Engine Compression

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 1999 Mazda Protege, 1999 Mazda Millenia, 1999 Mazda MX-5 Miata, 1999 Mazda B4000, and 1999 Mazda B3000. However, it is still accessible from the selected car via links, so may be relevant.

Warm engine to normal operating temperature. Remove all spark plugs. Disconnect ignition coil primary wire connector. Hold throttle plate fully open. Crank engine and note compression pressure.

COMPRESSION SPECIFICATIONS

Application

Minimum psi (kg/cm² ) @ RPM

Standard psi (kg/cm² ) @ RPM

B2500

⁽¹⁾

B3000 & B4000

⁽¹⁾

Miata

146 (10.3) @ 300

209 (14.7) @ 300

Millenia ⁽²⁾

2.3L

121 (8.5) @ 250

164 (11.5) @ 250

2.5L

132 (9.3) @ 300

189 (13.3) @ 300

Protege ⁽²⁾

1.6L

146 (10.3) @ 300

195 (13.7) @ 300

1.8L

156 (11.0) @ 300

199 (14.0) @ 300

626 ⁽²⁾

2.0L

119 (8.4) @ 300

171 (12.0) @ 300

2.5L

141 (9.9) @ 250

203 (14.3) @ 250

⁽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 (2.0 kg/cm² ).

COMPRESSION RATIO

Application		Specification
B2500		9.4:1
B3000		9.14:1
B4000		9.0:1
Miata		9.5:1
Millenia
2.3L		10.0:1
2.5L		9.2:1
Protege
1.6L		9.0:1
1.8L		9.0:1
626
2.0L		9.0:1
2.5L		9.5:1