What are the symptoms of an intake manifold leak?

[DelEzra]

The symptoms of an intake manifold leak are as follows: 1. When the intake manifold leaks, the pressure inside the intake manifold changes because it does not match the normal intake channel, causing abnormal pressure detection; 2. A common symptom is an overly lean air-fuel mixture, where the intake air volume increases significantly. Since the fuel injection amount is primarily determined by the intake air volume, more air leads to increased fuel injection, resulting in higher idle speed or irregular intake due to the leak, which may cause fluctuating idle speeds; 3. Another symptom occurs when the ECU detects an idle state through the throttle position sensor, but the idle speed is not within the specified range. The ECU then automatically adjusts the idle air control valve, leading to fluctuating idle speeds. If the leak is minor, it may only cause a slightly higher idle speed without erratic fluctuations.