Service manual

G420E/G424E Tier LP Engine Maintenance Schedule 34

Inspect for Intake Leaks

z Visually inspect the intake manifold, throttle

assembly (D), and manifold adapters (E), for

looseness and leaks. Repair as necessary.

(D) Throttle Assembly (E) Manifold Adapter

(F) TMAP Sensor

Inspect Throttle Assembly

z Visually inspect the throttle assembly motor

housing for coking, cracks and missing cover-

retaining clips. Repair and/or replace as

necessary.

NOTE

Refer to the LP mixer and throttle section

of the service manual for procedures on

removing the mixer and inspecting the

throttle plate.

Checking the TMAP Sensor

z Verify that the TMAP sensor (F) is mounted

tightly into the manifold adapter (E), with no

leakage.

z If the TMAP is found to be loose, remove the

TMAP retaining screw and the TMAP sensor

from the manifold adapter.

z Visually inspect the TMAP O-ring seal for

damage. Replace as necessary.

z Apply a thin coat of an approved silicon lubricant

to the TMAP o-ring seal.

z Re-install the TMAP sensor into the manifold

adapter and securely tighten the retaining screw.

Inspect Engine for Exhaust

Leaks

z Start the engine and allow it to reach operating

temperatures.

z Perform visual inspection of exhaust system.

z Repair any/all leaks found.

Replace Oxygen Sensor

1. Stop engine and wait until the exhaust pipe and

exhaust pipe is cooled.

2. Disconnect the electrical connector of oxygen

sensor.

3. Remove oxygen sensor.

4. Assemble new oxygen sensor.

Tightening torque : 45 N•m (32.5 lb•ft)

5. Connect the electrical connector of oxygen sensor.