Kia Optima: RCV Control Solenoid Valve. Description and OperationWhen the throttle is closed, while the engine is running at cruise rpm (tip-out), the turbocharger boost pressure raises rapidly. The pressure wave strikes a compressor blades causing a knocking noise. To prevent this the ECM opens the recirculation valve which allows excessive boost pressure to vent back to the air cleaner side of the turbocharger compressor.

Adjustment
RCV Control Solenoid Valve. SpecificationsRemoval
1.
Disconnect the negative (-) battery
terminal.
2.
Remove the front wheel guard
clip(2EA).(Refer to the BD group - "Front bumper")
3.
D ...
Repair procedures
Inspection
Front Door Lock Actuator Inspection
1.
Remove the front door trim.
(Refer to the BD group - "Front door")
2.
Remove the front door module.
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Shift Lock System
For your safety, the Automatic Transaxle has a shift lock system which prevents
shifting the transaxle out of P (Park) unless the brake pedal is depressed.
To shift the transaxle out of P (Park):
...