Driving without Catalytic Converter (Illegal)

[tacks]

If a repair shop noticed that i didn't have a catalytic converter would they report me? Would they refuse to work on my car? Would i be better off using a hollowed out old cat instead of test pipe?

I live in Eastern PA. I have a 90 honda civic which has NO ricer boy engine modifiations. (It's not like a cop would suspect my car.)

My gas mileage is far below what it should be. I've read where many people w/ civics just drive the car without the cat. I'm considering driving w/out the cat. I have very little DIY mechanical skill and no tools.

Any thoughts?

(Sorry to all of you environmentally conscious folks

)

 

[Titan]

Are you thinking elimination of the cat will help your fuel efficiency? If so, better think again. ICEs are designed to operate with a specific amount of pressure in the exhaust pathway...changing that can result in worse economy. If your computer can't change it's fuel/air mixture enough, you can end up running too lean...which is too hot, which can burn holes in pistons, or other not quite so drastic damage. Just wondering why you are considering leaving it out of the exhaust pathway.

 

[tacks]

Titan,

Fourth generation civics are always faster with less back end pressure. Removing an old & gunked up cat like mine improve speed.

But actually I forgot that not everyone believes that high flow exhaust especially helps MPG of our cars.

 

[unDummy]

'90 doesn't have OBDII. If you don't care for asthmatics or the environment, you can remove the catalytic.

I've never seen a shop report anyone for not have a catalytic. But, if there are ANY emissions or safety testing in your area, you will fail.
Don't expect any shop to remove it for you.
You can easily hollow it out if you want(to pass the visual).

 

[Quest]

LOL!

So, you are one of them who takes away our carbon credits from north of 49th parallel (by chopping off emissions control), eh?!

(*too bad I can't report you because I'm in Canada*)

RE: low fuel economy, you shall look into the improper back pressure created by hollowing out your cat, engine compression checks, and what-not.

 

[Quest]

Oh I second Titan's remarks RE: ICEs.....it is indeed true (too bad our preaching usually falls into dumb/deaf ears).

After recently spending some serious time learning the basics of 2-T engine designs and calculations, it is to my knowledge that NA IC engines would require a proper balance(or compromise if you like to view it that way) between the engine and the exhaust in order to maximise output at a specific RPM (or RPM envelope).....casually hollowing out cats, sticking in cat-back 3" exhaust pipings with cherry bombs usually gets you nowhere.......

*grin*

 

[01rangerxl]

You can buy a universal cat for $60 or so and get it welded in pretty cheap. Why not just do that and keep your car legal instead of breaking the law and polluting more than you need to?

 

[Master ACiD]

Quote:

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Are you thinking elimination of the cat will help your fuel efficiency? If so, better think again. ICEs are designed to operate with a specific amount of pressure in the exhaust pathway...changing that can result in worse economy. If your computer can't change it's fuel/air mixture enough, you can end up running too lean...which is too hot, which can burn holes in pistons, or other not quite so drastic damage. Just wondering why you are considering leaving it out of the exhaust pathway.

---

ive never seen an engine minitoring device that shows the computer if there is backpressure or not. an engine cant tell the difference.

 

[rpn453]

It's not about backpressure, it's about the inertia of the exhaust flow. It is possible, but unlikely, that hollowing out the cat could make things worse. But replacing the cat with a piece of straight pipe of equal diameter to the rest of the system is definitely going to make more power and better fuel economy at all rpms by reducing minor losses without changing velocity.

I can go to any decent exhaust shop here and they will replace the cat with a straight pipe without a second thought. In fact, some even recommend it when the cat is shot. But it's not illegal here and with our low population density and complete lack of smog the NOx and HC difference from removing my cat would not be an issue. The improvement in fuel economy and reduced cost (=energy and resources) would probably offset the bad anyway. If you're in an area where there are air quality issues, it would be disrespectful to those living near you to run without a cat, IMHO.

Do you know the condition of the cat internals? It is certainly something to check into if you're having mileage and/or power problems. I was prepared to remove the original cat on my g/f's '93 MX-6 when I did some exhaust work on it last year, but the internals still looked perfect, so I left it alone.

 

[Gary Allan]

You should look elsewhere before condemning your cat for your lousy fuel economy. ..but...to answer your original question EVERY county in PA is supposed to undergo an anti-tampering inspection as part of the safety inspection if they don't do any actual emissions testing.

