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

Non-Turbo

114 (8.0) @ 265

162 (11.4) @ 265

Turbo

98 (6.9) @ 265

139 (9.8) @ 265

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

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.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Mechanical Inspection: Compression

Use the Manual With the Right Hardware

When to See a Mechanic

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