Engine Controls - Adjustments Lexus ES XV10

ENGINE MECHANICAL

Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.

Scheme 1

Scheme 2

Scheme 3

Scheme 4

1. With engine cold, disconnect negative battery cable. Drain engine coolant. On automatic transmission models, disconnect throttle cable from throttle linkage. Disconnect accelerator cable from throttle linkage.
2. Disconnect airflow meter connector and air hoses. Disconnect coil cord clamp. Loosen air cleaner hose clamp bolt. Release air cleaner cover clips. Remove air cleaner cap and airflow meter together with air cleaner hose.
3. With a 5-mm hex-wrench, remove the center valley cover. On California cars, disconnect the EGR gas temperature sensor connector clamp from the emission control valve set. Disconnect vacuum hoses from fuel pressure VSV and IACV VSV. Disconnect VSV connectors. Remove the 2 bolts and emission control set.
4. Disconnect brake booster vacuum hose. Disconnect P/S air hose. Disconnect PCV hose. Disconnect IAVC vacuum hose. Remove nut and disconnect the 2 ground straps. Disconnect cold start injector connector. Disconnect cold start injector pipe (No. 2 fuel pipe). Ensure spilled fuel from union is caught with a shop towel.
5. Remove 2 bolts and engine hanger. Remove 2 bolts and disconnect air intake chamber stay. Disconnect and remove EGR pipe. Remove bolt and disconnect hydraulic pressure pipe from air intake chamber. Disconnect 3 emission control vacuum hoses. Disconnect 2 water by-pass hoses. On California vehicles, disconnect EGR gas temperature sensor connector. Disconnect TPS connector. Disconnect ISC valve connector. Disconnect ISC valve air hose. Disconnect P/S air hose. Remove air intake chamber bolts (2) and nuts (2), and remove air intake chamber and gasket.
6. To disconnect LH engine wire harness: disconnect 3 injector connectors, engine oil level sensor connector, oil pressure switch connector and A/C compressor connector. Disconnect alternator connector and wire. Disconnect water temperature sensor connector (for hydraulic cooling fan). Remove the 2 bolts, and disconnect the 5 clamps and LH engine wire harness.
7. To disconnect RH engine wire harness: disconnect 3 injector connectors, water temperature sender gauge connector, O2 sensor connector and P/S pump connector. Remove the 2 bolts and disconnect the 2 clamps and RH engine wire harness. Remove the cylinder head cover nuts and seal washers, and remove the cylinder head covers.
8. Rotate crankshaft pulley and align pulley groove with "0" mark on timing belt cover to position No. 1 cylinder at TDC of compression stroke. Ensure cylinder No. 1 intake valve lifters are loose and exhaust valve lifters are tight. If not, rotate crankshaft 360 degrees and realign timing marks. (Scheme 1)
9. Measure and record clearance of intake valves on cylinders No. 1 and 6, and exhaust valves on cylinders No. 2 and 3. Rotate crankshaft pulley 240 degrees (2/3 of a revolution). Measure and record clearance of intake valves on cylinders No. 2 and 3, and exhaust valves on cylinders No. 4 and 5. (Scheme 2)
10. Rotate crankshaft pulley another 240 degrees (2/3 of a revolution). Measure and record clearance of intake valves on cylinders No. 4 and 5, and exhaust valves on cylinders No. 1 and 6. (Scheme 3)
11. Determine if clearance is within specification. See «VALVE CLEARANCE SPECIFICATIONS TABLE (ES300)»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments). If clearance adjustment is required, rotate crankshaft pulley to position lobe upward on valve to be adjusted.
12. Use Valve Clearance Adjuster (SST 09248-55011) to press valve lifter downward. Prior to pressing lifter downward, position adjustment shim notch area toward spark plug.
13. Press valve lifter downward using SST (A), install SST (B) between camshaft and valve lifter and remove SST (A). (Scheme 4) Using a small screwdriver and magnet, remove adjusting shim.
14. Using a micrometer, measure thickness of shim just removed. Select a new shim that will give correct valve clearance. See «VALVE CLEARANCE SPECIFICATIONS TABLE (ES300)»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments). Shims are available in thicknesses of.0984-.1299" (2.50-3.30 mm) in.002" (.05 mm) increments.
15. Install proper shim. Using SST (A), press downward on valve lifter and remove SST (B). Recheck valve clearance. For installation, reverse removal procedure. Install air intake chamber using new gaskets. Tighten air intake chamber bolts to 32 ft. lbs. (43 N.m) and EGR pipe to 58 ft. lbs. (78 N.m). Install remaining components.
16. Air must be bled from cooling system while filling. To bleed air from cooling system, open union bolt (bolt closest to upper radiator hose on radiator hose outlet on intake manifold) approximately 5 revolutions. Fill cooling system, and tighten union bolt to 13 ft. lbs. (18 N.m).

