1991 LEXUS SC400 engine

SERVICE SPECIFICATIONS
SERVICE DATA
 Engine tune±up Battery specific gravity  1.27±1.29 g  (when fully charged at 205C (68 5F))  High±tension cord resistance Limit 25 k
per cord  Valve clearance Intake 0.15 ± 0.25 mm 0.006 ± 0.010 in.   Exhaust 0.25 ± 0.35 mm 0.010 ± 0.014 in.
  Ignition timing 8±12 5 BTDC @ idle
   (w/ Terminals TE1 and E1 connected)
  Idle speed 700 + 50 rpm
 


Intake
manifold 


at Idle speed 


 


60 kPa 450 mmHg 17.7 in.Hg
vacuum vacuum  
Compressionat 250 rpmSTD1,226 kPa (12.5 kgf/cm, 178 psi) or more pressure  Limit 981 kPa 10.0 kgf/cm 142 psi  Difference of pressure between each cylinder 98 kPa (1.0 kgf/cm, 14 psi) or less Timing belt ten- Protrusion from housing end 10.5 ± 11.5 mm 0.413 ± 0.453 in. g
sioner g  
 Cylinder head Warpage Cylinder block side Limit 0.10 mm 0.0039 in.
 
y
 Manifold side Limit 0.10 mm 0.0039 in.
  Valve seat Refacing angle 30
5, 45 5, 75 5
  Contacting angle 455
Contacting width1.0 ± 1.4 mm0.039 ± 0.055 in.  Cylinder head bolt thread outside diam4eter 
   STD 9.770 ± 9.960 mm 0.3846 ± 0.3921 in.   Limit 9.60 mm 0.3780 in. Valve guide Inside diameter 6.010 ± 6.030 mm 0.2366 ± 0.2374 in.
 
g
bushing Outside diameter (for repair part) STD 11.048 ± 11.059 mm 0.4350 ± 0.4354 in.
 
g
  O/S 0.05 11.098 ± 11.109 mm 0.4369 ± 0.4374 in.
 Valve Valve overall length STD Intake 94.95 mm 3.7382 in.
    Exhaust 96.90 mm 3.8150 in.
LimitIntake94.45 mm3.7185 in.    Exhaust 96.40 mm 3.7953 in.  Valve face angle   44.5 5  Stem diameter  Intake 5.970 ± 5.985 mm 0.2350 ± 0.2356 in.    Exhaust 5.965 ± 5.980 mm 0.2356 ± 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.
Exhaust0.10 mm0.0039 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. g 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±1.2195 in.
  Lifter bore diameter  31.000±31.016 mm 1.2205±1.2211 in.
Oil clearanceSTD0.024±0.050 mm0.0009±0.0020 in.   Limit 0.07 mm 0.0028 in.
EM±178±
ENGINE MECHANICAL Service Specifications
WhereEverybodyKnowsYourName

SERVICE DATA (Cont'd)
 Camshaft Thrust clearance STD 0.040±0.090 mm 0.0016±0.0035 in.
   Limit 0.12 mm 0.0047 in.
  Journal oil clearance 
   STD Exhaust camshaft thrust portion 0.025±0.061 mm 0.0010±0.0024 in.
   Others 0.030±0.067 mm 0.0012±0.0026 in.
Limit0.10 mm0.0039 in.  Journal diameter 
   Exhaust camshaft thrust portion 23.959±23.975 mm 0.9433±0.9439 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 backlash STD 0.020±0.200 mm 0.0008±0.0079 in.
Limit0.30 mm0.0188 in.  Camshaft gear spring end free distance 18.2±18.8 mm 0.712±0.740 in. Manifold Warpage Limit Intake 0.15 mm 0.0059 in.   Exhaust 1.00 mm 0.0394 in. Air intake Warpage Limit 0.15 mm 0.0059 in. chamber  
 Cylinder block Cylinder head surface warpage Limit 0.07 mm 0.0028 in.
  Cylinder bore diameter STD 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.
   Limit 87.73 mm 3.4539 in.
  Main bearing cap stud bolt 
tension portion diameterSTD7.500±7.600 mm0.2953±0.2992 in.   
Limit
 
