What are the symptoms of abnormal intake manifold vacuum?
1 Answers
Symptoms of abnormal intake manifold vacuum are as follows: 1. It can cause weak engine operation. 2. It may lead to difficulty in engine starting. 3. It can affect emissions. 4. It may result in unstable idle. The effects of intake manifold air leakage on the engine mainly include the following aspects: 1. Abnormal intake manifold vacuum can cause weak engine operation: If the intake manifold vacuum is too low at idle, it indicates that air is entering the intake manifold through bypass routes. Since this air is not measured by the mass air flow sensor or controlled by the throttle, the sensor's reading will be lower than the actual intake air volume. The ECU determines the basic fuel injection quantity based on signals from the mass air flow sensor, leading to insufficient fuel injection and an overly lean air-fuel mixture, resulting in weak engine operation. 2. Abnormal intake manifold vacuum can cause difficulty in engine starting: If the circular cover at the end of the intake manifold's upper stabilizer chamber falls off, excessive air intake will make the air-fuel mixture too lean, causing difficulty in engine starting. 3. Abnormal intake manifold vacuum can affect emissions: Reduced intake manifold vacuum increases engine load and combustion chamber temperature, raising the peak temperature of exhaust gases per cycle, which leads to higher NOx emissions. 4. Abnormal intake manifold vacuum can cause unstable idle: If there is an intake manifold air leak, the mass air flow sensor cannot accurately measure the real intake air volume, causing the ECU to inaccurately control the air intake, resulting in unstable engine idle.
