Usage:
CONFIDENTIAL TIBU4565-01
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TECHNICAL INFORMATION BULLETIN |
JUNE 15, 2005 |
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ON-HIGHWAY ENGINE |
C9 (MTB1-UP) |
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Component Code 1091 |
SUBJECT: IDLE REDUCTION ON MASS TRANSIT BUS ENGINES
PROBLEM:
Mass transit bus C9 engines are equipped with Diesel Particulate Filters in place of standard mufflers. These devices physically trap particulate matter, or soot, and reduce engine out particulate emissions to near zero levels. Without elimination of the particulate matter, the filters will become plugged, resulting in excessive engine backpressure. To avoid this condition, the filters are designed to utilize normal operating temperature of the exhaust to oxidize the captured solid particles. This is referred to as passive regeneration.
Note: If large quantities of soot are allowed to accumulate in the filter without performing the required maintenance, the filter can be permanently damaged. Under these severe conditions, rapid oxidation of the accumulated soot may result in excessive exhaust temperatures. This can result in cracking or melting of the filter substrate.
If exhaust temperatures are insufficient for passive regeneration of the filter, excessive amounts of particulate matter collect in the filter resulting in high backpressure. The exhaust pressure monitor continuously measures the exhaust backpressure. Refer to System Operation, RENR7558, "Exhaust Pressure Monitor" for measuring continuous backpressure. If exhaust pressure exceeds specified levels, the warning lights will turn on in the engine compartment. Once the warning lights have turned on, the Diesel Particulate Filter must be serviced. Refer to Operation and Maintenance Manual, SEBU7729, "Exhaust Particulate Filter - Clean" for proper cleaning.
SOLUTION:
Excessive quantities of soot in the filter are primarily caused by extended continuous idle time.
Utilize the idle shutdown timer to limit the idle time to 20 minutes. Refer to Troubleshooting, RENR7561, "Idle Shutdown Time" for using the idle shutdown timer.
Set the following customer specified parameters:
- Idle shutdown time: 20 min.
- Allow idle shutdown override: Yes
The engine will shutdown after idling for 20 minutes if the following conditions are met:
- No vehicle speed is detected by the Engine Control Module (ECM)
- The transmission is in Neutral (depending on the transmission settings in the ECM)
- The service brake pedal is not depressed (depending on the transmission settings in the ECM)
- The engine is not under load
- The engine is at operating temperature and not in cold mode
The "Check Engine/Diagnostic" lamp will flash rapidly for 90 seconds prior to shutdown. If the clutch or brake is depressed during the 90 seconds, idle shutdown is overridden.
The engine may be restarted after idle shutdown.
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