Vehicles registered in the 42 counties listed on the right are NOT required to pass an emissions inspection. However, most passenger vehicles and light trucks weighing 11,000 pounds and less are required to pass a visual anti-tampering check as part of an enhanced safety inspection. Vehicles registered as classic or collectible are exempt from the anti-tampering portion of the safety inspection. The visual anti-tampering check is a visual inspection for the presence of emission control components that were installed on a vehicle by the manufacturer.


Map of Counties in the Northern Region: Blair, Cambria, Centre, Erie, Lackawanna, Luzerne, Lycoming, Mercer

Counties:
Adams, Armstrong, Bedford, Bradford, Butler, Cameron, Carbon, Clarion, Clearfield, Clinton, Columbia, Crawford, Elk, Fayette, Forest, Franklin, Fulton, Greene, Huntingdon, Indiana, Jefferson, Juniata, Lawrence, McKean, Mifflin, Monroe, Montour, Northumberland, Perry, Pike, Potter, Schuylkill, Snyder, Somerset, Sullivan, Susquehanna, Tioga, Union, Venango, Warren, Wayne, Wyoming

If you're not in one of those counties, Go here and select the region that you live in (about halfway down on the left).

So, you may not get reported ..but you may not get a badge either. YMMV.

 

[Titan]

Quote:

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ive never seen an engine minitoring device that shows the computer if there is backpressure or not. an engine cant tell the difference.

---

Right, and therein lies the problem!

rpn answered this...there is no exhaust pressure monitoring device. The concern is about the characteristics of the flow of the fuel/air charge and how this relates to exhaust gas movement as it is leaving the combustion chamber. Those flow characteristics relationships are why varible intake pathways produce more power at specific rpm ranges.

Motorcyclists have known for years that "opening up" their exhaust pathway can result in loss of torque at low rpms, and many (if not most), also lose top-end power, too. Fuel efficiency drops. Cylinder head temps rise. Pistons get holes burned into them. Many people "felt" their bike was running faster just because it was louder...until they raced their buddy's stock setup...and LOST.

The point is, again, that unless your computer can adjust sufficiently to a change in air flow patterns (intake AND/OR exhaust), then you may lose power, lose efficiency, may be operating in a potentially harmful lambda ratio, and...let's see...what else...oh yeah...you'll be polluting the air more than if you didn't have a cat.

One more thing...someone mentioned that these cars have been well known to run better when an old, plugged up cat is removed. SURE! After all, the resistance to flow has been changed from the ideal! However, it isn't logical to assume that removing resistance from the designed ideal will make it run better compared to having the correct resistance.

Look, I don't know what the effect will be as far as performance, because I've never had one of these cars on a dyno to measure the difference. Nor have I inspected the plugs to see if it is burning too lean...however, if I were to do this modification (which I wouldn't), I'd at least consider changing my spark plug heat range.

 

[onion]

It depends on the vehicle as to whether or not removing/hollowing out the cat will decrease or increase performance. On MOST vehicles, you don't really notice any performance difference between a properly functioning cat and a hollowed-out one. I HAVE seen one vehicle, though, that actually ran WORSE when the cat was removed- it was an '89 Sunbird. I imagine there are others. However, you drive a '90 Civic, which is a very popular vehicle to modify among some crowds. If removing the cat caused performance PROBLEMS, then this would be well-known. I seriously doubt that this would cause you a problem.

IF there is no emissions test in your area, then NOBODY is going to turn you in to Big Brother. Cops do not check emissions devices- most are doing well if they know how to check the oil. Nor will any shop refuse to work on your car because of it. Just don't expect any shop to do the removal/hollowing out for you. There ARE shops that will do this... but they're not in their right mind.

But, that said, how do you know that the cat. conv. is your problem? If it's NOT the problem, then you're much better off leaving it alone. In every case I've seen, a plugged converter will make the car VERY sluggish, with little throttle response... and yet they'll sometimes run OK at full-throttle. This is also often accompanied by an audible exhaust leak as the high pressure before the cat finds a way out. When this is the case, I usually unbolt the exhaust at the manifold and drive the car BRIEFLY (for obvious reasons). If performance is immediately improved, then the converter is very likely clogged.

But, then again... your OP said that you have no tools and very little DIY skills. You'll be time ahead and likely money ahead to take it to a shop.

