INTAKE AND EXHAUST – On-vehicle Service
15-3
(3) If the boost pressure is lower than the standard value,
check for following which are probably the cause:
D Wastegate actuator inoperative
D Boost pressure leak
D Turbocharger defective
(4) If the boost pressure is higher than the standard value,
boost pressure control is probably faulty. Make the
following checks:
D Wastegate actuator inoperative
D Wastegate valve inoperative
D Wastegate actuator rubber hose disconnected or
cracked
2. BOOST PRESSURE CONTROL SYSTEM
CHECK
(1) Disconnect the hose (black) from the wastegate solenoid
valve and connect a three-way joint between the hose
and solenoid valve.
(2) Connect a hand vacuum pump to the three-way joint.
(3) Disconnect the hose (black) from the intake pipe nipple
connected to the turbocharger compressor housing and
fit a blank plug to this nipple.
(4) Disconnect the negative cable from the battery, keep it
disconnected for 10 sec. or more, and then reconnect
it back again.
(5) Block and unblock the end of the vacuum hose (black)
with a finger to apply vacuum and check for the vacuum
condition.
Engine condition Hose (black) end Normally
Stationary
Unblocked Vacuum leaks.
gn
on sw
c
:
Blocked Vacuum retained.
Idling after warmup Vacuum leaks.
NOTE
If the vacuum condition is faulty, the wastegate actuator,
wastegate solenoid valve, or hose is probably defective.
Wastegate
solenoid valve