We dive into the Toyota Prius that came in originally with a lack of power when accelerating. After discussions with the owner of the vehicle and recent repair history, we discovered an interesting situation.
After elsewhere repaired an exhaust leak at the exhaust donut, the vehicle started to exhibit a serious symptom of no power when accelerating. We determined that the original leak was caused by excessive back pressure from a clogged/restricted catalytic converter.
The converter substrate is a honeycomb style filter that is compromised of rhodium, platinum, and palladium. These precious metals that coat the converter allow for the catalyst (a speeding up of a gas change); converting the spent noxious gas fumes of carbon monoxide to spew through the substrate and ultimately out of the tailpipe as carbon dioxide. When this substrate starts to come apart, it can lodge in the exhaust piping, causing restriction and a lack of flow—in turn, a serious lack of power when accelerating.
It is important to understand that excessive, or partially-burnt fuel remnants that are deposited into the bed of this substrate can cause damage. If your upstream air-fuel management is not operating efficiently this eventually can be a problem for the catalytic converter.
Always ensure that the spark plugs, along with remaining secondary ignition components are working as designed with no faults or wear. They just will not be able to properly burn the fuel in the combustion chamber. Additionally, it is imperative to ensure then fuel injectors are atomizing the fuel and not misting droplets of fuel. This raw unburnt fuel can cause serious damage to the Catalytic Converter.
Remember that these converters usually do not go bad on their own, and more than likely there are other causes to failure.