2. Operate the vehicle while the engine is running at normal operating temperature.
3. Disconnect the ignition wires from the spark plug.
4. Disconnect the fuel injector electrical connector.
5. Remove all spark plugs.
Note: Do not introduce foreign objects into the throttle valve opening. Damage to the electronic throttle body may require replacement of the entire electronic throttle body assembly.
6. Lock the throttle linkage in its wide open position.
7. Install the engine cylinder compression tester on the cylinder to be tested.
8. Using the vehicle's starter, crank or crank the engine for 4 compression or exhaust strokes for the cylinder under test. If the engine cranks more than 4 compression strokes, test the cylinder again.
9. Record compression values.
10. Remove the compression tester from the engine cylinder to be tested.
11. Repeat steps 8-11 for each additional cylinder. To obtain reliable test results, all engine cylinders must be tested.
12. If either cylinder has a low compression ratio, inject approximately 15 ml of engine oil into the cylinder through the spark plug hole.
13. Repeat steps 8-11 for all low compression cylinders.
14. The minimum compression ratio in any cylinder must be at least 70 percent of the cylinder with the highest compression ratio. In no cylinder should the pressure be less than 690 kPa (100 psi). For example, if the highest pressure in any of the cylinders is 1035 kPa (150 psi), then the lowest allowable pressure for any other cylinder should be 725 kPa (105 psi). Multiply the value of the highest pressure in the cylinder by 70%: 1035 kPa x 70% = 725 kPa (150 psi x 70% = 105 psi). This must be done to determine the lowest allowable pressure in any other cylinder.
- Normal: Compression increases quickly and evenly up to a precisely defined compression ratio.
- Piston ring leakage: Compression is low on the first compression stroke. Compression increases on subsequent compression cycles, but does not reach the normal value. Compression is greatly improved after the addition of oil.
- Valve leakage: Compression is low on the first compression stroke. Compression does not increase on subsequent compression cycles and does not reach normal values. Compression does not improve significantly or does not increase at all after adding oil.
- Head gasket leak: Compression is low on the first compression stroke. Compression does not increase on subsequent compression cycles and does not reach normal values. Compression does not improve significantly or does not increase at all after adding oil. Neighboring cylinders have the same or similar low compression readings.
15. If the compression in one or more cylinders reaches the minimum predetermined compression value, repair or replace any damaged or worn components and test the engine again.