Compression testing becomes useful when misfire or no-start evidence points toward mechanical sealing or timing after ignition and mixture checks.
Why this matters
A good answer separates immediate safety, evidence preservation, and the next useful test.
Evidence to capture first
- Relative compression during cranking
- Cylinder contribution and misfire pattern
- Oil use, coolant loss, valve-train noise, and cam/crank correlation
A disciplined path
- Use relative compression as a low-intrusion screen
- Disable fuel and ignition correctly
- Perform gauge or leak-down testing when indicated
- Compare cylinders and service limits
Decision point
Choose the action that preserves evidence and keeps the vehicle safe; avoid clearing, disconnecting, or replacing parts just to see what changes.
Source desk
Use current model-specific service information for specifications, connector locations, disabling procedures, and tightening values. The following public resources support the broader safety or system context used in this guide.
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