet. If that weighs with your conscience, then good, you know you should put the cat back on the car. If not, then it's your call........ do what you will.
Did you remove the cat or was it gone when you got the car?
This is more Spiffy's department, he's the best at the internals and causality of engine internals and externals and connected components. I'm sure he'll chime in at some point.
Me, I say put it back. But it's ultimately your call.
Since it is an integral part of the car's emissions system, it really needs to be in place, as that system trying to compensate or correct for failures due to a removed cat, will ultimately impact the car's functionality, performance, longevity, etc.
On a long term basis however, I have heard some say it will cause no real "mechanical" problems, but I've heard others say that it can lead to eventual burned valves, faulty or malfunctioning EGR systems, etc.
Also, not to mention that it does allow harmful gases and pollutants into the air, and ya know, while I am not a huge environmentalist, I do think we should respect our planet and not deliberately or intentionally alter or remove mechanisms in place that protect our air, water and our planet. If that weighs with your conscience, then good, you know you should put the cat back on the car. If not, then it's your call........ do what you will.
Did you remove the cat or was it gone when you got the car?
This is more Spiffy's department, he's the best at the internals and causality of engine internals and externals and connected components. I'm sure he'll chime in at some point.
Me, I say put it back. But it's ultimately your call.
-
sosaprelude93
- Lude Dude
- Posts: 16
- Joined: Thu Aug 11, 2011 12:38 am
Re: Can removing Cat cause engine problems
thanks for the information reracer I actually baughtt my lude that way and I know that these car come stock with a cat. But I agree on placing it back into the exhaust ultimately it can only benifit the car
-
RedRacer
- Moderator
- Posts: 532
- Joined: Sat Nov 19, 2005 10:38 pm
- Prelude Model: 1995 Si w/mods
- Location: Alabama
Re: Can removing Cat cause engine problems
I thought that I remembered in one of your posts you said it had been removed by the previous owner.
Is your (CEL) check engine light on? Cat removal with sensors left in place after removing it, can cause the check engine light to come on.
They're expensive to replace if you go with an original one -- unless you can find one at a junk yard.
Auto parts stores sell replacements for cheap, but I don't know how good they are or if they allow for the right kind of pressure and flow for your OEM exhaust, etc.
Someone got under my 93 Accord LXi and cut the cat off.... I didn't replace it because I wasn't driving the car that much. Sold it and the new owner was going to replace it, but he just drove it that way and never did that I am aware of. I don't know if he has ever done it or not. It was INCREDIBLY loud, and he never even replaced the missing section with straight pipe.... now THAT is not a good idea.
Don't worry over it and think it needs to be done tomorrow, but if you have the extra money, the time and the want, sure, put it back inline. You'll probably lose a couple of HP and you're MPG will drop a little -- just FYI.
Again, Spiffy will probably have some good input here if and when he gets the chance to read up on the posts.
Is your (CEL) check engine light on? Cat removal with sensors left in place after removing it, can cause the check engine light to come on.
They're expensive to replace if you go with an original one -- unless you can find one at a junk yard.
Auto parts stores sell replacements for cheap, but I don't know how good they are or if they allow for the right kind of pressure and flow for your OEM exhaust, etc.
Someone got under my 93 Accord LXi and cut the cat off.... I didn't replace it because I wasn't driving the car that much. Sold it and the new owner was going to replace it, but he just drove it that way and never did that I am aware of. I don't know if he has ever done it or not. It was INCREDIBLY loud, and he never even replaced the missing section with straight pipe.... now THAT is not a good idea.
Don't worry over it and think it needs to be done tomorrow, but if you have the extra money, the time and the want, sure, put it back inline. You'll probably lose a couple of HP and you're MPG will drop a little -- just FYI.
Again, Spiffy will probably have some good input here if and when he gets the chance to read up on the posts.
-
spiffyguido
- Moderator
- Posts: 2196
- Joined: Fri Nov 11, 2005 2:55 am
- Prelude Model: 1991 SE-SR
- Location: Alberta, Canada
- Contact:
Re: Can removing Cat cause engine problems
A few things:
Whether or not deleting the cat will impact the engine usually depends on the O2 sensor setup on the car. Many newer cars have sensors both infront of and behind the catalytic converter. In these cases, deleting the cat will almost always result in the computer having a hard time working out what type of fuel to meter. As RedRacer said, this won't likely cause mechanical problems, but it could certainly put strain on your other sensors and will likely impact performance negatively. Nowadays you have to remember that cars are manufactured with the catalytic converter in mind, so even if deleting the cat made sense in the muscle car era to get better exhaust flow, the same doesn't hold true today. This brings me to my second point:
Honda engines need backpressure! Never forget this. Unless you're running a turbo, the Honda engines are actually designed to run best with a slight amount of backpressure in the exhaust. Even your exhaust manifold is designed to capture the pulses coming out of each cylinder on the exhaust stroke to help maximize the quality of the fresh charge. It's all part of the engine's ability to 'scavenge' exhaust gases from the combustion chamber. I've seen plenty of people whining about how they spent a grand putting a 3" exhaust (no cat) on their Hondas and then ended up with 10 fewer HP. Your cat an exhaust piping size plays into this backpressure. Plus, the cat is there for the environment as well, which I think is worth protecting.
If you have some money to spend, there are free-flowing cats that might help a little bit. However, it's nearly impossible to say whether these would help or detract from performance. At peak RPM (and thus, peak power), I bet they may help a bit, but for daily driving, you're not going to notice it. I'd spend the money on some expensive plug wires, because that will help.
Whether or not deleting the cat will impact the engine usually depends on the O2 sensor setup on the car. Many newer cars have sensors both infront of and behind the catalytic converter. In these cases, deleting the cat will almost always result in the computer having a hard time working out what type of fuel to meter. As RedRacer said, this won't likely cause mechanical problems, but it could certainly put strain on your other sensors and will likely impact performance negatively. Nowadays you have to remember that cars are manufactured with the catalytic converter in mind, so even if deleting the cat made sense in the muscle car era to get better exhaust flow, the same doesn't hold true today. This brings me to my second point:
Honda engines need backpressure! Never forget this. Unless you're running a turbo, the Honda engines are actually designed to run best with a slight amount of backpressure in the exhaust. Even your exhaust manifold is designed to capture the pulses coming out of each cylinder on the exhaust stroke to help maximize the quality of the fresh charge. It's all part of the engine's ability to 'scavenge' exhaust gases from the combustion chamber. I've seen plenty of people whining about how they spent a grand putting a 3" exhaust (no cat) on their Hondas and then ended up with 10 fewer HP. Your cat an exhaust piping size plays into this backpressure. Plus, the cat is there for the environment as well, which I think is worth protecting.
If you have some money to spend, there are free-flowing cats that might help a little bit. However, it's nearly impossible to say whether these would help or detract from performance. At peak RPM (and thus, peak power), I bet they may help a bit, but for daily driving, you're not going to notice it. I'd spend the money on some expensive plug wires, because that will help.
