3588547 Volvo.Penta Tube

Illustration 1 g00664930
Typical display of the level of detonation on the Digital Diagnostic Tool (DDT)Three bars of detonation are shown.If detonation occurs, the control module will perform the following actions:
Continuously illuminate the "" lamp.
Activate a 326-01 diagnostic code.
Retard the ignition timing.If detonation occurs, the control module will retard the timing in order to stop detonation from occurring. The control module can retard the timing by as little as three degrees for light detonation. The control module can retard the timing by a maximum of six degrees for severe detonation.As the detonation level decreases, the control module will begin to advance the timing out of the detonation retarded timing. A proportional strategy is used to advance the timing. The rate of advance depends on the severity of the detonation. If the detonation level is low, the advance rate is faster. The fastest rate of timing advance out of detonation is two degrees per minute.If the ignition timing is fully retarded and severe detonation continues, the control module will perform these actions.
Continuously illuminate the "SHUTDOWN" lamp.
Activate a 325-00 diagnostic code.
Activate the "Shutdown Relay Output".Detonation can be caused by many different factors. Therefore, this procedure has many test steps. Usually, the root cause of detonation is identified early in the procedure.
Illustration 2 g01043894
Schematic diagram of the detonation sensorsTest Step 1. Check the TimingNote: The desired timing will vary for different engine applications.Use the Digital Diagnostic Tool (DDT) to check the engine timing. For the correct desired timing for the engine application, refer to the appropriate Engine Performance, "Fuel Usage Guide".Expected Result:The desired timing is correct.Results:
OK - The timing is correct for the engine application. Proceed to Test Step 3.
Not OK - Detonation occurs because the timing is not correct for the engine application.Repair: Use the DDT to set the proper timing. Verify that the original problem is resolved.STOPTest Step 2. Adjust the Timing
Operate the engine at full load or under the conditions that cause the detonation. Note the level of detonation.
Note the original ignition timing. Then retard the ignition timing by three to six degrees. Check for a change in the level of detonation.Expected Result:The level of detonation decreases.Results:
OK - Retarding the timing causes the level of detonation to decrease. Proceed to Test Step 3.
Not OK - Retarding the timing does not change the level of detonation. Proceed to Test Step 7.
Not OK - Retarding the timing causes the level of detonation to increase. Proceed to Test Step 8.Test Step 3. Check the Air/Fuel RatioNote: The air/fuel ratio will vary for different engine applications. The inlet manifold air temperature will affect the air/fuel ratio.
Verify that the engine is operating with the correct air/fuel ratio.Expected Result:The engine is operating with the correct air/fuel ratio.Results:
OK - The air/fuel ratio is correct. Proceed to Test Step 5.
Not OK - The detonation is caused by an incorrect air/fuel ratio.Repair: Correct the air/fuel ratio. Verify that the original problem is resolved.STOPTest Step 4. Richen the Air/Fuel Mixture
If the air/fuel mixture is too rich, detonation will occur. To help prevent damage to the engine, do not richen the air/fuel mixture by a large amount. Do not allow the engine to detonate excessively.
Adjust the ignition timing to the original setting.
Use the DDT in order to monitor the level of detonation. Slightly richen the air/fuel mixture.Expected Result:When the air/fuel mixture is slightly richened, the level of detonation increases.Results:
OK - Richening the air/fuel mixture increases the level of detonation. The cause is actual detonation. Proceed to Test Step 6.
Not OK - Richening the air/fuel mixture does not affect the level of detonation, or there is slightly less detonation.Repair: The cause of the detonation is undetermined. Reset the system and troubleshoot any active diagnostic codes.STOPTest Step 5. Check the Inlet Manifold Air TemperatureNote: The inlet manifold air temperature will affect the air/fuel ratio. The inlet manifold air temperature will vary for different ratings of water temperature regulators (aftercooler).
Verify that the engine is operating with the correct inlet manifold air temperature.Expected Result:The inlet manifold air temperature is acceptable for the engine.Results:
OK - Proceed to Test Step 11.
Not OK - The detonation is caused by an incorrect inlet manifold air temperature.Repair: Correct the inlet manifold air temperature. Verify that the original problem is resolved.STOPTest Step 6. Measure the Cylinder PressureNote: An accumulation of deposits can cause detonation. Applications that use landfill gas are more prone to deposits.Measure the cylinder pressure. For typical cylinder pressures, refer to the engine's Operation and Maintenance Manual.Expected Result:The cylinder pressure is within the normal range.Results:
OK - The cylinder pressure is acceptable. The detonation is not due to deposits. Proceed to Test Step 11.
Not OK - The cylinder pressure has risen by one or more compression ratios.Repair: The engine needs a top end overhaul in order to remove the deposits. For information, refer to Operation and Maintenance Manual, "Overhaul (Top End)".STOPTest Step 7. Check the Methane Number of the Fuel
Obtain a fuel analysis of the gas.
Enter the data from the fuel analysis into the Caterpillar Software Program, LEKQ6378, "Methane Number Program". The software calculates the fuel's methane number.
Compare the methane number to the recommendation from the appropriate Engine Performance, "Fuel Usage Guide".Expected Result:The methane number of the fuel is compatible with the engine.Results:
OK - The cause of detonation is undetermined. Reset the system and troubleshoot any active diagnostic codes.
Not OK - The methane number of the fuel is