 

[Master ACiD]

motorcyclists have known for years huh. hahaha
tell that to any harley guy. seems harley owners love running with no backpressure.

also alot of the sportbike guys install straight through mufflers, etc.

fact is that most fuel injection systems can handle + or - 16% fuel increase or decrease. they HAVE to because of hot or cold days, differing elevations, gradually plugging up air filters.
etc.

its only old fashoned carburettor engines that are effected by changes in the exhaust.

 

[Titan]

Quote:

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motorcyclists have known for years huh. hahaha
tell that to any harley guy. seems harley owners love running with no backpressure.

also alot of the sportbike guys install straight through mufflers, etc.

fact is that most fuel injection systems can handle + or - 16% fuel increase or decrease. they HAVE to because of hot or cold days, differing elevations, gradually plugging up air filters.
etc.

its only old fashoned carburettor engines that are effected by changes in the exhaust.

---

Incorrect. Apparently, you don't actually know "any Harley guy" with straight pipes. Most of these bikes' fuel systems are adjusted to the degree that there are different fuel maps designed for the particular Brand and Model of exhaust installed.

Obviously, you aren't familiar with performace work on motorcycles. The people that run straight pipes also tweak their fuel ratios, whether by changing jets on carbs, or adding fuel injector devices such as Techlusion, Cobra, which can only enrichen fuel mixtures, as well as others that can have custom maps downloaded from a Personal Computer. If they don't make these air/fuel adjustments, they end up with bikes performing worse than stock, and it also often ends up burning too lean...which is too hot...which burns holes in pistons. You can't tell by the sound what Motorcyclists are doing to their fuel mixtures when they change back-pressure in their exhausts (unless you hear the tell-tale exhaust popping on deceleration, which is from a too-lean condition, except for some of the engines that have a fresh-air induction system into the exhaust flow...such as the Reed-valve system on Kawasaki's).

Let me assure you there is more to it than just putting on straight pipes.

Yes, most ECU's can compensate a certain percentage from normal...but, when you add an additional abnormal variable to the situation as you decrease exhaust backpressure...whether the ECU can make adjustments for that PLUS the other variables that it needs to make, is unknown until you try it, and measure the results.

If you don't believe me, why don't you ask someone that works on them for a living? I've only personally tweaked about 15 myself. How many have you done, and how long did they last after your personal work on them?

 

[onion]

There are hundreds of thousands... perhaps millions of cars on the road running around with the converter removed or hollowed out. The vast, VAST majority of them run fine.

 

[Doc8404]

Quote:

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its only old fashoned carburettor engines that are effected by changes in the exhaust.

---

soooo, you are saying that a dual exhaust does nothing to a truck/car that has Fuel Injection?
Interesting......
i guess.

 

[01rangerxl]

Quote:

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There are hundreds of thousands... perhaps millions of cars on the road running around with the converter removed or hollowed out. The vast, VAST majority of them run fine.

---

Call me a tree hugger or whatever, but I just don't see the point with modern monolith cats that can be bought for relatively cheap. Many are only a little more than the cost of a muffler. Some cars, like V8 Mustangs, can see significant power gains without the cat(s), but the vast majority of cars don't.

 

[alreadygone]

Been my experience cars with single O2 sensor in fromt of converter (like a 90 Honda) can have converter safely removed. Newer vehicles with 2 sensors, one in front of converter and one behind MUST have convereter to send different signals to computer.

In reality, converters ALMOST never go bad. Your problem is likely somewhere else.

Bob

 

[onion]

There's usually some other issue with the engine to cause it (oil consumption, running rich, chronic misfire)... but converters do plug up on occasion. It's NOT a rare occurance.

And, no... I quite frankly don't give a rat's As$ if a vehicle pollutes more than it was designed to. It's none of my concern.

I'm not convinced at all that the catylitic converter is this guy's problem... but let's be clear that he can do what he ____ well pleases with his own car. Big Brother will never find out, and it will NOT hurt the car's performance. I'd simply advise against it (at this point) because it's a lot of trouble.

 

[Titan]

[quote .
I quite frankly don't give a rat's As$ if a vehicle pollutes more than it was designed to. It's none of my concern.

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Do you think it's none of your concern because it doesn't matter what one person does? Or that pollution is a non-issue? Or that ubiquitous problems are too big to correct, so...it's easier to not care? Just curious...I realize living in Kansastan can encourage isolationalism...I drive through the area more than I like to...it's desolate in many ways...not all of the desolation refers to the landscape.