ect LEXUS SC300 1991 Service Repair Manual

Idle Speed Control (ISC) Valve
ON±VEHICLE INSPECTION
INSPECT ISC VALVE FOR OPERATING SOUNDCheck that there is a clicking sound immediately after stop-
ping the engine.
If the rpm operation is not as specified, check the ISC valve,
wiring and ECU.
±
EFI SYSTEM Air Induction System (Idle Speed Control (ISC) Valve)FI±53
WhereEverybodyKnowsYourName

COMPONENTS
REMOVAL OF ISC VALVE
1. REMOVE THROTTLE BODY (See page FI±45)
2. REMOVE ISC VALVE Remove the two screws, ISC valve and O±ring.
INSPECTION OF ISC VALVE
1. INSPECT ISC VALVE RESISTANCEUsing an ohmmeter, measure the resistance between the ter-
minals (B1±S1 and S3, B2±S2 and S4).
Resistance: 10±30

If resistance is not as specified, replace the ISC valve.
FI±54
±
EFI SYSTEM Air Induction System (Idle Speed Control (ISC) Valve)
WhereEverybodyKnowsYourName

2. INSPECT ISC VALVE OPERATION(a) Apply battery voltage to terminals B1 and B2, and whilerepeatedly grounding S1±S2±S3±S4±S1 in sequence,
and check that the valve moves toward the closed
position.
(b) Aplly battery voltage to terminals B1 and B2, and while repeatedly grounding S4±S3±S2±S1±S4 in sequence,
and check that the valve moves toward the open
position.
If operation is not as specified, replace the ISC valve.
INSTALLATION OF ISC VALVE
(See Components on page FI±54)
1. INSTALL ISC VALVE
(a) Install a new O±ring on the throttle body.
(b) Install the ISC valve with the two screws.
2. INSTALL THROTTLE BODY (See page FI±45)
±
EFI SYSTEM Air Induction System (Idle Speed Control (ISC) Valve)FI±55
WhereEverybodyKnowsYourName

Acoustic Control Induction System (ACIS)
ON±VEHICLE INSPECTION
INSPECT IACV(a) Using a 3±way connector, connect vacuum gauge to the
actuator hose.
(b) Start the engine.
(c) While the engine is idling, check that the vacuum gauge needle does not move.
(d) Repidly depress the accelerator pedal to fully open position and check that the vacuum gauge needle
momentarily fluctuates approx. 53.3 kPa (400 mmHg,
15.75 in.Hg). (The actuator rod is pulled out.)
FI±56
±
EFI SYSTEM Air Induction System (Acoustic Control Induction System (ACIS)
WhereEverybodyKnowsYourName

COMPONENTS
REMOVAL OF ACOUSTIC CONTROL
INDUCTION SYSTEM (ACIS)
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Turn the ignition switch to ºLOCKº. Discon-
nect the cable from the negative (±) terminal of the bat-
tery. Wait at least 20 seconds before proceeding with
work.
2. (A/T) REMOVE DIPSTICK GUIDE FOR TRANSMISSION
(a) Remove the mounting bolt.
(b) P u ll ou t th e dip stick gu id e an d dip stick fro m th etransmission.
(c) Remove the O±ring from the dipstic guide.
±
EFI SYSTEMFI±57
Air Induction System (Acoustic Control Induction System (ACIS)
WhereEverybodyKnowsYourName

3. REMOVE VACUUM CONTROL VALVE SET(a) Disconnect the connector from the VSV.
(b) Disconnect the following hoses:(1) Vacuum hose from VSV
(2) Vacuum hose from vacuum pipe
(c) Remove the two nuts and vacuum control valve set.
4. REMOVE VACUUM TANK AND VSV Remove the screw, vacuum hose and VSV from the vacuum
tank.
5. REMOVE OIL DIPSTICK FOR ENGINE
6. DISCONNECT NO. 2 VACUUM PIPE Remove the two nuts and disconnect the vacuum pipe.
7. REMOVE EGR PIPE (a) Loosen the union nut.
(b) Remove the two bolts, EGR pipe and gasket.
8. REMOVE AIR INTAKE CHAMBER (a) Disconnect the following hoses:(1) Vacuum hose from brake booster union
(2) Air hose (from charcoal canister)
(3) Vacuum hose from vacuum pipe
(4) Vacuum sensing hose
(5) Air hose (from PS air control valve)
FI±58
±
EFI SYSTEM
Air Induction System (Acoustic Control Induction System (ACIS)
WhereEverybodyKnowsYourName

