engine LEXUS SC400 1991 Service Repair Manual

EXHAUST GAS RECIRCULATION (EGR) SYSTEM
DESCRIPTION
To reduce NOx emission, part of the exhaust gases are recirculated through\
the EGR valve to the intake
manifold to lower the maximum combustion temperature.
OPERATION
Coolant Temp.ConditionEGR ValveExhaust Gas
Below 53 5C (127 5F)±CLOSEDNot recirculated
Above 55 5C (131 5F)(a)Idling, Deceleration, Neutral,
Low air volume, High Engine speedCLOSEDNot recirculatedAbove 55 C (131 F)
Except (a)OPEN*Recirculated
* The ECU calculates the appropriate number of steps according to the in\
take air volume and the engine speed, then
drives the stepping motor to maintain the EGR volume at a level appropri\
ate to the driving conditions.

±
EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) SystemEC±15
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INSPECTION OF EGR SYSTEM (USA
Spec.)
INSPECT SYSTEM OPERATION
(a) Using SST, connect terminals TE1 and E1 of the check(ºDIAGNOSISº) connector.
SST 09843±18020
(b) Keep the engine at 3,500 rpm.
(c) Set the transmission shift lever to the ºNº position.
(d) Remove the SST from the check connector.
SST 09843±18020
(e) Check whether the engine rpm increases 100±300 rpm under the following conditions.
Coolant temp.
Below 53 5C (127 5F) No increase
Above 55 5C (131 5F) Increases
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EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) SystemEC±17
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INSPECTION OF EGR SYSTEM
(Exc. USA Spec.)
1. CHECK AND CLEAN FILTERS IN EGR VACUUMMODULATOR
(a) Remove the cap and filter.
(b) Check the filter for contamination or damage.
(c) Using compressed air, clean the filters.
(d) Reinstall the filter and cap.
HINT: Install the filter with the coarser surface facing the at-
mospheric side (outward).
2. INSPECT SYSTEM OPERATION (a) Using SST, connect terminals TE1 and E1 of the check
(ºDIAGNOSISº) connector.
SST 09843±18020
(b) Keep the engine at 3,500 rpm.
(c) Set the transmission shift lever to the ºNº position.
(d) Remove the SST from the check connector.
SST 09843±18020
(e) Check whether the engine rpm increases 100±300 rpm under the following conditions:
Coolant temp.
Below 53 5C (127 5F) No increase
Above 55 5C (131 5F) Increases
EC±18
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EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) System
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(b) Apply battery voltage across the terminals.
(c) Check that the air flows from port E to the filter.
If operation is not as specified, replace the VSV.
4. REINSTALL VSV (a) Install the VSV with the bolt.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
(b) Connect the following hoses:
(1) Vacuum hose (from EGR valve) to VSV
(2) Vacuum hose (from EGR vacuum modulator) to VSV
(c) Connect the VSV connector.
5. RECONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
INSPECTION OF EGR VACUUM
MODULATOR (Exc. USA Spec.)
1. DISCONNECT VACUUM HOSES FROM EGR VACUUMMODULATOR
Disconnect the three vacuum hoses from ports P, Q and R of
the EGR vacuum modulator.
2. INSPECT EGR VACUUM MODULATOR OPERATION (a) Block ports P and R with your finger.
(b) Blow air into port Q, and check that the air passesthrough to the air filter side freely.
(c) Start the engine, and maintain speed at 2,500 rpm.
(d) Repeat the above test. Check that there is a strong resistance to air flow.
3. RECONNECT VACUUM HOSES TO EGR VACUUM MODULATOR
Connect the three vacuum hoses to the proper locations.
EC±20
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EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) System
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INSPECTION OF EGR VALVE
(USA Spec.)
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and the negative (±) termi-
nal cable is disconnected from the battery.
2. DISCONNECT EGR VALVE CONNECTOR
3. INSPECT EGR VALVE RESISTANCE Using an ohmmeter, measure the resistance between termi-
nal B1 (or B2) and other terminals (S1, S2, S3 and S4).
Resistance (Cold): 19.9±23.4

