Kia 2004.5 Spectra Service Technical Training page 77

2004.5 Spectra Technology
OCV WAVEFORM
Powertrain
Looking at the waveform on the left, the CKP and CMP
waveforms on the HSP can inspect the CVVT
operation. Let's review basic engine operation. The
waveform of 2-on/off square waves represents the
CMP while the waveform of multiple and close
together on/off signals represent the CKP. The CMP
has 1 signal at TDC per engine revolution while the
CKP has 58 + 2 (TDC reference) for 60 signals and
turns over twice per engine revolution.
Now lets look closely at a small part of the signal
(within the drawn box and moved to the waveform on
the right) to discuss the OCV operation. The engine is
running at idle condition. On the left side, note the
end of the CMP square wave. Moving to the right,
there are 4 CKP square waves. The 4 CKP waves
mark the 11° of intake cam opening timing at idle with
the OCV valve off. The state of cam timing is
maximum retarded.
The waveform on the left shows the engine RPM has
increased to 1200 RPM. Due to the increased RPM,
square waves have become closer together or
narrower but still the same height. Also the addition
of 2 square waves which represents a 12° advance
due to the OCV duty cycling ON. The intake camshaft
opening timing is now (11° fix + 12° OCV) 23°.
23