The intake manifold pressure of Fox 1.8 idle engine is too high.

Solution to excessive intake manifold pressure of Fox 1.8 idle engine:

1. Throttle opening: The smaller the throttle opening, the greater the suction effect formed by the piston during air intake, the greater the suction of the intake manifold and the greater the vacuum degree, that is, the smaller the intake pipe pressure (at this time, the suction of the intake manifold is opposite to its suction).

2. Engine speed: The higher the engine speed, the greater the suction effect formed by the piston during intake, the greater the suction force of the intake manifold and the greater the vacuum degree, that is, the smaller the intake manifold pressure.

Three: sealing performance: including the sealing performance of intake manifold and cylinder. The better the sealing performance, the greater the intake manifold suction and the greater the vacuum, that is, the smaller the intake manifold pressure.