When the engine is running, the air intake valve is lifting up.
If the valve does not operate properly, check the air intake solenoid valve hoses for leak.
If there are no leaks, check the air intake solenoid valve.

Air Intake Solenoid Valve Unit TestBrake Line Bleeding
The brake fluid has a very low compression coefficient so
that almost all the movement of the brake lever or pedal
is transmitted directly to the caliper for braking action. Air,
however, is easily compressed. When air enters the brake
lines, brake lever or pedal movement will be partially used
...
DFI System
1. ECU
2. Battery
3. Vehicle-down Sensor
4. Exhaust Butterfly Valve Actuator
5. Vacuum Chamber (Other than US, CA and CAL Models)
6. Air Intake Valve Actuator (Other than US, CA and CAL Models)
7. Air Intake Valve (Other than US, CA and CAL Models)
8. Air Flow
9. Air Intake Solenoid Valve ...
Wheel Rotation Sensor Air Gap Inspection
Raise the front/rear wheel off the ground (see Front/Rear
Wheel Removal in the Wheels/Tires chapter).
Measure the air gap between the sensor and sensor rotor
at several points by turning the wheel slowly.
Thickness Gauge [A]
Wheel Rotation Sensor Air Gap
Standard:
Front 0.4 1.6 mm ...