7.40 mm
 
0.2913 in. Piston and Piston diameter Mark 1 87.470±87.480 mm 3.4437±3.4441 in. piston ring  Mark 2 87.480±87.490 mm 3.4441±3.4445 in.   Mark 3 87.490±87.500 mm 3.4445±3.4449 in.  Piston oil clearance STD 0.020±0.040 mm 0.0008±0.0016 in.
   Limit 0.06 mm 0.0024 in.
  Piston ring groove clearance No.1 0.020±0.060 mm 0.0008±0.0024 in.
   No.2 0.015±0.055 mm 0.0006±0.0022 in.
  Piston ring end gap STD No.1 0.250±0.450 mm 0.0098±0.0177 in.
   No.2 0.350±0.600 mm 0.0138±0.0236 in.
   Oil 0.150±0.500 mm 0.0059±0.0197 in.
LimitNo.11.05 mm0.0413 in.   No.2 1.20 mm 0.0472 in.   Oil 1.10 mm 0.0433 in.
±
ENGINE MECHANICAL Service SpecificationsEM±179
WhereEverybodyKnowsYourName

SERVICE DATA (Cont'd)
 Connecting rod Thrust clearance STD 0.160±0.330 mm 0.0063±0.0114 in.
   Limit 0.35 mm 0.138 in.
  Connecting rod thickness 22.880±22.920 mm 0.9008±0.9024 in.
  Connecting rod bearing center wall thickness 
   Mark 2 1.484±1.487 mm 0.0584±0.0585 in.
Mark 31.487±1.490 mm0.0585±0.0587 in.   Mark 4 1.490±1.493 mm 0.0587±0.0588 in.   Mark 5 1.493±1.496 mm 0.0588±0.0589 in.   Mark 6 1.496±1.499 mm 0.0589±0.0590 in.   Mark 7 1.499±1.502 mm 0.0590±0.0591 in.
  Connecting rod oil clearance STD 0.027±0.053 mm 0.0011±0.0021 in.
   Limit 0.065 mm 0.0026 in.
  Rod bending Limit per 100 mm (3.94 in.) 0.05 mm 0.0020 in.
  Rod twist Limit per 100 mm (3.94 in.) 0.15 mm 0.0059 in.
  Connecting rod bushing inside diameter 22.005±22.017 mm 0.8663±0.8668 in.
Piston pin diameter21.997±22.009 mm0.8660±0.8665 in.  Connecting rod bushing oil clearance STD 0.005±0.011 mm 0.0002±0.0004 in.   Limit 0.05 mm 0.0020 in.  Connecting rod tension portion diameter 
   STD 7.200±7.300 mm 0.2835±0.2874 in.   Limit 7.00 mm 0.2756 in.
 Crankshaft Thrust clearance STD 0.020±0.220 mm 0.0008±0.0087 in.
   Limit 0.30 mm 0.0118 in.
  Thrust washer thickness STD 2.440±2.490 mm 0.0961±0.0980 in.
  Main journal bore diameter on cylinder block 67.026±67.033 mm 2.6388±2.6391 in.
  (with main bearing) 
Main journal oil clearanceSTD0.026±0.045 mm0.0010±0.0018 in.   
Limit
 
0.055 mm
 
0.0022 in.  Main journal diameter 66.988±67.000 mm 2.6373±2.6378 in.  Main bearing center wall thickness Mark 1 2.486±2.489 mm 0.0979±0.0980 in.   Mark 2 2.489±2.492 mm 0.0980±0.0981 in.   Mark 3 2.492±2.495 mm 0.0981±0.0982 in.
   Mark 4 2.495±2.498 mm 0.0982±0.0983 in.
   Mark 5 2.498±2.501 mm 0.0983±0.0985 in.
  Crank pin diameter 51.982±52.000 mm 2.0465±2.0472 in.
  Circle runout Limit 0.08 mm 0.0031 in.
  Main journal taper and out±of±round Limit 0.02 mm 0.0008 in.
Crank pin taper and out±of±roundLimit0.02 mm0.0008 in.
EM±180±
ENGINE MECHANICAL Service Specifications
WhereEverybodyKnowsYourName

