PAN GP-OIL 2P9647 - Caterpillar

are cycling on and off during the test. Turn off the air conditioner. Make sure that other accessories such as cooling fans, air compressors, and power steering pumps are always on or always off and do not cycle during the test.
The test does not measure the power that is produced by the cylinders. The test only measures the percent of variance between cylinders in the same cylinder group.
The test indicates "Not OK" when the cylinder performance is weak. The weak cylinder is compared to the other cylinders that are in the same cylinder group. The test will indicate "Not OK" for a cylinder that is approximately 10 percent to 15 percent low on power.
Many customers may not notice a performance problem when only one cylinder is 10 percent to 15 percent low on power. This is especially true on engines with a large number of cylinders. Some applications are more sensitive to small drops in power.
Replacing a marginal fuel injector that tests "Not OK" may not always be in the customer's best interest. An example might be on an engine that has no performance complaint and the engine is near a scheduled maintenance interval. Use common sense.
The test does not currently detect high-power cylinders. A "Not OK" indication is given only for low-power cylinders.
ET will only compare the cylinders that are in the same cylinder group in order to determine whether a cylinder is "OK" or "Not OK". Cylinders in one cylinder group cannot be compared to cylinders in a different cylinder group. This is especially true on the 16 cylinder test. The three cylinder groups do not contain the same number of cylinders. This results in a difference in the numbers of the injection duration for the first group when the numbers are compared to the other two groups. This situation does not affect the test results.
The test checks for cylinder-to-cylinder variation, but the test does not measure the actual power. It is possible that an engine could have an entire set of fuel injectors that are uniformly low on power and test "OK". Although this is possible, it is unlikely. Typically in a worn set of fuel injectors or a damaged set of fuel injectors, some fuel injectors will have more degradation than other fuel injectors. This will cause an increase in the variance. The test should be able to find the variance.
An extremely weak cylinder may obscure a weak cylinder that is in the same cylinder group. If this happens, the test will find the extremely weak cylinder first. Then when that cylinder is repaired and the test is rerun, the repaired cylinder will test "OK", but a different cylinder in the same group may then test "Not OK". If another cylinder tests "Not OK" after a repair, verify that the cylinder is in the cylinder group that was repaired.