What is the effect of a blocked idle jet on engine performance?

A blocked idle jet has a profound impact on engine performance, particularly at idle. The idle jet is responsible for supplying fuel when the engine operates at low RPMs, such as during idling or in the initial phase of acceleration. When the idle jet is blocked, the engine may not receive the necessary fuel, leading to insufficient combustion. This deficiency can manifest as rough idling, where the engine runs erratically instead of smoothly. In more severe cases, the engine may stall entirely when trying to maintain a low-speed operation because it lacks the proper fuel-air mixture required for continued running at idle. Thus, the primary consequence of a blocked idle jet is indeed rough idling and potential stalling, highlighting its critical role in maintaining optimal engine performance during low-speed conditions.