Engine Controls - Adjustments: Other Lexus LS II

ENGINE MECHANICAL

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

VALVE CLEARANCE

Note. Check and adjust valves with engine cold.

1. Remove engine undercover. Drain coolant. Remove battery cover. Remove air cleaner inlet. Remove engine cover. Remove air cleaner cover and intake air assembly (air ducting). Disconnect control cables from throttle body.
2. Remove timing belt upper covers. Disconnect hoses and electrical connectors as necessary. Remove throttle body. Remove transmission oil dipstick. Remove spark plug wires and spark plugs. Remove cylinder head covers.
3. Rotate crankshaft clockwise until piston No. 1 is at TDC of compression stroke. Ensure groove on crankshaft pulley aligns with "0" timing mark on timing belt cover. Timing marks on camshaft pulleys should align with timing marks on timing belt rear plates.
4. Measure and record clearance of intake valves for cylinders No. 1, 2, 5, 7 and 8, and exhaust valves for cylinders No. 1, 4 and 8. Rotate crankshaft 360 degrees. Measure and record clearance of intake valves for cylinders No. 3, 4 and 6, and exhaust valves for cylinders No. 2, 3, 5, 6 and 7.
5. Compare measured clearance with specified clearance. See VALVE CLEARANCE SPECIFICATIONS table. If clearance is within specification, go to step 8). If clearance is not within specification, rotate crankshaft until camshaft lobe of valve to be adjusted is facing upward, away from shim. VALVE CLEARANCE SPECIFICATIONS Application In. (mm) Intake .006-.010 (.15-.25) Exhaust .010-.014 (.25-.36)
6. Using a screwdriver, rotate valve lifter until notch is at a 90-degree angle to camshaft (perpendicular), facing centerline of cylinder head. Using Valve Lifter Press (SST 09248-05011), press valve lifter downward. Install Valve Lifter Stopper (SST 09248-05021) between camshaft and valve lifter. Remove valve lifter press. Using compressed air and magnet, remove shim by blowing air into shim hole.
7. Select a shim of appropriate thickness. See SELECTING SHIMS at end of VALVE CLEARANCE. Place shim onto valve lifter with imprinted numbers facing down. Press downward on valve lifter using valve lifter press. Remove valve lifter stopper. Recheck valve clearance after shim is installed.
8. To complete installation, reverse removal procedure. Use NEW gaskets as necessary. Tighten nuts and bolts to specification. See TORQUE SPECIFICATIONS.

Scheme 3

Scheme 4

SELECTING SHIMS

Shims are available in thicknesses of .0984-.1299" (2.50-3.30 mm), in increments of .002" (.05 mm). Using a micrometer, measure thickness of used shim (shim that was removed). Use the following formulas to determine how thick the new shim should be

1. Intake Valve Subtract .008" (.20 mm) from the measured (actual) valve clearance. Add the result to the thickness of the used shim. The final result represents the thickness of the new shim.
2. Exhaust Valve Subtract .012" (.30 mm) from the measured (actual) valve clearance. Add the result to the thickness of the used shim. The final result represents the thickness of the new shim.

IGNITION TIMING

Note. Ignition timing is not adjustable.

1. Warm engine to normal operating temperature. Turn ignition off. Remove battery cover. Remove air cleaner and air intake duct. Remove engine cover. Connect timing light to spark plug wire for cylinder No. 6.
2. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Scan tool is used to read engine RPM. Apply parking brake. Ensure all accessories are off. Place transmission Neutral. Start engine and maintain engine speed at 2500 RPM for 90 seconds and then allow engine to idle. Ensure idle speed is 650-750 RPM.
3. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 of DLC No. 1. (Scheme 6) Connector is located near air intake chamber. Check base timing. See IGNITION TIMING table.
4. If base timing is correct, procedure is complete. If base timing is not correct, check for one or more of the following conditions. Repair as necessary. Throttle valve is being prevented from fully closing. Throttle position sensor is misadjusted (indicated by no continuity between terminals IDL1 and E2 of throttle position sensor connector). See THROTTLE POSITION (TP) SENSOR. Valve timing is incorrect (timing belt is not correctly installed).

IGNITION TIMING

Scheme 5

Scheme 6

IDLE SPEED

Note. Idle speed is controlled by the ECM and is not adjustable. Check and adjust idle speed with air cleaner installed, all air intake system hoses and vacuum lines connected, electronic fuel injection system wiring connectors tight, transmission/transaxle in Neutral, ignition timing properly set, A/C and all accessories off and engine at normal operating temperature.

1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Scan tool is used to read engine RPM. Apply parking brake. Place transaxle in Neutral. Start engine and maintain engine at 2500 RPM for 90 seconds and then allow engine to idle.
2. Ensure idle speed is 650-750 RPM. If idle speed is not 650-750 RPM, check Idle Air Control (IAC) valve, wiring and Electronic Control Module (ECM). See IDLE CONTROL SYSTEM in «SYSTEM/COMPONENT TESTS»(ref-22208) article. Remove scan tool.

IDLE MIXTURE

Note. Idle mixture is controlled by the ECM and is not adjustable. If vehicle fails emissions test, Heated Oxygen Sensor (HO2S) may be faulty, causing a trouble code to set. See G - TESTS W/O CODES article.

THROTTLE POSITION (TP) SENSOR

Note. Vehicles with Traction Control System (TRAC) are equipped with a main TP sensor and a sub-TP sensor. Use the following procedure to adjust main TP sensor. To adjust sub-TP sensor, see SUB-THROTTLE POSITION (SUB-TP) SENSOR.

SUB-THROTTLE POSITION (SUB-TP) SENSOR

Note. Vehicles with Traction Control System (TRAC) are equipped with a main TP sensor and a sub-TP sensor. Use the following procedure to adjust sub-TP sensor. To adjust main TP sensor, see THROTTLE POSITION (TP) SENSOR.

THROTTLE OPENER

Warm engine to normal operating temperature. Ensure idle speed is 650-750 RPM. Disconnect vacuum hose from throttle opener, and plug hose end. Run engine at 2500 RPM then release throttle. See THROTTLE OPENER SET SPEED SPECIFICATIONS table. If throttle opener set speed is not as specified

1. Turn throttle opener adjustment screw until engine speed is within specification. (Scheme 3)

THROTTLE OPENER SET SPEED SPECIFICATIONS

Scheme 7

PARK/NEUTRAL POSITION (PNP) SWITCH

Loosen bolt that secures PNP switch to transmission. Move shift shaft into Neutral (2 detents from Park). Align groove on shift shaft with neutral basic line on PNP switch. (Scheme 8) Tighten bolt.

Scheme 8