Mitsubishi 3000GT Service Manual page 80

ENGINE
COMPRESSION PRESSURE CHECK
(1) Prior to inspection, check to ensure that the engine oil,
starter motor and battery are in proper condition. Place
the vehicle in the following conditions.
l Engine coolant temperature: 80-95°C (176-203°F)
Lights, electric cooling fan and accessories: OFF
l
Transaxle: Neutral (P for A/T)
l
(2) Remove the spark plug cables.
(3) Remove all of the spark plugs.
(4) Disconnect the crankshaft position sensor connector.
NOTE
By so doing the engine control module stops performing
ignition and fuel injection.
(5) Cover the spark plug mounting holes with a shop towel,
crank the engine, and then check for foreign substances
deposited on the shop towel.
Caution
1. When you crank the engine, keep away from the spark
plug mounting holes.
2. If a compression measurement is performed with wa-
ter, oil, fuel, etc. in the cylinder due to the cracks
in the cylinders, these substances heated to a very
high temperature will blow off the spark plug mounting
holes and could be dangerous.
(6) ~I;II a compression gauge in a spark plug mounting
(7) Set the throttle valve in a fully opened position, and crank
the engine to measure the compression pressure.
Standard value:
Limit:
(8) Measure the compression pressure in each of the cylin-
ders and check that the difference in compression pres-
sure between the individual cylinders is less than the
limit value.
Limit: max. 98 kPa (14 psi)
1,270 kPa (185 psi) [250-400 rpm]
1,080 kPa (156 psi) [250-400 rpm]
min. 959 kPa (139 psi) [250-400 rpm]
min. 792 kPa (115 psi) [250-400 rpm]