4. DRAIN ENGINE COOLANT (See page CO±6)
5. REMOVE EGR VALVE (a) Disconnect the following hoses:(1) Water by±pass hose (from ISC valve) from the EGR
valve
(2) Water by±pass hose (from rear water by±pass joint) from the EGR valve
(b) Remove the two nuts, EGR valve and gasket.
6. INSPECT EGR VALVE
A. Visually inspect EGR valve Check for sticking and heavy carbon deposits.
If a problem is found, replace the EGR valve assembly.
EC±22
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EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) System
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(b) Install the EGR valve with the two nuts.
Torque: 18 NVm (185 kgf Vcm, 13 ft Vlbf)
(c) Connect the following hoses:
(1) Water by±pass hose (from ISC valve) to the EGR valve
(2) Water by±pass hose (from rear water by±pass joint) to the EGR valve
8. RECONNECT EGR VALVE CONNECTOR
9. RECONNECT CABLE TO NEGATIVE TERMINAL OF BATTERY
10. REFILL WITH ENGINE COOLANT (See page CO±7)
INSPECTION OF EGR VALVE
(Exc. USA Spec.)
1. DRAIN ENGINE COOLANT (See page CO±6)
2. REMOVE EGR VALVE (a) Disconnect the following hoses:(1) Vacuum hose (from VSV) from EGR valve
(2) Vacuum hose (from VSV) from EGR vacuum
modulator
(3) Vacuum hose (from EGR vacuum modulator) f rom EGR valve
(4) Water by±pass hose (from ISC valve) from the
EGR valve
(5) Water by±pass hose (from rear water by±pass joint) from the EGR valve
(b) Disconnect the vacuum modulator bracket from the
EGR valve.
(c) Remove the two nuts, EGR valve and gasket.
EC±24
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EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) System
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3. INSPECT EGR VALVECheck for sticking and heavy carbon deposits.
If a problem is found, replace the EGR valve assembly.
4. REINSTALL EGR VALVE (a) Place a new gasket on the EGR valve adaptor.
NOTICE:
w Do not touch the adaptor and EGR valve surfaces of the
gasket with your hand.
w Align the port holes of the gasket and adaptor.
Be careful of the installation direction.
(b) Install the EGR valve with the two nuts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
(c) Install the vacuum modulator bracket to the EGR valve.
(d) Connect the following hoses:
(1) Vacuum hose (from VSV) to EGR valve
(2) Vacuum hose (from VSV) to EGR vacuum modula- tor
(3) Vacuum hose (from EGR vacuum modulator) to EGR valve
(4) Water by±pass hose (from ISC valve) to the EGR
valve
(5) Water by±pass hose (from rear water by±pass joint) to the EGR valve
5. REFILL WITH ENGINE COOLANT (See page CO±7)
±
EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) SystemEC±25
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SERVICE SPECIFICATIONS
SERVICE DATA
EG065±0A Tune±up Battery specific gravity  1.27±1.29
    (when fully charged at 205C (68 5F))
  High±tension cord resistance Limit 25 k
per cord
  Valve clearance (Cold) Intake 0.15±0.25 mm (0.006±0.010 in.)
   Exhaust 0.25±0.35 mm (0.010±0.014 in.)
Valve clearance adjusting shimNo.012.500 mm (0.0984 in.)   No.62 2.525 mm (0.0994 in.)   No.63 2.550 mm (0.1004 in.)   No.64 2.575 mm (0.1014 in.)   No.06 2.600 mm (0.1024 in.)
   No.65 2.625 mm (0.1033 in.)
   No.66 2.650 mm (0.1043 in.)
   No.67 2.675 mm (0.1053 in.)
   No.13 2.700 mm (0.1063 in.)
   No.68 2.725 mm (0.1073 in.)
   No.18 2.750 mm (0.1083 in.)
No.192.775 mm (0.1093 in.)   No.23 2.800 mm (0.1102 in.)   No.70 2.825 mm (0.1112 in.)   No.28 2.850 mm (0.1122 in.)   No.71 2.875 mm (0.1132 in.)
   No.33 2.900 mm (0.1142 in.)
   No.72 2.925 mm (0.1152 in.)
   No.38 2.950 mm (0.1161 in.)
   No.73 2.975 mm (0.1171 in.)
   No.43 3.000 mm (0.1181 in.)
No.743.025 mm (0.1191 in.)   No.48 3.050 mm (0.1201 in.)   No.75 3.075 mm (0.1211 in.)   No.51 3.100 mm (0.1220 in.)   No.76 3.125 mm (0.1230 in.)   No.77 3.150 mm (0.1240 in.)
   No.78 3.175 mm (0.1250 in.)
   No.56 3.200 mm (0.1260 in.)
   No.79 3.225 mm (0.1270 in.)
   No.80 3.250 mm (0.1280 in.)
   No.81 3.275 mm (0.1289 in.)
No.613.300 mm (0.1299 in.)  Ignition timing  8 ± 12 5 BTDC @ idle 


 


 


 

(w/ Terminals TE1 and E1 connected
of DLC1)
  Idle speed  700
+ 50 rpm
 Intake at idle speed  60 kPa (450 mmHg. 17.7 in.Hg)
 manifold
 vacuum   
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Compression at 250 rpm STD 1,226 kPa (12.5 kgf/cm2, 178 psi) or
more
 pressureLimit 981 kPa (10.0 kgf/cm2, 142 psi)  Difference of pressure between each cylinder  98 kPa (1.0 kgf/cm2, 14 psi) or less 