TORQUE SPECIFICATIONS
\
 \
Part tightened NVm kgf Vcm ft Vlbf
 No.1 idler pulley X Cylinder block  34 350 25
No.2 idler pulley X Cylinder block3435025 Hydraulic pump X Cylinder block 12 mm head 16 160 12  14 mm head 30 310 22
 Crankshaft pulley X Crankshaft  245 2,500 181
Camshaft timing pulley X Camshaft1081,10080 Timing belt tensioner X Oil pump  26 270 20 Spark plug X Cylinder head  18 180 13
 Drive belt tensioner X Cylinder block  16 160 12
Alternator X Alternator bracket3738027 Alternator X Cylinder block  37 380 27 Distributor housing X Cylinder head  18 185 13
 Distributor rotor X Distributor housing   3.8 39  34 in. Vlbf
Distributor cap X Camshaft timing pulley 3.839 34 in. Vlbf\
 \
RH No.2 timing belt cover X Cylinder block (for 12 mm head) 16 160 12 Drive belt idler pulley X Hydraulic pump  37 380 27
 A/C compressor X Hydraulic pump  49 500 36
A/C compressor X Cylinder block4950036 A/C compressor stay X Oil filter bracket  29 300 22 Exhaust manifold X Cylinder head  39 400 29
 Main oxygen sensor X Exhaust manifold  44 450 33
Cylinder head X Cylinder block1st3940029  2nd Turn 90 5  
 Camshaft bearing cap X Cylinder head  16 160 12
 Cylinder head cover X Cylinder head   5.9 60  52 in. Vlbf
Engine hanger X Cylinder head3738027 EGR pipe X Exhaust manifold  18 185 13 Rear water by±pass joint X Cylinder head  18 185 13
 Front water by±pass joint X Cylinder head  18 185 13
Intake manifold X Cylinder head1818513 Delivery pipe X Intake manifold  18 185 13\
 \
Fuel return pipe X RH delivery pipe(for union bolt) 35 360 26
 Fuel inlet hose X LH delivery pipe  39 400 29
for SST3334024 Cold start injector X Air intake chamber   7.8 80  69 in. Vlbf Air intake chamber X Intake manifold  18 185 13
 EGR pipe X Air intake chamber  18 185 13
EGR pipe X RH cylinder head1818513 Cold start injector tube X RH delivery pipe  15 150 11 Brake booster union X Air intake chamber  29 300 22
 Throttle body X Air intake chamber  18 185 13
ISC valve X Air intake chamber1818513 EGR valve adapter X Air intake chamber  18 185 13 EGR valve X EGR valve adapter  18 185 13
 Timing belt rear plate X Cylinder head   7.8 80  69 in. Vlbf
Water inlet housing X Water pump1818513\
 \
Catalytic converter (main) X Exhaust manifold 62 630 46\
 \
Catalytic converter (main) X Front exhaust pipe 43 440 32
\
 \
Front exhaust pipe support bracket X Transmission 43 440 32
PS pump X RH cylinder headBolt3940029  Nut 43 440 32 Main bearing cap X Cylinder block Nut 1st 27 275 20
  2nd Turn 90 5  
Bolt4950036
±
ENGINE MECHANICAL Service SpecificationsEM±181
WhereEverybodyKnowsYourName

TORQUE SPECIFICATIONS (Cont'd)
\
 \
Part tightened NVm kgf Vcm ft Vlbf
 Connecting rod cap X Connecting rod 1st 25 250 18
2ndTurn 90 5 Rear oil seal retainer X Cylinder block   7.8 80  69 in. Vlbf Water seal plate X Cylinder block  14 145 10
 Alternator bracket X Cylinder block  18 185 13
 Oil pump X Cylinder block 12 mm head 16 160 12
14 mm head3031022 Water pump X Cylinder block  18 185 13 Water by±pass pipe X Cylinder block  18 185 13
 Knock sensor X Cylinder block  44 450 33
 Starter X Cylinder block  39 400 29
Engine mounting bracket X Cylinder block3738027 Drive plate X Crankshaft  98 1,000 72 A/T oil cooler pipe X Transmission  34 350 25 Rear engine mounting member X Body  25 260 19
\
 \
Rear engine mounting member X Engine mounting insulator 13 135 10
\
 \
Front engine mounting insulator X Suspension crossmember 59 600 43
Center floor brace X Body131309 Tailpipe X Center exhaust pipe  43 440 32 Front exhaust pipe X Center exhaust pipe  43 440 32
 Sub±oxygen sensor X Front exhaust pipe  44 450 33
EM±182±
ENGINE MECHANICAL Service Specifications
WhereEverybodyKnowsYourName