VALVE CLEARANCE SPECIFICATIONS

Scheme 5

Scheme 6

1. With engine cold, disconnect negative battery cable and drain coolant. Remove air duct and dust covers. Remove 2 bolts, nut and throttle body cover. Remove air hose from IAC valve. Remove hose from power steering air control valve. Remove 2 bolts, disconnect air connector pipe from throttle body and remove air connector pipe.
2. Remove 2 bolts and disconnect front claw groove of upper cover from claw of lower cover. Remove upper high tension wire cover. Disconnect PCV hose from PCV valve on left cylinder head. Remove 3 bolts and wire cover. Remove 4 bolts, right timing belt cover and 3 gaskets.
3. Disconnect vacuum hose from EVAP-BVSV. Remove 4 bolts and disconnect wire grommet from left timing belt cover. Remove timing belt cover and 3 gaskets. Disconnect spark plug wires from spark plugs. Remove spark plugs. Remove bolt and spark plug wire clamp. Remove 4 clamps.
4. Disconnect throttle body sensor connectors. Disconnect water by-pass pipe (rear water by-pass joint) from clamp on engine wire cover. Disconnect water by-pass pipe from hose. Remove 2 bolts and 2 nuts, disconnect PCV hose from cylinder head cover and remove throttle body with gasket.
5. Disconnect engine wire from wire bracket on right cylinder head. Remove engine wire bracket. Remove bolt and pull out dipstick guide with dipstick. Remove both cylinder head covers.
6. Turn crankshaft pulley and align its groove with "0" timing mark on No. 1 timing belt cover. Ensure that timing marks of camshaft pulleys and timing belt rear plates are aligned. If not, rotate crankshaft one revolution (360 degrees) and align marks again. (Scheme 5)
7. Measure and record clearance of intake valves on cylinders No. 1, 2, 5, 7 and 8, and exhaust valves on cylinders No. 1, 4 and 8. Rotate crankshaft pulley 360 degrees (1 revolution) and align timing marks. Measure and record clearance of intake valves on cylinders No. 3, 4 and 6, and exhaust valves on cylinders No. 2, 3, 5, 6 and 7. (Scheme 6)
8. Determine if clearance is within specification. See «VALVE CLEARANCE SPECIFICATIONS TABLE (LS400 & SC400)»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments). If clearance adjustment is required, rotate crankshaft pulley to position lobe upward on valve to be adjusted.
9. Use Valve Clearance Adjuster (SST 09248-55011) to press valve lifter downward. Press valve lifter downward using SST (A), install SST (B) between camshaft and valve lifter and remove SST (A). Using compressed air and magnet, remove adjusting shim by blowing air into shim hole. (Scheme 4)
10. Using a micrometer, measure thickness of shim just removed. Select a new shim that will give correct valve clearance. See «VALVE CLEARANCE SPECIFICATIONS TABLE (LS400 & SC400)»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments). Shims are available in thicknesses of.0984-.1299" (2.50-3.30 mm) in.002" (.05 mm) increments.
11. Install proper shim. Using SST (A), press downward on valve lifter and remove SST (B). Recheck valve clearance. Reinstall cylinder head covers using new gaskets. Tighten cylinder head cover bolts to 52 INCH lbs. (5.9 N.m). Install remaining components. Fill cooling system and check for leaks.

