1991 LEXUS SC400 check engine

2. INSPECT AND CLEAN AIR FILTER
(a) Visually check that the air filter is not excessively damagedor only.
If necessary, replace the air filter.
(b) Clean the air filter with compressed air. First blow from the inside thoroughly, then blow off the out-
side of the air filter.
3. REINSTALL AIR FILTER
EG1KB±02
HIGH±TENSION CORDS INSPECTION
1. REMOVE NO.3 TIMING BELT COVERS (See steps 10 to 14 on pages EG±16)
2. REMOVE HIGH±TENSION CORDS (See step 1 on page IG±16)
NOTICE: Pulling on or bending the cords may damage the con-
ductor inside.
3. INSPECT HIGH±TENSION CORD RESISTANCE Using an ohmmeter, measure the resistance.
Maximum resistance:
25 k
per cord
If the resistance is greater than maximum, replace the cord.
4. REINSTALL HIGT±TENSION CORDS (See step 1 on page IG±19)
5. REINSTALL NO.3 TIMING BELT COVERS (See steps 28 to 30 on pages EG±29)
EG±12
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EG0EY±02
DRIVE BELT INSPECTION
INSPECT DRIVE BELT
HINT: A belt tensioner is used, so checking the belt tension
is not necessary.
(a) Visually check the belt for excessive wear, frayed cords etc. If necessary, replace the drive belt.
HINT:
wCracks on the rib side of a belt are considered
acceptable. If the drive belt has chunks missing from the
ribs, it should be replaced.
w The drive belt tension can be released by turning the the
belt tensioner counterclockwise. The pulley bolt for the
belt tensioner has a left±hand thread.
(b) Check the belt tensioner operation. wCheck that the belt tensioner moves downward when
the drive belt is pressed down at the points indicated in
the illustration with approx. 98 N (10 kgf, 22.0 lbf) of
force.
w Check the ali gnment of the belt tensioner pulley to make
sure the drive belt will not slip off the pulley.
If necessary, replace the belt tensioner.
w Check that the arrow mark on the belt tensioner falls
within area A of the scale.
If it is outside area A, replace the drive belt.
HINT:
w When a new belt is installed, it should lie within area B.
If not, the drive belt is not correct.
w After installing a belt, check that it fits properly in the
ribbed grooves.
w Check by hand to confirm that the belt has not slipped
out of the groove on the bottom of the pulley.
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(h) Disconnect the 2 engine wire connectors.
(i) Remove the 8 bolts, seal washers, cylinder head cover andgasket.
19. SET NO.1 CYLINDER TO TDC/COMPRESSION
(a) Turn the crankshaft pulley, and align its groove with timing mark ª0º of the No.1 timing belt cover.
(b) Check that the timing marks of the camshaft timing pulleys and timing belt rear plates aligned.
If not, turn the crankshaft 1 revolution (360 5) and align the
mark as above.
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20. INSPECT VALVE CLEARANCE
(a) Check only the valves indicated.wUsing a feeler gauge, measure the clearance between
the valve lifter and camshaft
w Record the out±of±specification valve clearance
measurements. They will be used later to determine the
required replacement adjusting shim.
Valve clearance (Cold):
Intake0.15 ± 0.25 mm (0.006 ± 0.010 in.)
Exhaust 0.25 ± 0.35 mm (0.010 ± 0.014 in.)
(b) Turn the crankshaft 1 revolution (360
) and align the mark as
above. (See procedure in step 8)
(c) Check only the valves indicated as shown. Measure the valve
clearance. (See procedure in step (a))
21. REMOVE THEFT DETERRENT HORN
(a) Disconnect the connector.
(b) Remove the bolt and theft deterrent horn. HINT: Remove the deterrent horn when the valve clearance
is adjusted for the front portion of the exhaust camshaft on
the LH cylinder head.
EG±20
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(b) Determine the replacement adjusting shim size by followingthe Formula or Charts:
wUsing a micrometer, measure the thickness of the
removed shim.
w Calculate the thickness of a new shim so that the valve
clearance comes within specified value.
