Valve timing adjustment
Valve timing determines when the valves open relative to piston position.
Symptoms
- Power drops, fuel use rises, the engine starts hard, and cam/crank correlation faults appear.
What's included
- A shift of even one tooth on a chain or belt is immediately noticeable: power drops, consumption rises, starting becomes difficult and camshaft-correlation faults appear. We check actual timing with a scanner in live data and compare it with specification; this is more accurate than visual timing marks, which do not show chain stretch. On variable-valve-timing engines we also check the actuators and control valves, since they are often the cause rather than the timing drive itself. Adjustment follows the manufacturer's procedure and is verified afterwards.
Additional checks
- Measured timing values checked against factory specification
- Verification of the result after adjustment
Why it matters
Checking actual timing with a scan tool is more accurate than a visual mark check, which won't reveal chain stretch. On engines with variable valve timing, the actuators and control valves are often the real cause, not the timing set itself.
More details
Valve timing determines the exact moment the valves open relative to piston position. A shift of even a single tooth on the chain or belt is felt right away: power drops, consumption rises, the engine starts hard, and crank-cam correlation fault codes appear. We check the actual timing with a scanner in the live data and compare it against spec — more accurate than a visual check of the timing marks, which doesn't reveal chain stretch. On engines with variable valve timing we additionally check the operation of the phasers and control valves: the cause is often there rather than in the timing chain or belt itself. Adjustment is carried out according to the manufacturer's procedure with the result verified.
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