VALVE CLEARANCE SPECIFICATIONS

Scheme 7

Scheme 8

Scheme 9

Scheme 10

1. With engine cold, turn ignition switch to LOCK and disconnect negative battery cable. Disconnect accelerator cable. On A/T models, disconnect throttle control cable. On all models, disconnect cruise control actuator cable.
2. Disconnect P/S air hose from No. 4 timing belt cover. Disconnect PCV hose from No. 2 cylinder head cover. Remove air cleaner hose. Remove EGR pipe and gasket. Remove 4 nuts and throttle body bracket.
3. Disconnect PCV hose, 3 vacuum hoses and VSV (for EGR). Disconnect TPS connector and ISC valve connector. Disconnect sub-TPS sensor connector and sub-throttle actuator connector. Disconnect EGR gas temperature sensor connector.
4. Remove 4 bolts and 2 nuts holding intake air connector to intake chamber. Remove VSV nut. Disconnect the 2 water by-pass hoses from throttle body and plug hose ends. Remove oil filler cap. With a5-mm hex-wrench, remove the 10 bolts retaining the No. 3 timing belt cover and cylinder head rear cover.
5. Remove bolt holding the spark plug lead clamp from cylinder head. Disconnect 2 spark plug lead clamps from No. 3 cylinder head cover. Disconnect spark plug leads at the rubber boot. DO NOT pull on the leads. Remove 12 bolts and 4 nuts securing the cam covers, and remove the cam covers and gaskets.
6. Turn crankshaft pulley and align its groove with "0" timing mark on No. 1 timing belt cover. Ensure that timing marks of camshaft pulleys are aligned with timing marks of No. 4 timing belt cover. If not, rotate crankshaft one revolution (360 degrees) and align marks again.
7. Ensure cam bearing cap bolts are fully tightened to 14 ft. lbs. (20 N.m), in correct order. (Scheme 7)
8. Measure and record clearance of intake valves on cylinders No. 1 and 4, and exhaust valves on cylinders No. 1 and 5. (Scheme 8) Rotate crankshaft pulley 240 degrees (2/3 revolution). Measure and record clearance of intake valves on cylinders No. 3 and 5, and exhaust valves on cylinders No. 3 and 6. (Scheme 9) Rotate crankshaft pulley another 240 degrees (2/3 revolution). Measure and record clearance of intake valves on cylinders No. 2 and 6, and exhaust valves on cylinders No. 2 and 4. (Scheme 10)
9. Determine if clearance is within specification. See «VALVE CLEARANCE SPECIFICATIONS TABLE (SC300)»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments). If clearance adjustment is required, rotate crankshaft pulley to position lobe upward on valve to be adjusted.
10. Use Valve Clearance Adjuster (SST 09248-55011) to press valve lifter downward. Press valve lifter downward using SST (A), install SST (B) between camshaft and valve lifter and remove SST (A). Remove adjusting shim with a small screwdriver and magnet. (Scheme 4)
11. Using a micrometer, measure thickness of shim just removed. Select a new shim that will give correct valve clearance. See «VALVE CLEARANCE SPECIFICATIONS TABLE (SC300)»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments). Shims are available in thicknesses of.0984-.1299" (2.50-3.30 mm) in.002" (.05 mm) increments.
12. Install proper shim. Using SST (A), press downward on valve lifter and remove SST (B). Recheck valve clearance. Reinstall cylinder head covers using new gaskets. Tighten cylinder head cover bolts to 48 INCH lbs. (5.4 N.m). Install remaining components in reverse order of removal. Fill cooling system and check for leaks.

VALVE CLEARANCE SPECIFICATIONS

ES300

1. Ensure engine is at normal operating temperature. Connect timing light to No. 1 plug wire. Connect tachometer to IG- terminal of engine check connector. (Scheme 11)
2. Install jumper wire between terminals TE1 and E1 of engine check connector. (Scheme 12) Ensure idle speed is within specification. See «IDLE SPEED SPECIFICATIONS»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table under IDLE SPEED & MIXTURE. Ensure base timing is within specification. See «IGNITION TIMING»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table. Adjust timing by turning distributor.
3. Remove jumper wire from engine check connector and check that advance timing is within specification. See «IGNITION TIMING»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table.

IGNITION TIMING

Scheme 11

Scheme 12

LS400 & SC400

1. Connect timing light to No. 6 spark plug wire. Connect tachometer to IG- terminal of engine check connector. Bring engine to normal operating temperature. (Scheme 13)or (Scheme 15).
2. Install jumper wire between terminals TE1 and E1 of engine check connector. (Scheme 14)or (Scheme 16). Ensure idle speed is within specification. See «IDLE SPEED SPECIFICATIONS»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table under IDLE SPEED & MIXTURE. Ensure base timing is within specification. See «IGNITION TIMING»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table under ES300. Remove jumper wire from engine check connector.
3. If ignition timing is not within specifications, check the following: Ensure throttle valve is fully closed. Ensure there is continuity between terminals IDL and E2 of throttle position sensor. Check valve timing.

