P0021 “A” Camshaft Position-Timing Over-Advanced or System Performance (Bank 2)

COMPONENT LOCATION

GENERAL DESCRIPTION

The CVVT (Continuously Variable Valve Timing) system is installed to the chain sprocket of the intake camshaft. This system controls the intake camshaft to provide the optimal valve timing for every driving condition. The ECM controls the Oil Control Valve(OCV), based on the signals output from mass air flow, throttle position and engine coolant temperature. The CVVT controller regulates the intake camshaft angle using oil pressure through the OCV. As result, the relative position between the camshaft and the crankshaft becomes optimal, and the engine torque improves, fuel economy improves, exhaust emissions decrease under overall driving conditions.

DTC DESCRIPTION

ECM monitors timing misalignment while no active faults is present and fully warmed up engine oil at idle.

If the timing is misaligned ECM determines that a fault exists and a DTC is stored.

possible causes

1.	Engine oil

2.	VVT solenoid

3.	Camshaft/crankshaft sensor

4.	VVT / timing system

SYSTEM INSPECTION

■ Visual Inspection

1.	Check oil level is O.K.

2.	Check oil and OCV is contaminated.

3.	Check for oil leakage around OCV.

Has a problem been found ?

	▶ Repair or replace as necessary.
	▶ Go to “Component Inspection” procedure.

COMPONENT INSPECTION

■ Check OCV and Filter

Check resistance of OCV

(1)	IG “OFF” and disconnect OCV connector.

(2)

Measure resistance between power and signal terminals of OCV. (Component Side)

9.4 ~10.4 [20°C(68°F)]

(3)

Is the measured resistance within specification ?

	▶ Go to next step as below.
	▶ Substitute with a known – good OCV and check for proper operation. If the problem is corrected, replace OCV .

Check operation of OCV

(1)	Start the engine and let it idle.

(2)

With OCV connector still disconnected, connect 12V and a ground to 2 and 1 of the OCV(Component side).

Specification :

Test Condition	Disconnect OCV connector	Apply battery voltage
Normal Value	Normal engine speed	Rough idle or engine stall

(3)

Has a problem been found?

	▶ Go to next step as below.
	▶ Go to “Check CVVT(Continuously Variable Valve Timing) Assembly” procedure.

Check OCV and Filter

(1)

IG “OFF”.

(2)	Check OCV filter for sticking or contamination.

(3)	Remove the OCV and visually check the spool column of OCV for contamination.

(4)

Has a problem been found?

	▶ Clean or replace as necessary.
	▶ Go to next step as below.

(5)	Apply 12V and a ground to 2 and 1 terminals of the OCV(Component side).

(6)	Verify that a “clicking” sound is heard when applying the battery voltage.

(7)	Repeat this procedure 4 or 5 times to ensure intake OCV reliability.

(8)

Is OCV working properly?

	▶ Go to next step as below.
	▶ Check OCV for contamination, deterioration, or damage. Substitute with a known-good OCV and check for proper operation. If the problem is corrected, replace OCV.

Check CVVT(Continuously Variable Valve Timing) Assembly

(1)	Remove the CVVT assembly.

(2)	Check that the CVVT assembly is locked.

(3)	The one of the 2 holes on the cam journal is for advances(upper) and the rest is for retards(lower). Apply masking tape to all oil path holes except the one advance hole(“B”) indicated by the arrow as shown in the figure.

(4)	To release the CVVT lock pin, wrap some tape around the tip of an air pressure adapter and apply low air pressure of approx. 150kPa(1.5kg/cm², 21 psi) to the exposed camshaft port. Wrap a shop towel or rag around the CVVT because residual oil may leak out of the unit when applying air pressure.

(5)

With low air pressure applied, turn the CVVT to the ADVANCE direction as indicated in the figure.

If too much air leaks when applying the low air pressure, the CVVT lock pin may not release and the CVVT may not turn.

(6)	Allow the CVVT assembly to move in the ADVANCE and DELAY directions to ensure there is no binding and that it moves freely.(Movable smoothly in the range about 20°)

(7)	Turn the CVVT by hand and make sure it locks in the maximum delay angle position.

(8)

Is CVVT assembly working properly?

	.
	▶ Replace the CVVT assembly

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