Engine Compression
NOTE:
Always refer to Emission Control Label in engine compartment before starting tune-up. If manual and label differ, always use emission label specifications.
Check engine compression with engine at normal operating temperature, all spark plugs removed and throttle valves wide open at specified cranking speed. Ensure battery is fully charged.
ENGINE COMPRESSION TEST
| Model | Standard psi (kg/cm2 ) | Minimum psi (kg/cm2 ) | RPM | |||
|---|---|---|---|---|---|---|
| Cherokee, Comanche, Wagoneer & Wrangler | ||||||
| 2.5L, 4.0L & 4.2L | (1) | (1) | (1) | |||
| Grand Wagoneer | ||||||
| 5.9L V8 | 140 (9.8) | 120 (8.4) | 300 | |||
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