Mechanical Inspection: Compression

1999 Mazda Protege ES, AutomaticSECTION 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 (kg/cm2 ) @ RPM Standard psi (kg/cm2 ) @ RPM
Miata 146 (10.3) @ 300 209 (14.7) @ 300
Millenia (1)
2.3L 121 (8.5) @ 250 164 (11.5) @ 250
2.5L 132 (9.3) @ 300 189 (13.3) @ 300
Protege (1)
1.6L 146 (10.3) @ 300 195 (13.7) @ 300
1.8L 156 (11.0) @ 300 199 (14.0) @ 300
626 (1)
2.0L 119 (8.4) @ 300 171 (12.0) @ 300
2.5L 141 (9.9) @ 250 203 (14.3) @ 250
(1) Difference between cylinders should not be more than 28 psi (2.0 kg/cm2 ).
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

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

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.