Toyota MR2 1988 Repair Manual page 57

EM-14
ENGINE MECHANICAL - Compression Check
EM1570
COMPRESSION CHECK
1.
2.
3.
4.
5.
NOTE: If there is lack of power, excessive oil consump-
tion or poor fuel economy after engine tune up, measure
the cylinder compression pressure.
WARM UP ENGINE
REMOVE SPARK PLUGS
Using a plug wrench (16 mml, remove the spark plugs.
DISCONNECT HIGH-TENSION CORD FROM IGNITION
COIL
DISCONNECT COLD START INJECTOR CONNECTOR
DISCONNECT INJECTOR CONNECTORS
6. MEASURE CYLINDER COMPRESSION PRESSURE
(a) Insert a compression gauge into the spark plug hole.
(b) Fully open the throttle.
(c) While cranking the engine, measure the compression
pressure.
NOTE: Always use a fully charged battery to insure that
at least 250 rpm can be attained.
(d) Repeat steps (a) through (c) for each cylinder.
Compression pressure:
4A-GE 12.6 kg/cm
2
(179 psi, 1,236 kPa)
4A-GZE 11.0 kg/cm 2 (156 psi, 1,079 kPa)
Minimum pressure:
4A-GE 10.0 kg/cmz (142 psi, 981 kPa)
4A-GZE 8.5 kg/cm
2
(121 psi, 834 kPa)
Difference between each cylinder:
1.0 kg/cm 2 (14 psi, 98 kPa) or less
(e) If compression of one or more cylinders is low, pour a
small amount of engine oil into that cylinder through
the spark plug hole and repeat steps (a) through (c)
for the cylinder with low compression.
• If adding oil helps the compression, chances are that
the piston rings and/or cylinder bore are worn or
damaged.
• If pressure remains low, a valve may be sticking or
seated improperly, or there may be leakage past the
gasket.