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 TestStarter Motor Assembly
Install the positive brush assy [A] and the starter motor
terminal [B] as shown in the figure.
Replace the O-ring [C] with a new one, and install it.
Install:
Brush Springs [A]
Negative Brush Assy [B]
Turn the stopper side [C] to inside.
Tighten:
Torque - Brush Holder S ...
Stick Coil Inspection
Remove the stick coils (see Stick Coil Removal).
Measure the primary winding resistance [A] as follows.
Connect the hand tester between the coil terminals.
Set the tester to the × 1 Ω range, and read the tester.
Measure the secondary winding resistance [B] as follows.
Conn ...
Alternator Rotor Removal
Remove the alternator cover (see Alternator Cover Removal).
Clean off the oil from the outer circumference of the rotor.
Hold the alternator rotor steady with the rotor holder [A]
and suitable washer or plate [B].
Special Tools - Grip [C]: 57001-1591
Rotor Holder: 57001-1666
Flywheel P ...