Scheme 13

Scheme 14

SC300

1. Ensure engine is at normal operating temperature. Connect timing light to engine. Connect tachometer to IG- terminal of engine check connector. (Scheme 15)
2. Install jumper wire between terminals TE1 and E1 of engine check connector. (Scheme 16) Ensure idle speed is within specification. See «IDLE SPEED SPECIFICATIONS»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table under IDLE SPEED & MIXTURE. Ensure base timing is within specification. See «IGNITION TIMING»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table under ES300. Adjust timing by turning distributor.
3. Remove jumper wire from engine check connector and check that advance timing is within specification. See «IGNITION TIMING»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table under ES300.

Scheme 15

Scheme 16

IDLE SPEED & MIXTURE

Note. Mixture adjustment IS NOT a part of normal tune-up procedure and should only be performed when mixture control unit is replaced or vehicle fails emissions testing.

IDLE SPEED

Note. Idle speed is controlled by the computer and idle speed control system.

1. Install tachometer to proper terminals. (Scheme 11), (Scheme 13) or (Scheme 15). Start engine and ensure idle speed is within specification. See «IDLE SPEED SPECIFICATIONS»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table.
2. If idle speed is not within specification, check ISC valve, wiring and ECU. See IDLE CONTROL SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.

IDLE SPEED SPECIFICATIONS

IDLE MIXTURE

Note. Idle mixture must be checked with air cleaner installed, all air intake system hoses and vacuum lines connected, EFI system wiring connectors tight, transmission/transaxle in Neutral, all accessories and cooling fan off (if equipped) and engine at normal operating temperature.

1. Ensure idle speed is within specification. Install jumper wire between proper terminals of check engine connector. Connect positive (+) probe of voltmeter to terminal VF or VF1 and negative (-) probe to terminal E1. (Scheme 12)
2. Start engine and maintain engine RPM at 2500 RPM for at least 90 seconds. With engine RPM at 2500, count the number of times volt-meter fluctuates between specified voltage. See «IDLE MIXTURE TEST SPECIFICATIONS»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table.
3. If the number of fluctuations is less than the minimum, check for air leaks at the air induction system, defective airflow meter or throttle body.
4. If fluctuations were within specification, accelerate and hold engine at 2500 RPM for approximately 2 minutes. Install exhaust gas analyzer probe in tailpipe at least 1.3 feet. Wait one minute and check idle mixture readings. If readings are not within specification, see «IDLE MIXTURE TROUBLE SHOOTING»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table.

Scheme 17

Scheme 18

1. Ensure idle speed is within specification. Install jumper wire between VF1 or VF2 and E1 terminals of check engine connector. Connect positive (+) probe of voltmeter to terminal VF1 for left bank or VF2 for right bank and negative (-) probe to terminal E1. (Scheme 17)and (Scheme 18).
2. Start engine and maintain engine RPM at 2500 RPM for approximately 120 seconds. With engine RPM at 2500, count the number of times voltmeter fluctuates between the specified voltage. See «IDLE MIXTURE TEST SPECIFICATIONS»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table.
3. If the number of fluctuations is less than minimum amount, check for air leaks at air induction system, defective airflow meter or throttle body.
4. If fluctuations were within specification, accelerate and hold engine at 2500 RPM for approximately 2 minutes. Install exhaust gas analyzer probe in tailpipe at least 1.3 feet. Wait one minute and check idle mixture readings. If readings are not within specification, see «IDLE MIXTURE TROUBLE SHOOTING»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table.

IDLE MIXTURE TEST SPECIFICATIONS

IDLE MIXTURE TROUBLE SHOOTING

THROTTLE POSITION SENSOR & SUB-THROTTLE POSITION SENSOR

1. Loosen TPS mounting screws. Unplug TPS and connect ohmmeter between throttle position sensor IDL and E2 terminals. (Scheme 19), (Scheme 20) or (Scheme 21). Insert feeler gauge between throttle stop screw and lever. Feeler gauge should be.020" (.50 mm) on ES300, or.0157" (.40 mm) on LS400 and SC400. On SC300, feeler gauge should be.018" (.45 mm) on TPS and.014" (.35 mm) on sub-TPS.
2. Rotate TPS clockwise until ohmmeter deflects. Tighten mounting screws. Using specified feeler gauge, recheck adjustment. See «THROTTLE POSITION SENSOR ADJUSTMENT»(/lexus/es/xv10-1991-1994/remont/adjustments/#engine-controls-adjustments) table. Remove ohmmeter and connect TPS.

THROTTLE POSITION SENSOR ADJUSTMENT

Scheme 19

Scheme 20

Scheme 21

DASHPOT CONTROL SYSTEM

For testing and adjustment procedures, see THROTTLE CONTROLS in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.

See also:
• VALVE CLEARANCE SPECIFICATIONS TABLE (ES300)