Timing belt
tensionerProtrusion from housing end10.5±11.5 mm (0.413±0.453 in.)
 Cylinder head Warpage Limit 0.10 mm (0.039 in.)
  Valve seat  
  Refacing angle  30
5, 45 5, 75 5
  Contacting angle  455
  Contacting width  1.0±1.4 mm (0.039±0.055 in.)
  Cylinder head bolt thread inside diameter STD 9.770±9.960 mm (0.3846±0.3921 in.)
   Limit 9.60 mm (0.3780 in.)
 Valve guideInside diameter6.010±6.030 mm (0.2366±0.2374 in.)
 bushing Outside diameter (for repair part) STD 11.048±11.059 mm (0.4350±0.4354
in.)
 O/S 0.05 11.098±11.109 mm (0.4369±0.4374 in.) ValveValve overall lengthSTD (Intake)94.95 mm (3.7382 in.)   (Exhaust) 96.90 mm (3.8150 in.)   Limit (Intake) 94.45 mm (3.7185 in.)   (Exhaust) 96.40 mm (3.7953 in.)
  Vale face angle  44.55
  Stem diameter Intake 5.970±5.985 mm (0.2350±0.2356 in.)
   Exhaust 5.965±5.980 mm (0.2348±0.2354 in.)
  Stem oil clearance STD (Intake) 0.025±0.060 mm (0.0010±0.0024 in.)
   (Exhaust) 0.030±0.065 mm (0.0012±0.0026 in.)
   Limit (Intake) 0.08 mm (0.0031 in.)
   (Exhaust) 0.10 mm (0.0039 in.)
  Margin thickness STD 1.0 mm (0.039 in.)
   Limit 0.5 mm (0.020 in.)
 Valve spring Squareness Limit 2.0 mm (0.079 in.)
  Free length  43.6 mm (1.717 in.)
  Installed tension at 32.9 mm (1.295 in.)  186±206 N (19.0±21.0 kgf, 41.9±46.3
lbf)
 

Valve lifter 

Lifter diameter 


 

30.966±30.976 mm (1.2191±2.2195
in.)
 


 


Lifter bore diameter 


 


31.000±31.016 mm (1.2205±1.2211
in.)
  Oil clearance STD 0.024±0.050 mm (0.0009±0.0020 in.)
   Limit 0.07 mm (0.0028 in.)
EG±206±
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Camshaft Thrust clearance STD 0.040±0.090 mm (0.0016±0.0035 in.)
   Limit 0.12 mm (0.0047 in.)
  Journal oil clearance  
  Exhaust camshaft thrust portion STD 0.025±0.061 mm (0.0010±0.0024 in.)  
Others
 
STD
 
0.030±0.067 mm (0.0012±0.0026 in.)   
Limit
 
0.10 mm (0.0039 in.)  Journal diameter  
  Exhaust camshaft thrust portion  23.959±23.975 mm (0.9433±0.9539 in.)  Others  26.954±26.970 mm (1.0612±1.0618 in.)  Circle runout Limit 0.08 mm (0.0031 in.)  Cam lobe height STD (Intake) 41.710±41.810 mm (1.6421±1.6461 in.)   (Exhaust) 41.910±42.010 mm (1.6500±1.6539 in.)   Limit (Intake) 41.56 mm (1.6362 in.)
   (Exhaust) 41.76 mm (1.6441 in.)
  Camshaft gear backslash STD 0.020±0.200 mm (0.0008±0.0079 in.)
   Limit 0.30 mm (0.0188 in.)
  Camshaft gear spring end free distance  18.2±18.8 mm (0.712±0.740 in.)
 Air intake Warpage Limit 0.15 mm (0.0059 in.)
 chamber
 Manifold Warpage Limit (Intake) 0.15 mm (0.0059 in.)
   (Exhaust) 1.00 mm (0.0394 in.)
 Cylinder block Cylinder head surface warpage Limit 0.07 mm (0.0028 in.)
  Cylinder bore±diameter Mark 1 87.500±87.510 mm (3.4449±3.4453 in.)
   Mark 2 87.510±87.520 mm (3.4453±3.4457 in.)
   Mark 3 87.520±87.530 mm (3.4457±3.4461 in.)
Limit87.73 mm (3.4539 in.)  
Main journal bore diameter (Reference)
 
Mark 00
 
72.000 mm (2.8346 in.)   Mark 01 72.001 mm (2.8347 in.)   Mark 02 72.002 mm (2.8347 in.)   Mark 03 72.003 mm (2.8348 in.)   Mark 04 72.004 mm (2.8348 in.)   Mark 05 72.005 mm (2.8348 in.)   Mark 06 72.006 mm (2.8349 in.)   Mark 07 72.007 mm (2.8349 in.)
   Mark 08 72.008 mm (2.8350 in.)
   Mark 09 72.009 mm (2.8350 in.)
   Mark 10 72.010 mm (2.8350 in.)
   Mark 11 72.011 mm (2.8351 in.)
   Mark 12 72.012 mm (2.8351 in.)
   Mark 13 72.013 mm (2.8352 in.)
   Mark 14 72.014 mm (2.8352 in.)
   Mark 15 72.015 mm (2.8352 in.)
   Mark 16 72.016 mm (2.8353 in.)
 Main bearing cap stud bolt tension portion diameter
   STD 7.500±7.600 mm (0.2953±0.2992 in.)
   Limit 7.40 mm (0.2913 in.)
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