wheel NISSAN 300ZX 1984 Z31 Engine Fuel And Emission Control System Workshop Manual

AIR FLOW SYSTEM DESCRIPTION
TURBOCHARGER
The turbocharger is installed on the exhaust mani-
fold This system utilizes exhaust gas energy to
spin the turbine wheel which
is directly connected
to the compressor wheel The compressor supplies
pressurized air through the throttle chamber into
the intake manifold Thus, the turbocharger in-
creases charging efficiency and thereby increases
power and torque.
To prevent an excessive rise in the supercharging
pressure, the turbine speed
is maintained within a
safe range by controlling the amount of exhaust
gas that passes through the turbine This system
consists of
a by-pass valve which allows some of
the exhaust gas to by-pass the turbine and to flow
directly into the exhaust tube
Engine speed
From b==iF exhausi man2fold 0 Superchargang pressure 41 hqh
To intake
From air flo meter
h
To intake
From air flo meter
2 Bygars valve controller
3 Compressor
4 Turbine
SEF609B
EMERGENCY RELIEF VALVE
To prevent an abnormal rise in supercharging
pressure, and possible engine damage, in case
the
by-pass valve fails to open properly, an emergency
relief valve
is provided as a safety device on the
intake manifold
When the prwre in the Intake mandold IS below 52 0 kPa 1390 mmHg. 15 35 inHgl
Upper cover
When the prerrura tn the intake mandold IS above 520 kPa 1390 mrnHg, 15 35 mHg)
Atmosphere
Charged air pressure Charged air pressure
SEF6lOB
EF & EC-12

DIAGNOSTIC PROCEDURE
Driveabil
1. Inspect engine and E C C.S. for air leaks,
proper electrical connections, etc
1) Check all hoses and ducts for air leaks
2) Check air cleaner for clogging
3) Check harness connectors for proper connec-
tions
4) Check ignition wiring
5) Check gaskets for leaks at all air intake com-
ponents
6) Check E G.R valve operation
7) Check air regulator operation
2 Perform E C C S self-diagnosis
Follow the procedure in E CCS SELF-
DIAGNOSIS (Page EF & EC-35)
3 Check idle speed and ignition timing
a. Prepare the following conditions:
Headlampswitch' OFF
Heater blower: OFF
Air conditioner switch: OFF
Front wheel (Power steering model):
KEEP STRAIGHT AHEAD
b. Warm engine to operating temperature.
Check
and adjust as follows
[VG30E engine (Without turbocharger)]
1) Stop engine and disconnect idle-up solenoid
valve harness connector
Idle-up solenoid
2) Start engine and race engine two or three times
under no-load, then run engine
at idle speed
(Cont'd)
3) Check idle speed
M/T & A/T (in "D" position)
700250 rpm at sea level
650250 rpm at high altitude condition
If necessary, adjust to the specified
speed by
turning idle speed adjusting screw
I, SEF6456
4) Stop engine and connect idle-up solenoid valve
harness connector
5) Start engine and check ignition timing with
a
timing light
20ai2" B.T.D.C.
If necessary, adjust ignition
timing by turning
distributor
[VG30ET engine (With turbocharger)]
1) Race engine two or three times under no-load,
then run engine at idle speed
2) Check idle speed.
M/T: 70W50rpm
A/T: 650k50 rpm (in "D" position)
EF & EC-30

TURBOCHARGER
Disconnected or cracked rubber hose
I ~~ ~
~ Condition 1 Low engine power
Probable cause Corrective action I
Correct or replace rubber hose
Air leak at the connection of compressor housing and
suction hoselinlet tube, or inlet tube and intake manifold Correct the connection
Correct the connection or replace gasket Exhaust gas leak at the connection of turbine housing
and exhaust manifold. connectina tube or exhaust outlet
I - I I I
Stuck or worn journal or bearing
Replace turbocharger assembly
Broken turbine wheel I--+
I Condition 2 Excessively high engine power 1
EF & EC-66

TURBOCHARGER
Worn journal or bearing
Inspection (Cont’d)
Replace turbocharger assembly
I Condition 3 Excessively high oil consumption or exhaust shows pale blue smoke I
Probable cause Corrective action
Oil leak at the connection of lubricating oil passage Correct the connection
1. Inspect turbine and compressor wheel as
follows
Visually check for cracks, clogging, deformity
or other damage
Revolve wheels to make sure that they turn
freely without any abnormal noise or friction
Measure play in axial direction
Play (axial direction):
0.013.0.091 mm (0.0005 - 0.0036 in)
SEF726B
2 Check operation of by-pass valve controller
Move by-pass valve to make sure that
it is not
sticking or scratched.
Measure rod end play of the bypass valve con-
troller
Do not apply more than 66.7 kPa (500 mmHg,
19.69 mHg) pressure to controller diaphragm
0.38 mm (0.0150 in)/51.3 - 56.7 kPa
(385 - 425 mmHg, 15.16 - 16.73 inHg)
By-pass valve controller strokelpressure.
,vMercury manometer
,-By-parr valve controller
SEC7278
Always replace the turbocharger as an assembly if
faultv
EF & EC-67