Removing removal catalytic converter EX343

[abenji69]

I am looking to removing either the Catalyst or the entire catalytic converter from my ex343. Has anyone done that?? Removing just the material may be the easiest. I can put a o2 sensor bypass for the codes if needed. Just looking for anyones input. Thanks in advance

[Peter6000]

I would assume these have a closed loop fueling system, you would have to reprogram the ecu. Where are the o2 sensors pre or post cat.? Or both?

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[abenji69]

I assume you mean closed loop cooling? Not it is conventional fresh water, It does appear there are 2 sets of sensors one right at the manifold and the other a bit further down the line,

[core-rider]

I’m your last pic… the sensor on the top left is the O2 sensor. The sensor on the bottom right looks like a temp sensor. Are there similar sensors on the other side of the engine?

Why do you want to remove the CATs?


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[abenji69]

Yes you are correct.. There are 2 sets O2 sensors on each side in the back plus 2 that are hidden on the bottom side of the post Cat.. Not really sure why I want to delete it.. I just feel without it there I will get a little more power form what I know.. pics here.. 24

[core-rider]

Not sure the juice is worth the squeeze… the minor amount of power you might get won’t be worth all the headaches with the computer I believe.

Modern CATs aren’t the air choke they were back in the day. Look at these modern cars making unreal HP numbers from the factory with them. I think you’re best to leave it be if there’s not a mechanical reason for removal/testing.


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[abenji69]

You are probably on to something.. Who needs a headache when all you want to do is ski! Thanks

[Peter6000]

I assume you mean closed loop cooling? Not it is conventional fresh water, It does appear there are 2 sets of sensors one right at the manifold and the other a bit further down the line,

I did mean closed loop fuel control, the O2 sensor measures the air fuel ratio and compares to a fuel table stored in the ecu and adjust fuel injection if needed.
This is done by the pre cat sensor.
Removing this would lower engine performance.
The post cat sensor is only there to make sure the cat is functioning.
You can replace the past cat sensor with a simulator and may get rid of the check engine warning.
I would not touch the pre cat sensor.
It would be better to reprogram the ecu search in automotive forums in cars that use the same engine there usually more information.
Why do you want to remove the cat?

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[Peter6000]

Yes you are correct.. There are 2 sets O2 sensors on each side in the back plus 2 that are hidden on the bottom side of the post Cat.. Not really sure why I want to delete it.. I just feel without it there I will get a little more power form what I know.. pics here.. 24

I strongly doubt that you would gain any power by removing them.


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[scottb7]

The question I would be wondering is will you gain enough power to help do anything? What problem are you trying to solve? What experience are you trying to improve? And would you know it if you achieved it? How would the gain be measured?

But I also understand just wanting to tinker with stuff and see what happens. So yeah, go for it and tell us what happened.

I think at age 54, my lifetime ratio is about 50/50 for broke it vs. fixed it....

[SilentSeven]

Back in the old days - when cats were a slap on for quick emissions control - pulling your cat was a quick hack to uncork the engine breathing. But today's engine systems are factory designed to work with the cat for maximum output. So...fun hypotheticals here but I wouldn't do it for the following reasons.

1) As others have noted, the ECU expects to see pre and post cat readings as part of the emissions control loop which ties to the fueling and advance algorithms. Removing the cats will eff up the ECU inputs and trigger check engine conditions. So unless you have a proven ECU reprogramming plan all you will do is mess up 1000's of hours of engineering work,

2) I personally wouldn't purchase a boat with the systems removed or modified. Too much $ at stake to put back into factory condition and it would make me question what else on the boat would have similar oddities.