Remove catalytic converters?

Feb 2, 2004
There should be no change to the fuel mixture with the cats removed. The upstream O2 sensor controls closed loop fueling the downstream O2 only reports cat function. It might smell rich because it is releasing more pollutant but the actual engine fueling will not change. I don't recommend doing it on a stock engine with working cats but just putting the correct into out there.

If the CEL is always on and the exhaust smells bad, you're overfueling all the time.

This is why they install the diode or whatever in the O2 sensor harness to fool the ECU into thinking everything is normal. This will improve the gas mileage a bit and should help some with the fuel smell exhaust.

If you like throwing codes, running rich and smelling like a janky old lawnmower, that's your prerogative.

I personally wouldn't do anything to deliberately worsen the air quality where I live, and I hope most of my neighbors feel the same way.

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