1990 Mazda 323 Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Engine Compression

  1. Ensure battery is fully charged and engine is at normal operating temperature. Allow engine to cool for 10 minutes. Remove spark plugs and disconnect ignition coil primary connector.
  2. Hold throttle valve fully open during test. Attach compression gauge and crank engine until maximum pressure is reached at each cylinder. See COMPRESSION SPECIFICATIONS  table. Lowest cylinder pressure should be at least 75 percent of highest cylinder pressure.
COMPRESSION PRESSURE SPECIFICATIONS (1)

Application Minimum psi (kg/cm2 ) @ RPM Standard psi (kg/cm2 ) @ RPM
Miata (1.6L) 135 (9.5) @ 300 192 (13.5) @ 300
Protege (1.8L)
SOHC 121 (8.5) @ 300 173 (12.2) @ 300
DOHC 128 (9.0) @ 300 182 (12.8) @ 300
323 (1.6L) 135 (9.5) @ 300 192 (13.5) @ 300
(1) Difference between cylinders should not exceed 28 psi (2.0 kg/cm2 ).
Factory Service Tools

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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.

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