(b) Remove the six nuts and five bolts holding the intake airconnector to the air intake chamber.
(c) Disconnect the check connector and harness protector from the air intake chamber.
(d) Remove the five bolts, two nuts, intake air chamber and two gaskets.
INSPECTION OF ACOUSTIC CONTROL
INDUCTION SYSTEM (ACIS)
1. INSPECT IACV (a) With 53.3 kPa (400 mmHg, 15.75 in.Hg) of vacuumapplied to the actuator, check that the actuator rod
moves.
(b) One minute after applying the vacuum in (a), check that the actuator rod does not return.
If the operation is not as specified, turn the adjusting screw.
2. INSPECT VACUUM TANK (a) Check that air flows from port A to port B.
(b) Check that air does not flow port B to port A.
(c) Plug port B with your finger, and apply 53.3 kPa (400
mmHg, 15.75 in.Hg) of vacuum to port A, and check that
there is no changer in vacuum after one minute.
If the operation is not as specified, replace the vacuum tank.
±
EFI SYSTEMFI±59Air Induction System (Acoustic Control Induction System (ACIS)
WhereEverybodyKnowsYourName

3. INSPECT VSV
A. Inspect VSV for open circuitUsing an ohmmeter, check that there is continuity, between
the terminals.
Resistance (Cold): 38.5±44.5
at 20 5C (68 5F)
If there is no continuity, replace the VSV.
B. Inspect VSV for ground Using an ohmmeter, check that there is no continuity be-
tween each terminal and the body.
If there is continuity, replace the VSV.
C. Inspect VSV operation (a) Check that air flows from port E to the filter.
(b) Apply battery voltage across the terminals.
(c) Check that air flows from port E to port F.
If operation is not as specified, replace the VSV.
FI±60
±
EFI SYSTEM
Air Induction System (Acoustic Control Induction System (ACIS)
WhereEverybodyKnowsYourName

INSTALLATION OF ACOUSTIC CONTROL
INDUCTION SYSTEM
(See Components on page FI±57)
1. INSTALL AIR INTAKE CHAMBER (a) Place a new gasket so the protrusion faces the intake
chamber.
(b) Install a new gasket to the intake manifold, and the intake chamber with the five bolts and two nuts.
Torque: 21 N Vm (210 kgf Vcm, 15 ft Vlbf)
(c) Connect the check connector and harness protector
with the two bolts to the air intake chamber.
(d) Install the six nuts and five bolts holding the intake air connector to the air intake chamber.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
(e) Connect the following hoses:
(1) Vacuum hose to brake booster union
(2) Air hose (to charcoal canister)
(3) Vacuum hose from vacuum pipe
(4) Vacuum sensing hose
(5) Air hose (to PS air control valve)
2. INSTALL EGR PIPE (a) Install a gasket and the EGR pipe with the two bolts.
Torque: 21 N Vm (210 kgf Vcm, 15 ft Vlbf)
(b) Tighten the union nut.
Torque: 64 N Vm (650 kgf Vcm, 47 ft Vlbf)
±
EFI SYSTEMFI±61Air Induction System (Acoustic Control Induction System (ACIS)
WhereEverybodyKnowsYourName

3. INSTALL NO.2 VACUUM PIPEInstall the vacuum pipe with the two nuts.
Torque: 21 N Vm (210 kgf Vcm, 15 ft Vlbf)
4. INSTALL OIL DIPSTICK FOR ENGINE
5. INSTALL VACUUM TANK AND VSV
(a) Install the VSV with the screw on the vacuum tank.
Torque: 8.8 N Vm (90 kgf Vcm, 78 in. Vlbf)
(b) Install the vacuum hose.
6. INSTALL VACUUM CONTROL VALVE SET (a) Install the vacuum control valve set with the two nuts.
Torque: 21 N Vm (210 kgf Vcm, 15 ft Vlbf)
(b) Connect the following hoses:
(1) Vacuum hose to VSV
(2) Vacuum hose to vacuum pipe
(c) Connect the connector to the VSV.
7. (A/T) INSTALL DIPSTICK GUIDE FOR TRANSMISSION
(a) Install a new O±ring on the dipstick guide.
(b) Apply soapy on the O±ring.
(c) Connect the dipstick guide end to the tube of the oil pan,
and install the dipstick guide with the bolt.
(d) Install the dipstick.
8. CONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
FI±62
±
EFI SYSTEM
Air Induction System (Acoustic Control Induction System (ACIS)
WhereEverybodyKnowsYourName