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.

COMPRESSION SPECIFICATIONS

Application

Minimum psi (kg/cm2) @ RPM

Standard psi (kg/cm2) @ RPM

B2200

121 (8.5) @ 300

173 (12.2) @ 300

B2600i

142 (10.0) @ 280

185 (13.0) @ 280

Miata & 323 ⁽¹⁾

135 (9.5) @ 300

192 (13.5) @ 300

MPV

2.6L

142 (10.0) @ 280

185 (13.0) @ 280

3.0L

121 (8.5) @ 300

164 (11.5) @ 300

MX-3

1.6L

142 (10.0) @ 300

185 (13.0) @ 300

1.8L

142 (10.0) @ 300

192 (13.5) @ 300

MX-6 & 626

2.0L

119 (8.4) @ 300

171 (12.0) @ 300

2.5L

142 (10.0) @ 250

203 (14.3) @ 250

Navajo

⁽²⁾ 100 (7.0)

Protege

SOHC ⁽¹⁾

121 (8.5) @ 300

173 (12.2) @ 300

DOHC ⁽¹⁾

128 (9.0) @ 300

182 (12.8) @ 300

RX7

79 (5.5) @ 250

100 (7.0) @ 250

929

157 (11.0) @ 270

213 (15.0) @ 270

⁽¹⁾	Difference between cylinders should not be more than 28 psi (2.0 kg/cm2).

⁽²⁾	Lowest compression reading should not be less than 75 percent of highest compression reading.