What are the draw backs of removing my converter
Violating federal law and possibly getting a very large fine. Any independent shop can replace it if it is bad . And if it is check with the dealer because it should be under the emissions warranty.
2 Likes
What are the advantages of removing your converter? None
2 Likes
Count me wrong if so, but my old fart brain tells me it produce back pressure that the engine is designed for to run properly.
1 Like
A $20,000 fine. For starters.
Tester
2 Likes
Lots of people do this, but it is not without drawbacks.
The first thing that you will notice is the check engine light that results from the computer not getting the reading it expects from the post-catalyst oxygen sensor. Hot rodder forums will tell you how to fool the computer by sending it a constant (~4.5V) signal on the rear oxygen sensor wire. That is the easy problem.
The next problem will be when the computer does an EGR system check. With too little back pressure in the exhaust, the EGR flow will be low, and it will probably fail the system check. Another check engine light. That also can be tricked, but not so easily.
I think there will be a couple more system checks that you have to get around as well, but they don’t come to mind at the moment.
Then there is the fact that most folks object to breathing excess NOx, CO, and ozone that result from your modification… Anyone who works on the car may turn you in to the authorities.
Then if you ever try to sell the car, your legal problems could really get dicey.
2 Likes
Don’t you mean morons?
Tester
4 Likes
People do remove cats and replace them with test pipes.
As noted, it is against the law and you will need to trick out the rear O2 sensor. I hadn’t heard about the EGR back-pressure concern, but it sounds reasonable.
If your state does emission inspections, you may be risking trouble (getting turned in) if they spot a test pipe. Or even getting pulled over and the officer spotting a test pipe could mean trouble, which is why some opt to hollow out (or gut) their cat.
Can you help us understand what benefit you’re looking for by removing the cat?
There’s a lot of upside to leaving it in.
1 Like
+1
Back in the very early days of catalytic converters, there was some popular “wisdom” that one’s car would perform “better” if the catalytic converter was disabled by using leaded gas. A number of old coots in my town who believed that nonsense purposely filled their tanks with leaded gas until their cats ceased to function. Not only did their cars not perform better, but when the state introduced emissions testing a couple of years later, they had to spend a lot of money to replace those cats.
I thought the EPA had banned test pipes, I have not seen one for sale in a long time in reputable parts stores.
I then googled them and saw dozens of different ones for sale, some even looking like real converters with oxygen sensor bungs.
Back in the very early days of catalytic converters, there was some popular “wisdom” that one’s car would perform “better” if the catalytic converter was disabled by using leaded gas. A number of old coots in my town who believed that nonsense purposely filled their tanks with leaded gas until their cats ceased to function. Not only did their cars not perform better,
I need to respectfully disagree.
I gutted out many cats years ago. When the cats arrived around 1975, so did carburetor jets with narrower openings, and timing curves with retarded timing.
Removing or gutting the cat was not sufficient. You also had to drill out the carburetor main jets, and advance the base timing till it pinged, and then back off a hair.
If I had old distributor advance springs, I’d use those where applicable.
The carb jets only needed to be opened a couple of thousands of an inch, back to the diameter they were prior to the cat arriving.
In every car I did, both power and mpg noticeably improved. Many I did it for were amazed at the difference.
The old pellet style cats were pretty awful and I admit to hollowing one out myself… in 1981 in a state with no inspections.
That said, a modern 3 way honeycomb cat will not restrict flow hardly at all. A quiet muffler has similar back pressure. If your area has emissions inspections you WILL fail a visual inspection, no question.
And we all breathe the same air.
What are you trying to achieve?
With so little to gain and so much to lose it’s hard to understand why anyone would want to remove their catalytic converter. Maybe if driving on dry pasture regularly it could be worthwhile.
Doing that would make you a moron.
Tester
The check engine light turning on is the main practical drawback for the emissions-uninterested owner. That’s more of a problem than it might seem, b/c since it remains on all the time, you lose the ability to tell if a new problem has occurred. As for the upside, unless the cat is badly clogged, unlikely to see much in the way of performance gains.
It’s more than the light. The computer can’t get the fuel mixture correct without the cat. So one more time, why do this?
Is it that?
Or is it the computer uses the upstream O2 sensor for the mixture, and uses the downstream (rear) O2 sensor to verify the cat is working correctly? I understood it being the latter.
The rear O2 sensor can easily be tricked into thinking everything is fine.
Yes, but I wonder if the OP would know how to do it.
Bigger point - it’s a bad idea, for all the reasons above.
Why would you remove it on a 2 year old car ?