Mechanical Inspection: Compression
- When checking compression, disconnect connector for crankshaft position sensor, as this prevents ignition and fuel injection systems from operating. Connector for crankshaft position sensor is a 3-pin Black connector located near top of timing belt cover and contains Red, Black and Blue/White wires in the connector.
- Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions.
- After performing compression test, Diagnostic Trouble Code (DTC) for crankshaft position sensor must be cleared from Engine Control Module (ECM). DTC may be cleared from ECM by disconnecting negative battery cable for at least 10 seconds or using a scan tool. For clearing of DTC using scan tool, see CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM in TESTS W/CODES - TURBO article.
CAUTION:
When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.
COMPRESSION SPECIFICATIONS
| Application | psi (kg/cm2 ) |
|---|---|
| Normal Compression Pressure | 178 (12.5) |
| Minimum Compression Pressure | 133 (9.4) |
| Maximum Variation Between Cylinders | 14 (.9) |