Final answer:
Yes, the compression ratio is decreased when combustion chamber deposits accumulate in the engine, which can affect engine efficiency and performance.
Step-by-step explanation:
Yes, the compression ratio is decreased when a large volume of combustion chamber deposits accumulate in the engine. The compression ratio refers to the ratio of the volume of the combustion chamber at the start of the compression stroke to the volume at the end of the compression stroke. Accumulation of deposits in the combustion chamber increases the volume, thereby reducing the compression ratio. This can negatively impact the efficiency and performance of the engine.