Section 228 (Engine Mechanical): Compression: Inspection

WARNING: This page is about a different car, the 2004 Toyota MR2, 2003 Toyota MR2, and 2002 Toyota MR2. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: If there is lack of power, excessive oil consumption or poor fuel economy, measure the compression pressure.

WARM UP AND STOP ENGINE
Allow the engine to warm up to normal operating temperature.
REMOVE IGNITION COILS (See REMOVAL & INSTALLATION (MR2) ).
REMOVE SPARK PLUGS
INSPECT CYLINDER COMPRESSION PRESSURE
1. Insert a compression gauge into the spark plug hole.
  
  Fig 1: Using Compression Gauge
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Fully open the throttle.
3. While cranking the engine, measure the compression pressure.
  NOTE: Always use a fully charged battery to obtain engine speed of 250 RPM or more.
4. Repeat steps a- c for each cylinder.
  NOTE: This measurement must be done in as short a time as possible.
  1. Compression pressure:
    1. 1,270 kPa (13.0 kgf/cm ² ,184 psi)
  2. Minimum pressure:
    1. 1,000 kPa (10.2 kgf/cm ² ,145 psi)
  3. Difference between each cylinder:
    1. 100 kPa (1.0 kgf/cm ² ,15 psi) or less
5. If the cylinder compression in one more cylinders is low, pour a small amount of engine oil into the cylinder through the spark plug hole and repeat steps a- c for cylinders with low compression.
  - If adding oil helps the compression, it is likely that the piston rings and/or cylinder bore are worn or damaged.
  - If pressure stays low, a valve may be sticking or seating is improper, or there may be leakage through the gasket.
REINSTALL SPARK PLUGS
REINSTALL IGNITION COILS (See REMOVAL & INSTALLATION (MR2) ).