Mechanical Inspection: Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. Ensure oil level and condition are okay. Ensure battery is fully charged. 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, which can create a fire hazard or contaminate the engine's oiling system.

COMPRESSION SPECIFICATIONS

Application

Minimum psi (kPa) @ RPM

Standard psi (kPa) @ RPM

B2300, B3000 & B4000

⁽¹⁾

Mazda6

2.3L ⁽²⁾

139 (958) @ 285

199 (1372) @ 285

3.0L

⁽¹⁾

Miata ⁽²⁾

146 (1007) @ 300

198 (1365) @ 300

MPV

⁽¹⁾

Protege & Protege5 ⁽²⁾

119 (821) @ 300

171 (1179) @ 300

Tribute

2.0L

⁽¹⁾

3.0L

⁽¹⁾

⁽¹⁾	Lowest compression reading should not be less than 75 percent of highest compression reading.

⁽²⁾	Difference between cylinders should not be more than 28 psi (193 kPa).