For 1990-2009 cars only
- Ensure that the vehicle's batteries are in good condition, and fully charged.
- Operate the vehicle until the engine is at normal operating temperature.
- Check the engine cranking speed. The minimum cranking speed specification must be met in order to obtain valid test results. Refer to Engine Cranking Speed Test.
- Disconnect the positive ignition coil wire plug from the ignition coil.
- Disconnect the fuel injector electrical connector.
- Remove all of the spark-plugs.
- Block the throttle linkage wide-open.
- Install the engine cylinder compression gauge to the cylinder being tested.
- Using the vehicle's starter motor, rotate (crank) the engine for four compression strokes (puffs) for the cylinder being tested. If the engine rotates for more than four compression strokes, re-test the cylinder.
- Record the compression reading.
- Remove the engine cylinder compression gauge from the cylinder being tested.
- Repeat steps eight through eleven for each additional cylinder. All cylinders must be tested to obtain valid test results.
- Check the compression readings. Refer to Engine Mechanical Specifications .
- If any cylinders have low compression, inject approximately 15 ml (1 oz) of engine oil into the cylinder through the spark plug hole.
- Repeat steps eight through eleven for all low compression cylinders.
- Check the compression readings. Refer to Engine Mechanical Specifications .
- If one or more cylinders fails to meet the minimum specified compression, repair or replace all damaged or worn components and re-test the engine.
Notice: Do not insert objects into the throttle plate opening. Damage to the throttle body can result, requiring replacement of the throttle body assembly.
| • | Normal: The compression builds up quickly and evenly to the specified compression. |
| • | Leaking: The compression is low on the first compression stroke. The compression builds up with the following strokes, but does not reach the specified compression. |
| • | Piston Rings Leaking: Compression is low on the first compression stroke. The compression builds up on the following strokes, but does not reach normal. Compression improves considerably when you add oil. |
| • | Valves Leaking: Compression is low on the first compression stroke. The compression does not build up on the following strokes, and does not reach normal. Compression does not improve much, if at all, when you add oil. |
| • | Head Gasket Leaking: Compression is low on the first stroke. The compression does not build up on the following strokes, and does not reach normal. Compression does not improve much, if at all, when you add oil. Adjacent cylinders have the same, or similar, low compression readings. |
