- Ensure that area around SCR system is clear of flammable materials.
- Inspect access panels.
- Inspect injector.
- Inspect bulkhead fittings.
- Ensure that urea and air lines are connected.
- Inspect sensors.
- Inspect wiring harness.
- Ensure that filter screens are in place.
- Ensure that drains are closed.
- Ensure that all lines are connected.
- Check for leaking fluids. Ensure all fluids that have leaked are cleaned up and properly disposed of.
- Check the A/C power supply.
- Check D/C power supply.
Partial Load Operation and Hydrocarbon Release Procedures
Extended operation at low load may cause increased oil consumption and allow unburned fuel to pass through the exhaust system. Unburned fuel and oil passing through the SCR system can result in aftertreatment system damage if allowed to accumulate. The accumulation of fuel and oil on the catalyst is referred to as Hydrocarbon (HC) Loading. To maintain engine efficiency, performance, and avoid possible SCR aftertreatment damage, the engine should be shut down rather than allowed to idle for an extended length of time.
The SCR control will continuously estimate HC catalyst levels and a warning will be triggered if the HC loading reaches a preset threshold.
If a warning occurs, a manually initiated mitigation procedure as prescribed below is required to prevent catalyst damage. This procedure slowly increases exhaust temperature and then catalyst temperature releases the HC from the catalyst. During this procedure, the aftertreatment system control will continue to estimate the HC catalyst loading.
If the aftertreatment control reports excessive HC loading, execution of the mitigation procedure is recommended as soon as possible. Do not allow exhaust temperatures to exceed outlined in the procedure. Failure to follow these recommendations may result in damage to the Aftertreatment system.
| Application | Maximum
Idle Duration |
Engine
Load |
|---|---|---|
| Hrs | <% | |
| C32, 3500, C175 | 10 | 10 |
It is recommended that if HC release procedure does need to be executed, it is more efficient to perform the procedure prior to shutting down and allowing the system to cool. Starting from a cold system is less effective and will burn more fuel.
The following fault codes are related to the hydrocarbon accumulation and release process:
SPN 2434-1 Engine Exhaust Manifold #1 Temperature #1: Low-Most Severe (3)
When SPN 2434-1 is active, this code requires the operator to follow the HC Release Procedure.
Level 3 - The Level 3 Code indicates that the operator must follow an HC Release Procedure to remove the high HC accumulated on the catalyst and protect the catalyst from damage. If an emergency occurs and the release procedure cannot be followed before exceeding the CEM inlet temperatures outlined in the procedure, the catalyst may be damaged.
SPN 2434-18 Engine Exhaust Manifold #1 Temperature #1: Low-Moderate Severity (2)
If SPN 2434-18 is active, continued idling or low load operation (typically 20% load or less) may result in catalyst HC loading levels requiring operator action to perform the recommended hydrocarbon release procedure.
Level 2 - The Level 2 Code is annunciated to provide the operator or technician a warning to change operation to prevent high HC accumulation. Engine HC Release Procedure must be ran to avoid a Level 3 diagnostic.
If your Cat Engine and Aftertreatment System are in an SPN 2434 Level 2 or Level 3 condition, the operator or engineer will need to find an opportunity to increase engine load to target a higher exhaust temperature. For variable speed propulsion applications, targeting a higher exhaust temperature can be accomplished by temporarily increasing engine speed thus load on the engine. The HC Release Procedure below will allow the engine to increase the engine exhaust temperature and remove the accumulated HC from the catalyst system.
To perform the HC Release Procedure to remove HC from the catalyst effectively and efficiently, follow the guidelines listed in the tables below:
| HC Release Procedure | |
|---|---|
| EH6, EH7, EH8, EH9 | |
| SCR Inlet Temperature | Time (Min) |
| |
15 |
| |
10 |
| |
15 |
For the operator to perform the procedure, engine speed, engine load (%), or power (kW) and SCR inlet temperature are to be displayed. Configure your monitoring system accordingly.
Perform the following procedure:
- Before increasing speed or load, ensure that all requested parameters are visible.
- Ensure that the engine load can be safely increased to increase exhaust temperature for the durations required. For example, the procedure could take 40 minutes or longer of load-controlled operation.
- Review the HC release procedure listed in this section.
When ready, raise the engine speed or load to increase the exhaust temperature. Be sure to monitor the SCR inlet temperature.
Maintain the prescribed temperature for the duration listed, then move on the next step. Holding longer than prescribed at a given temperature is acceptable.
Note: Targeted SCR Inlet Temperature tolerance: Adjust the engine speed or load to keep the SCR Inlet Temperature no more than
15° C (59° F) greater than the SCR Inlet Temperature target in the HC Release Procedure. If the SCR Inlet Temperature exceeds the threshold, then reduce the engine speed or load accordingly. - Maintain the SCR Inlet temperature until the HC release procedure is complete allowing the engine to return back to work. SPN 2434-1 Engine Exhaust Manifold #1 Temperature #1: Low-Most Severe (3) should be inactive and logged. SPN 2434-18 Engine Exhaust Manifold #1 Temperature #1: Low-Moderate Severity (2) should be inactive and logged
- If the codes are not cleared, then continue the last operating step at the targeted SCR inlet temperature. If higher engine loads, up to 40% are achievable
- Upon clearing the code, return the engine system to normal operation.