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 TestTachometer
The tachometer shows the engine
speed in revolutions per minute (r/min,
rpm).
On the right side of the tachometer
face is a portion called the “red zone”.
Engine r/min (rpm) in the red zone is
above maximum recommended engine
speed and is also above the range for
good performance.
...
Camshaft Chain Tensioner Installation
Replace the O-ring [A] with a new one.
Apply grease to the new O-ring.
Release the stopper [B] and push the push rod [C] into the
interior of the tensioner body [D] so that the position of the
push rod is 3 or 4 notches [E] as shown in the figure.
Install the tensioner body so that the ...
Camshaft Installation
NOTE
The exhaust camshaft has a 1001 EX mark [A] and the
intake camshaft has a 3154 IN mark [B]. Be careful not
to mix up these shafts.
Install the camshaft sprockets as shown in the figure.
#4 Cam Positions [A]
Intake Camshaft Sprocket [B]
Exhaust Camshaft Sprocket [C]
The int ...