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Mechanical Inspection: Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions.

WARNING: DO NOT use ignition switch during compression tests on fuel injected vehicles. Use a remote starter to crank engine. Fuel injectors on many models are triggered by ignition switch during cranking mode, which can create a fire hazard or contaminate the engine's oiling system.

Check engine compression with engine at normal operating temperature, all spark plugs removed and throttle wide open. See COMPRESSION SPECIFICATIONS  table.

COMPRESSION SPECIFICATIONS

Application (1) Specification
Compression Ratio
1.5L (VIN A) 9.0:1
1.8L (VIN C) 9.5:1
2.0L
(VIN F) 8.5:1
(VIN Y) 9.6:1
2.4L (VIN G) (2)
3.0L
(VIN H) 9.0:1
(VIN J) 10.0:1
(VIN K) 8.0:1
(VIN L) 9.0:1
3.5L (VIN P & R) 9.0:1
Compression Pressure
1.5L (VIN A) 192 psi (1324 kPa)
1.8L (VIN C) 199 psi (1372 kPa)
2.0L
(VIN F) 178 psi (1227 kPa)
(VIN Y) 170-225 psi (1172-1551 kPa)
2.4L (VIN G) 192 psi (1324 kPa)
3.0L
(VIN H) 171 psi (1179 kPa)
(VIN J) 185 psi (1276 kPa)
(VIN K) 156 psi (1076 kPa)
(VIN L) 119 (821 kPa)
3.5L (VIN P & R) 171 psi (1179 kPa)
Maximum Variation Between Cylinders (3) 14 psi (97 kPa)
(1) See MITSUBISHI INTRODUCTION article for VIN information.
(2) On Federal Eclipse, compression ratio is 9.5:1. For all other vehicles with VIN G engines, compression ratio is 9.0:1.
(3) On Eclipse 2.0L non-turbo engine, maximum variation between cylinders is 25 percent.