1986 TOYOTA SUPRA Service Repair Manual

THROTTLE BODY
ON±VEHICLE INSPECTION
Throttle Body
INSPECT THROTTLE BODY
(a) Check that the throttle linkage moves smoothly.
(b) Check the vacuum at each port.
wStart the engine.
wCheck the vacuum with your finger.
 Port name At idle At 3,000 rpm
 P No vacuum Vacuum 
 E
 
 No vacuum
 
 Vacuum
 R No vacuum Vacuum
Throttle Position Sensor
INSPECT THROTTLE POSITION SENSOR
(a) Disconnect the throttle position sensor connector.
(b) Disconnect the throttle opener vacuum hose from the throttle
body.
(c) Apply vacuum to the throttle opener.
(d) Insert a feeler gauge between the throttle stop screw and
stop lever.
(e) Using an ohmmeter, measure the resistance between each
terminal.
 
 
Clearance between
Lever and stop screw 
 Between terminals 
 Resistance
 0 mm (0 in.) VTA±E2 0.34±6.3 k

 0.40 mm (0.016 in.) IDL±E2 0.5 k
or less
 0.60 mm (0.024 in.) IDL±E2 Infinity 
 
 
Throttle valve fully
Open
 
 
 
VTA±E2
 
 
 
2.4±11.2 k

 ± VC±E2 3.1±7.2 k

(f) Reconnect the throttle position sensor connector.
(g) Reconnect the throttle opener vacuum hose to the throttle
body.
± ENGINESFI SYSTEM (2JZ±GE)EG±219

Dashpot
1. WARM UP ENGINE
Allow the engine to warm up to normal operating tempera-
ture.
2. CHECK IDLE SPEED
Idle speed (Transmission in neutral position):
700 + 50 rpm
3. CHECK AND ADJUST DASHPOT SETTING SPEED
(a) Disconnect the control cables from the throttle body.
(b) Push the dashpot push rod all the way with a screwdriver.
(c) Check that the dashpot is set.
Dashpot setting speed:
M/T
2,600 + 400
A/T
1,800 + 400 rpm
(d) Adjust the dashpot setting speed by turning the dashpot
adjusting screw.
(e) Reconnect the control cables to the throttle body.
4. CHECK VTV OPERATION
(a) Maintain the engine speed at 3,500 rpm.
(b) Release the throttle valve, and check that the engine returns
to idle in a few seconds.
Throttle Opener
1. WARM UP ENGINE
Allow the engine to warm up to normal operating tempera-
ture.
2. CHECK IDLE SPEED
Idle speed (Transmission in neutral position):
700 + 50 rpm
3. CHECK THROTTLE OPENER SETTING SPEED
(a) Disconnect the throttle opener vacuum hose from the throttle
body, and plug the throttle body port.
(b) Maintain the engine speed at 2,500 rpm.
(c) Release the throttle valve.
(d) Check that the throttle opener is set.
Throttle opener setting speed:
1,500 + 400 rpm
If the throttle opener setting speed is not as specified, replace
the throttle body.
(e) Reconnect the throttle opener vacuum hose to the throttle
body. EG±220
± ENGINESFI SYSTEM (2JZ±GE)

COMPONENTS FOR REMOVAL AND
INSTALLATION
± ENGINESFI SYSTEM (2JZ±GE)EG±221

THROTTLE BODY REMOVAL
Installation is in the reverse order of removal.
1. DRAIN ENGINE COOLANT
2. DISCONNECT CONTROL CABLES FROM THROTTLE
BODY
3. REMOVE INTAKE AIR CONNECTOR PIPE
(a) Disconnect these hoses:
(1) PS air hose from air connector pipe
(2) PCV hose from No.2 cylinder head cover
(b) Loosen the 2 hose clamps, and remove the air connector
pipe together with the hoses.
4. DISCONNECT THROTTLE BODY BRACKET FROM
THROTTLE BODY AND CYLINDER HEAD
Remove the 4 nuts, and disconnect the throttle body bracket
from the throttle body and cylinder head.
Torque: 21 NVm (210 kgfVcm, 15 ftVlbf)
5. REMOVE THROTTLE BODY
(a) Disconnect these connectors and hoses from the throttle
body:
(1) Throttle position sensor connector
(2) IAC valve connector
(3) 4 vacuum hoses
(4) California only:
Air hose (from intake manifold)
(5) Water bypass hose (from No.2 water bypass pipe)
(b) Remove the 2 bolts and 2 nuts.
Torque: 21 NVm (210 kgfVcm, 15 ftVlbf)
(c) Slightly slide the throttle body away from the intake air
connector. EG±222
± ENGINESFI SYSTEM (2JZ±GE)

(d) Disconnect the water bypass hose (from the water outlet)
from the throttle body.
(e) Remove the throttle body and gasket.
INSTALLATION HINT: Use a new gasket.
INSPECTION OF THROTTLE BODY
Throttle Body
1. CLEAN THROTTLE BODY
(a) Using a soft brush and carburetor cleaner, clean the cast
parts.
(b) Using compressed air, clean all the passages and apertures.
NOTICE: To prevent deterioration, do not clean the throttle
position sensor, dashpot and throttle opener.
2. INSPECT THROTTLE VALVE
(a) Disconnect the throttle opener vacuum hose from the throttle
body.
(b) Apply vacuum to the throttle opener.
(c) Check that there is no clearance between the throttle stop
screw and throttle lever when the throttle valve is fully closed.
(d) Reconnect the throttle opener vacuum hose to the throttle
body.
Throttle Position Sensor
1. INSPECT THROTTLE POSITION SENSOR
(See on±vehicle inspection)
2. IF NECESSARY, ADJUST THROTTLE POSITION
SENSOR
(a) Loosen the 2 set screws of the sensor.
± ENGINESFI SYSTEM (2JZ±GE)EG±223

(b) Insert a 0.50 mm (0.020 in.) feeler gauge between the throttle
stop screw and stop lever.
(c) Connect the tester probe of an ohmmeter to the terminals IDL
and E2 of the sensor.
(d) Gradually turn the sensor clockwise until the ohmmeter
deflects, and secure it with the 2 set screws.
(e) Recheck the continuity between terminals IDL and E2.
 
 
 
Clearance between
lever and stop screw
 
 
 
Continuity (IDL±E2)
 0.40 mm (0.016 in.) Continuity
 0.60 mm (0.024 in.) No continuity
EG±224± ENGINESFI SYSTEM (2JZ±GE)

IDLE AIR CONTROL (IAC) VALVE
ON±VEHICLE INSPECTION
1. INSPECT IAC VALVE FOR OPERATING SOUND
Check that there is a clicking sound immediately after stop-
ping the engine.
If operation is not as specified, check the IAC valve, wiring
and ECM.
2. California only:
INSPECT AIR ASSIST SYSTEM
A. Warm up engine
Allow the engine to warm up to normal operating tempera-
ture.
B. Check idle speed
Idle speed (Transmission in neutral position):
700 + 50 rpm
C. Check IAC valve operation
With engine idling, pinch the air hose and check that engine
speed drops, and then returns back up to idle speed.
If operation is not as specified, check the IAC valve, wiring
and ECM.
3. INSPECT IAC VALVE RESISTANCE
Using an ohmmeter, measure the resistance between the ter-
minals (B1 (or B2) to others).
Resistance:
At 20°C (68°F) 18±22

If the resistance is not as specified, replace the IAC valve.
± ENGINESFI SYSTEM (2JZ±GE)EG±225

COMPONENTS FOR REMOVAL AND
INSTALLATION
EG±226± ENGINESFI SYSTEM (2JZ±GE)