Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: On-vehicle Inspection

ON-VEHICLE INSPECTION

CAUTION / NOTICE / HINT

CAUTION:

To prevent injury due to contact with an operating V-ribbed belt or cooling fan, keep your hands and clothing away from the V-ribbed belt and cooling fans when working in the engine compartment with the engine running or the engine switch on (IG).

PROCEDURE

1. INSPECT ENGINE COOLANT

Click here

2. INSPECT ENGINE OIL

Click here

3. CHECK BATTERY CONDITION

Click here

4. INSPECT SPARK PLUG

Click here

5. INSPECT AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY

(a) Remove the air cleaner filter element sub-assembly.

(b) Visually check that the air cleaner filter element sub-assembly is not damaged or excessively oily.

(c) Install the air cleaner filter element sub-assembly.

6. INSPECT V-RIBBED BELT

Click here

7. INSPECT V-RIBBED BELT TENSIONER ASSEMBLY

(a) Remove the V-ribbed belt.

Click here

(b) Turn the V-ribbed belt tensioner assembly clockwise and counterclockwise and check that it turns smoothly and does not catch.

HINT:

If the V-ribbed belt tensioner assembly does not turn smoothly or catches, replace the V-ribbed belt tensioner assembly.

(c) Install the V-ribbed belt.

Click here

8. INSPECT VALVE LASH ADJUSTER ASSEMBLY NOISE

(a) Rev up the engine several times. Check that the engine does not emit unusual noises.

(b) If unusual noises occur, warm up the engine and idle it for 30 minutes or more, then perform the inspection.

HINT:

If any defects or problems are found during the inspection, perform valve lash adjuster assembly inspection.

Click here

9. INSPECT IGNITION TIMING

(a) Warm up and stop the engine.

(b) Connect the Techstream to the DLC3.

(c) Start the engine and run it at idle.

(d) Turn the Techstream on.

(e) Enter the following menus: Powertrain / Engine / Data List / IGN Advance.

Powertrain > Engine > Data List

Tester Display
IGN Advance

Standard Ignition Timing:

12 to 24° BTDC at idle

(f) Check that the ignition timing advances immediately when the engine speed is increased.

(g) Enter the following menus: Powertrain / Engine / Active Test / Connect the TC and TE1 / ON.

Powertrain > Engine > Active Test

Active Test Display
Connect the TC and TE1

Data List Display
IGN Advance

(h) Monitor IGN Advance of the Data List.

Standard Ignition Timing:

8 to 12° BTDC at idle

10. INSPECT ENGINE IDLE SPEED

(a) Warm up and stop the engine.

(b) Connect the Techstream to the DLC3.

(c) Start the engine and run it at idle.

(d) Turn the Techstream on.

(e) Enter the following menus: Powertrain / Engine / Data List / Engine Speed.

Powertrain > Engine > Data List

Tester Display
Engine Speed

(f) Read the value displayed on the Techstream.

Standard Idle Speed:

650 to 750 rpm

11. INSPECT COMPRESSION

NOTICE:

Keep the intake manifold and spark plug holes free of foreign matter when measuring the compression pressure.

(a) Warm up and stop the engine.

(b) Check for DTCs.

Click here

(c) Remove the 6 spark plugs.

Click here

(d) Disconnect the fuel injector connectors.

(e) Check the cylinder compression pressure. (1) Insert a compression gauge into the spark plug hole. (2) While cranking the engine, measure the compression pressure. Standard Compression Pressure: 1400 kPa (14.3 kgf/cm2, 203 psi) Minimum Compression Pressure: 1050 kPa (10.7 kgf/cm2, 152 psi) Pressure Difference between Each Cylinder: 200 kPa (2.0 kgf/cm2, 29 psi) or less NOTICE: Always use a fully charged battery to obtain an engine speed of 250 rpm or more. Inspect all cylinders in the same way. Measure the compression pressure as quickly as possible. (3) If the cylinder compression is low, pour a small amount of engine oil into the cylinder through the spark plug hole then inspect the cylinder compression pressure again. HINT: If adding oil increases the compression pressure, the piston rings and/or cylinder bore may be worn or damaged. If the compression pressure stays low, a valve may be stuck or seated improperly, or there may be leaks in the cylinder head gasket.

(f) Connect the fuel injector connectors.

(g) Install the 6 spark plugs.

Click here

(h) Clear the DTCs.

Click here

NOTICE:

After performing the inspection, clear the DTCs and confirm that DTCs are not stored again or that the normal system code is output if using a check wire.

12. INSPECT CO/HC

HINT:

This check determines whether or not the idle CO/HC complies with regulations.

(a) Start the engine.

(b) Run the engine speed at 2500 rpm for approximately 180 seconds.

(c) Insert a CO/HC meter testing probe at least 40 cm (1.31 ft.) into the tailpipe during idle.

(d) Immediately check the CO/HC concentration at idle and then at an engine speed of 2500 rpm.

HINT:

When performing a 2 mode test (with the engine idling/running at 2500 rpm), the measurement procedures are determined by applicable local regulations.

If the CO/HC concentration does not comply with the regulations, perform troubleshooting in the order given below.

(1) Check for DTCs.

Click here

(2) See the following table for possible causes, then inspect the applicable parts and repair them if necessary.

CO	HC	Problem	Cause
Normal	High	Rough idle	Faulty ignition: Incorrect valve timing Fouled, shorted or improperly gapped spark plugs Incorrect valve clearance (valve lash adjuster assembly) Leaks in intake or exhaust valves Leaks in cylinders
Low	High	Rough idle (Fluctuating HC reading)	Vacuum leaks: PCV hoses Intake manifold Throttle with motor body assembly Brake booster line Lean mixture causing misfire
High	High	Rough idle (Black smoke from exhaust)	Restricted air cleaner filter element sub-assembly Plugged PCV valve Faulty SFI system: Fuel pressure regulator assembly Engine coolant temperature sensor Mass air flow meter sub-assembly ECM Fuel injector assemblies Throttle position sensor (built into throttle with motor body assembly)