Cam and Crank
Cam and crank correlation testing — verify timing relationships, identify jumped timing, worn chains, and stretched belts. The cam/crank pattern tells you if the valvetrain is doing what it should.
Remember, cam/crank architecture can be very different. The VVT, sensors can be in the back, or the CKP can be as well. The reluctor can slip. Jumped chain — common.
Due diligence on design is the key.
Reference Waveforms
Known good cam and crank captures. Click any image to enlarge.
✓ Known Good — Cam/Crank with In-Cylinder
Field Notes: A CKP and CMP can be compared to a known good, alongside the In-Cylinder compression event. On this capture, the Right IC (In-Cylinder) is right on the money — timing relationship between cam, crank, and compression event looks exactly as expected.
🔍 Voltage Offset — CKP / CMP
Field Notes: When you have a voltage offset between CKP and CMP, it is always a physical layer issue — resistance, corrosion, or water intrusion. The scope is showing you a real-world impedance problem, not a sensor logic fault.
❌ Known Bad — All 4 Channels (CKP, CMP, In-Cylinder, Spark)
Field Notes: On this capture you can see the IC and the CMP are off — likely timing jumping. If this is a V6 or V8, consider more testing before committing to a diagnosis; one actuator could be faulty rather than a full timing chain failure.
Waveform Gallery
Waveform images and analysis for cam and crank will be added here.
📚 Gallery coming soon
Have a waveform to contribute? Send it in
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