Kia 2004.5 Spectra Service Technical Training page 68

2004.5 Spectra Technology
Looking at the intake valve timing on the non-CVVT
engine (top), at 12 o'clock (top), it starts to open 9
degrees before the piston reaches TDC and is closed
43 degrees after TDC.
The CVVT engine varies intake valve timing with the
opening occuring between 11 degrees ATDC and 29
degrees BTDC, a 40 degree range based on engine
load and RPM. It follows then, that the intakevalve
closes between 19 and 59 degrees after BDC.
CVVT ASSEMBLY
CVVT is a vane type assembly with an operational
range of 0 to 40 degrees crank angle (20 degrees
camshaft angle or CA). The assembly rotates with the
exhaust camshaft at engine speed up to 6000 RPM.
Inside the CVVT assembly, the rotor vane rotates
causing a phase difference in the housing and rotor
vane to advance or retard intake camshaft timing as
shown in the above illustration. The rotor vane is in a
fixed position on the housing by a pin stopper when
rotated to maximum retard timing. When the Oil
Control Valve (OCV) supplies oil to the advance
chamber side, the stopper pin is unlocked and the
housing will advance (rotate). This will advance the
intake camshaft.
The OCV can "Hold" and maintain the oil and the
housing will not rotate. When the OCV drains oil from
the CVVT assembly, the housing will rotate and retard
the intake timing. The CVVT lock pin will re-engage
with maximum retard timing.
Powertrain
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