Chevrolet Sonic Repair Manual: Crankcase Ventilation System Inspection/Diagnosis
- Results of Incorrect Operation
-
A plugged positive crankcase ventilation (PCV) orifice or hose may cause the following conditions:
- Rough idle
- Stalling or slow idle speed
- Oil leaks
- Oil in the throttle body
- Sludge in the engine
- Functional Check
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With these systems, any blow-by in excess of the system capacity, from a badly worn engine, sustained heavy load, etc., is exhausted into the throttle body and is drawn into the engine.
Proper operation of the crankcase ventilation system depends upon a sealed engine. If oil slugging or dilution is noted and the crankcase ventilation system is functioning properly, check the engine for a possible cause. Correct any problems.
If an engine is idling rough, inspect for a clogged PCV orifice, a dirty vent filter, air cleaner element, or plugged hose. Replace as required. Use the following procedure:
- Remove the PCV hose from the cylinder head cover.
- Operate the engine at idle.
- Place your thumb over the end of the hose in order to check for a vacuum. If there is no vacuum at the hose, inspect for the following items:
- Plugged hoses
- The manifold port
- Turn OFF the engine.
- Inspect the PCV orifice in the cylinder head cover for debris or blockage.
PCV
...
Positive Crankcase Ventilation Hose/Pipe/Tube Replacement
Removal Procedure
Remove the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct
Replacement.
Open the 2 positive crankcase ventilation pipe retainer clips ...
Other materials:
Forward Collision Alert (FCA) System
For vehicles with FCA, this system is intended to help avoid or reduce the harm
caused by front-end crashes. FCA provides a flashing visual alert and beeps when
approaching a vehicle directly ahead too quickly. FCA also provides a visual alert
if following another vehicle much too closely. The ...
Brake Pressure Modulator Valve Replacement
Removal Procedure
Warning: Refer to Brake Fluid Irritant Warning.
Caution: Refer to Brake Fluid Effects on Paint and Electrical
Components Caution.
Caution: Always connect or disconnect the wiring harness connector
from the EBCM/EBTCM with the ignition switch ...
Body Control System Description and Operation
The body control system consists of the body control module (BCM), communications,
and various input and outputs. Some inputs, outputs and messages require other modules
to interact with the BCM. The BCM also has discrete input and output terminals to
control the vehicle's body functions. ...
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