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Does anyone know at what ΔP across the DPF that the ECM triggers a passive Regen on 2015 LML ?

 

Currently running at around 72-73.

 

I remember driving with daughters boyfriend in his powerstroke. We had to keep driving because it was in the middle of a Regen when we got to our destination and he did not want to start it over.

 

I guess the Duramax is the only on of the three that measures this. Pretty cool considering the traducers it takes to get this. Although the Ford and Dodge guys would probably say (" less to worry about having to fix").

 

 

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What is currently running at around 72-73?

 

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DPF REGENERATION OPERATION

Regeneration may occur under several circumstances, called Active Regeneration, Passive Regeneration and Service Regeneration.

 

Active Regeneration

The regeneration operation is controlled by the ECM, which keeps track of the mileage driven, the amount of fuel consumed, the hours of operation and the exhaust differential pressure.

When the conditions are met for regeneration to occur, the ECM enters a different engine calibration strategy that includes additional fuel injection pulses (for 2011 and newer - 9th injector in the diesel exhaust. Prior to 2011 additional fuel was added to the injectors to raise exhaust temps). This heats the DFP inlet to above its normal operating temperature and regeneration begins.

For the process to complete satisfactorily, the vehicle must be operated continuously for approximately 18 minutes at speeds greater than 30 mph (50 km/h) to efficiently clean the filter. If the engine is allowed to return to idle during this time, the idle speed may be elevated slightly and the operating sound may be different. This is normal, and the driver doesn’t need to do anything different.

 

During regeneration, the exhaust temperature increases (greater than 500° C), which converts the particulates into harmless gases and ash. The DPF is then clean and ready to filter particulates again.

 

Driver Notification -- If normal driving does not provide the necessary conditions for regeneration to occur, the pressure differential continues to increase across the exhaust filter. The ECM will illuminate a CLEAN EXHAUST FILTER message on the instrument panel Driver Information Center (C/K only).

When this occurs drive the vehicle under the conditions necessary for a regeneration to take place until the CLEAN EXHAUST FILTER message no longer appears on the DIC.

Reduced Power -- However, if the CLEAN EXHAUST FILTER message is ignored, the ECM will eventually cause the engine to enter the Reduced Power mode, which will require the vehicle to be serviced.

 

Passive Regeneration

Passive regeneration occurs when exhaust gas temperature is elevated above 300°C

(575° F). These temperatures may be reached when the engine is under heavy load.

 

Service Regeneration

Service regeneration is performed with the Tech 2, and is used to clean a soot loaded filter during a dealership service visit.

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The DPF is currently running at pressure difference of 72 psi between inlet and outlet. The ECM must be set to some delta pressure that it will trigger the passive REGEN as well as mileage and fuel burned. I was wondering what that ECM delta trigger was. 90? 150?

 

That way one would know a REGEN is about to take place. Assuming you have CST2 or some other device to monitor it.

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From the few minutes I dug...GM uses the voltage of the sensors and grams measurement of soot. The voltage found on the pressure sensors converts in the ECM data to a pressure reading. I have yet to find a chart showing this but will look further.

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The DPF is currently running at pressure difference of 72 psi between inlet and outlet. The ECM must be set to some delta pressure that it will trigger the passive REGEN as well as mileage and fuel burned. I was wondering what that ECM delta trigger was. 90? 150?

 

That way one would know a REGEN is about to take place. Assuming you have CST2 or some other device to monitor it.

Active regen.

Passive regen can happen at any time or even continuously when under load enough to increase exhaust temps enough.

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Your on it 15HDriver. I bet in some tech service manual there is a chart that when certain volts/pressure is reached it triggers an active REGEN. Like Austingta stated, anytime your EGT is up it is naturally burning it clean.

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The DPF sensors are measuring the difference in pressure across the DPF., and the sensor is converting the pressures to electrical readings.

 

These readings and an estimate of the exhaust flow rate thru the dpf are used to estimate the amount of soot in the dpf.

 

Those running monitors capable of reading the data say that regen will start when the 'soot' level reaches 42g.

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  • 2 months later...

The pressure variance comes into play also like the OP was asking about. That is true whether a little VW diesel or a 15L Class 8 diesel. True, sensors are used also. Primarily EGT sensors that show increased EGT's above the norm that are a result of restriction levels down stream. Lots of variables taken into consideration.

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