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Catalytic converter

A friend says that removing the catalytic converter will do no harm and might improve gas mileage. I claim that the computer chip will be confused and cause all kind of problems. Have a dinner riding on this. Thank you

Early cars, '75 to about '89 had fairly restricted convertors and would run better without them. If the car is about '90 or newer, the convertor is very free flowing and won’t cause much HP loss. Any car built after 1996 will have an oxygen sensor in front of and behind the catalytic convertor. If you remove the convertor, the engine computer will flag an error and light the “check engine” light on your dash. I can’t say for sure, depending on the type of car and its condition, it could run the same, better or worse. There’s no sure-fire way to know without testing. Either way, removing the convertor is a violation of federal and most state laws and “cause all kinds of problems” that maybe you hadn’t anticipated (like eating prison food for that dinner).

I wouldn’t do this on fuel-injected a car post 1990. It’s unlikely to improve anything, and may cause unexpected problems. Carburated cars earlier than 1990 it might make some sense, provided removing the cat is legal where you live.

Yeah I agree. Notwithstanding it being quite illegal now, there’s no reason to unless it is plugged. In the old days they used to sell “test pipes” that were sections of exhaust to replace the cat to test (wink wink) if the cat was a problem. That all changed with the computer systems and O2 sensors. So in the old day yeah but now no.

+1 for Bing. There is a fine for removing the cat but the numbers keep changing. It’s $2500, $2750 or $10,000 depending on the website that you go to for the information.

I think your friend owes you a dinner.

I worked one of my X’s '00 Monte Carlo that had a plugged Cat. Upon doing some research, I found a place that sold “test pipes” for the exhaust system. They also sold an “adapter chip” that plugged into the harness in place of the rear O2 sensor. This chip would let the ECU know that all is good with the reading it was getting and not turn on the SEL.

I begged her to get the vehicle repaired properly as soon as possible but as usual, she did not listen and as far as I know, it is still on there. Haven’t seen her in a couple years.

Definitely not recommended to remove the cat on a late model car.

I had a 1976 Ford Granada with a 351 Windsor V8. This was the first model with a cat and it was really slugggish. Removing it made the car run better.