What will a clogged nozzle orifice indicate when testing a 'closed' type fuel injection nozzle?

A clogged nozzle orifice in a 'closed' type fuel injection nozzle will primarily disrupt the spray pattern, leading to a distorted or uneven fuel delivery. This is due to the fact that a properly functioning nozzle is designed to atomize fuel into a fine mist to ensure complete combustion within the engine's combustion chamber. When the orifice is clogged, the fuel cannot flow as intended, resulting in a spray that may be erratic or poorly shaped. This distorted spray pattern can compromise engine performance, increase emissions, and lead to incomplete combustion, which further exacerbates engine issues.

In contrast, while other sounds associated with the operation of the injection nozzle may occur for various reasons, they are secondary to the fundamental issue of how fuel is delivered. A distorted spray pattern is the most direct indicator of a clog, hence making it the correct answer.