The EFI system is composed of three basic sub±systems: Fuel, Air Induction and Elect\
ronic Control
Systems.
FUEL SYSTEM
An electric pump fuel pressure supplies sufficient fuel, under a constant pressure, to the EFI injectors. In
accordance with signals from the ECU (Electronic Control Unit), these \
injectors inject the quantity of fuel most
appropriate for the engine condition into the intake manifold.
AIR INDUCTION SYSTEM
The air induction system provides sufficient air for engine operation.
ELECTRONIC CONTROL SYSTEM
The 1UZ±FE engine (ECU±formerly EFI computer) with a microcomputer \
centrally controls the EFI, ESA,
ISC and Diagnosis system, etc. The ECU controls the following functions:
1. Electronic Fuel Injection (EFI)
The ECU receives signals from various sensors indicating changing engine op\
eration conditions such as:Intake air volume
Intake air temperature
Coolant temperature
Engine rpm
Acceleration/deceleration
Exhaust oxygen content etc.
The signals are utilized by the ECU to determine the injection duration nec\
essary for an optimum air±fuel
ratio.
2. Electronic Spark Advance (ESA) The ECU is programmed with data for optimum ignition timing under any and all opera\
ting conditions. Using
data provided by sensors which monitor various engine functions (rpm, coola\
nt temperature, etc.), the
Electronic Control Unit (ECU) triggers the spark at precisely right instant. (S\
ee IG section)
3. Idle Speed Control (ISC) The ECU is programmed with idle speed data for various engine conditions (\
coolant temperature, air condi-
tioner ON/OFF, etc.).
The air volume flowing through the throttle valve by±pass passage is adj\
usted according to the signal from
each sensor and the idle speed is kept at the set value.
4. Diagnosis Function When the ECU detects any malfunctions or abnormalities in the sensor network\
, it lights the ºCHECKº en-
gine warning light in the combination meter. At the same time, the trouble is identified and a diagnostic code
is recorded by the ECU. The diagnostic code can be read by the number of\
blinks of the ºCHECKº engine
warning light when terminals TE1 and E1 are connected. The diagnostic co\
des are refer to the later page.
(See TR section)
5. Self±Correction Function If any sensor malfunctions, an average value recorded in the back±up ci\
rcuit is substituted to make driving
possible.
If danger is predicted, the engine is stopped and the ºCHECKº engine\
warning light will light up.
6. Fail±Safe Function Even if an abnormality occurs in the ECU, the back±up circuit uses a specifie\
d fuel injection and ignition
timing to provide vehicle driveability, and also lightsup the ºCHECKº engine warning light.
FI±4
EFI SYSTEM
± Description
WhereEverybodyKnowsYourName

FUEL SYSTEM
Fuel is pumped up by the fuel pump, which flows through the fuel filter under pr\
essure through the fuel pipe
to the delivery pipe where it is distributed to each injector and the cold\
start injector.
The fuel pressure regulator adjusts the pressure of the fuel from the fuel \
line (high pressure side) to a pres-
sure 284 kPa (2.9 kgf/cm
2, 41 psi) higher than the pressure inside the intake manifold, and exce\
ss fuel is re-
turned to the fuel tank through the return pipe.
When the engine is hot, the fuel pressure is increased to control percolatio\
n in the fuel system and improve
restartability and idling stability.
The pulsation damper absorbs the slight fluctuations in fuel pressure ca\
used by the injector.
The injectors operate on input of injection signals from the ECU and inj\
ect fuel into the intake manifold.
The cold start injector operates when starting with low coolant temperature or at normal temperature
ranges, injecting fuel into the air intake chamber to improve startability. FI±7
EFI SYSTEM
± Operation
WhereEverybodyKnowsYourName

AIR INDUCTION SYSTEM
Air filtered through the air cleaner passes through the air flow meter and \
the amount flowing to the air intake
chamber is determined according to the throttle valve opening in the throttle b\
ody and the engine rpm. Air flow meter measures the air intake flow to the engine by the swirl f\
requency.
Located in the throttle body is the throttle valve, which regulates the volume \
of air intake to the engine. Air
intake controlled by the throttle valve opening is distributed from the intake\
chamber to the manifold of each
cylinder and is drain into the combustion chamber. At air low temperature the ISC valve opens and the air flows through the I\
SC valve, as well as the throttle
body, into the air intake chamber. During engine warming up, even if the throttle valve is completely clo\
sed, air
flows to the air intake chamber, thereby increasing the idle speed (first idle operation). The air intake chamber prevents pulsation of the intake air, reduces the influence on the air flow meter and
increases the air intake volume. It also prevents intake air interference in each\
cylinder. FI±8
EFI SYSTEM ± Operation
WhereEverybodyKnowsYourName