T 000 Thickness of removed shim
A 000 Measured valve clearance
N 000 Thickness of new shim
Intake:
N = T + (A ± 0.20 mm (0.008 in.))
Exhaust: N = T + (A ± 0.30 mm (0.012 in.))
w Select a new shim with a thickness as close as possible
to the calculated value.
HINT: Shims are available in 33 sized in increments of 0.025
mm (0.0010 in.) from 2.50 mm (0.0984 in.) to 3.30 mm
(0.1299 in.)
(c) Install a new adjusting shim. wPlace a new adjusting shim on the valve lifter.
w Using SST (A), press down the valve lifter and remove
SST (B).
SST 09248±05410, 09248±05021
(d) Recheck the valve clearance.
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40. RECONNECT NEGATIVE TERMINAL CABLE TOBATTERY
41. REFILL WITH ENGINE COOLANT
42. START ENGINE AND CHECK FOR LEAKS
EG21T±02
IGNITION TIMING INSPECTION
1. REMOVE UPPER HIGH±TENSION CORD COVER
(a) Remove the 2 bolts.
(b) Disconnect the front side claw groove of the upper cord cover
from the claw of lower cord cover, and remove the upper cord
cover.
2. WARM UP ENGINE Allow the engine to warm up to normal operating tempera-
ture.
3. CONNECT TACHOMETER AND TIMING LIGHT TO ENGINE
Connect the tester probe of a tachometer to terminal IG
of
the DLC1.
HINT: Set the tachometer to the 4±cylinder range.
NOTICE:
w Never allow the tachometer terminal to touch ground as
it could result in damage to the igniter and/or ignition
coil.
w As some tachometers are not compatible with this
ignition system, we recommend that you confirm the
compatibility of your unit before use.
4. INSPECT IGNITION TIMING
(a) Using SST, connect terminals TE1 and E1 of the DLC 1.
SST 09843±18020
EG±32
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(b) Connect the tester probe of a timing light to the high ±tension
cord for No.6 cylinder.
(c) Using a timing light, check the ignition timing.
Ignition timing: 8 ± 12 5 BTDC @ idle
(Transmission in neutral position)
If the ignition timing is not as specified, check that following
conditions are normal:
w Throttle valve fully closed
w Continuity between terminals IDL1 and E2 of the throttle
position sensor
w Valve timing
(d) Remove the SST from the DLC1. SST 09843±18020
5. DISCONNECT TACHOMETER AND TIMING LIGHT FROM ENGINE
6. REINSTALL UPPER HIGH±TENSION CORD COVER
(a) Fit portion A of the upper high±tension cord cover matching the top of the lower high±tension cord cover.
(b) Push the front side of the upper high±tension cord cover, and
fit the front side claw groove of the upper high±tension cord
cover to the claw of the lower high ±tension cord cover.
(c) Install the upper high±tension cord cover with the 2 bolts.
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EG115±06
IDLE SPEED INSPECTION
1. INITIAL CONDITIONS
(a) Engine at normal operating temperature
(b) Air cleaner installed
(c) All pipes and hoses of air induction system connected
(d) All accessories switched OFF
(e) All vacuum lines properly connectedHINT: All vacuum hoses for EGR system, etc. should be prop-
erly connected.
(f) MFI system wiring connectors fully plugged
(g) Ignition timing set correctly
(h) Transmission in neutral position
2. CONNECT TACHOMETER Connect the tester probe of a tachometer to terminal IG
of
the DLC1.
HINT: Set the tachometer to the 4±cylinder range.
NOTICE:
w Never allow the tachometer terminal to touch ground as
it could result in damage to the igniter and/or ignition
coil.
w As some tachometers are not compatible with this
ignition system, we recommend that you confirm the
compatibility of your unit before use.
3. INSPECT IDLE SPEED
(a) Race the engine speed at 2,500 rpm for approx. 90 seconds.
(b) Check the idle speed.
Idle speed:
700 + 50 rpm
If the idle speed is not as specified, check the IAC valve.
4. DISCONNECT TACHOMETER
EG±34
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