Not sure about the DuraMax, but a friend of mine has a Furd. His truck started smoking badly and lost power on his way home from work. He had enough power to make it to the dealer whose first question was " Do you let it idle alot?". When his answer was "It's a diesel, I let it run to warm up and keep it running when I can" the mechanic immediately checked the EGR. He stated that excessive idling will cause carbon buildup on the EGR, which will cause it to stick. The mechanic recommended "gettin' on it" once in a while to burn/blow away the carbon. After a thourough cleaning of the EGR, his truck was up and running normal (relative to Furd).
LLY's EGR is more ap to be open at an idle and closed during cruising speeds, oppisite on a gasser engine. As far as getting on it to clean it out, my guess would be it would produce more soot.
From the scan tool data I have seen EGR operation is most always open at idle when ect tecmp is met. I dont feel one driver could get longer life than another due to driving habits.
The exhaust gas recirculation (EGR) valve is controlled by the engine control module (ECM) through the EGR motor high control and EGR motor low control circuits. The ECM supplies voltage that is near ignition voltage to the high and low control circuits at all times. This voltage is used by the ECM as a reference voltage during non EGR operation in order to detect circuit failures. The ECM will pulse width modulate (PWM) the low control circuit to ground and an increase in amperage on the high control circuit can be observed with a DMM when the EGR valve is commanded open. A lower pulse width will increase the open position of the valve. In order to close the EGR valve, the ECM will PWM the high control circuit to ground.
When the ignition is turned ON, the ECM will drive the EGR motor worm gear out with just enough force to touch the EGR valve stem. The ECM will do this 3 times in quick succession. This action determines the minimum closed position of the valve and only happens once per ignition cycle. If the valve is prevented from closing all of the way after the minimum closed position is learned, the scan tool EGR Position parameter will not reflect this position until the next ignition cycle. The EGR motor worm gear is not connected to the EGR valve stem and can only push the valve open. The valve is returned to the closed position by a return spring.
The ECM uses the EGR position sensor to determine the position of the EGR valve. The ECM sends a reference voltage through the 5-volt reference circuit to the EGR position sensor. The ECM provides a voltage return path for the sensor through the low reference circuit. A variable voltage signal, based on the EGR valve position, is sent from the sensor to the ECM through the EGR position sensor signal circuit.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1369855&psdid=1058&evc=sm#ss2-1369855">EGR Valve Control Enabling Conditions.
Exhaust gas recirculation (EGR) valve control will only be enabled during idle and cruising conditions while the following conditions are met:
• The intake air temperature (IAT) is more than 5.25°C (41.5°F). EGR valve control will remain enabled until the IAT is less than 0°C (32°F) and will not enable again until the IAT is more than 5.25°C (41.5°F).
• The engine coolant temperature (ECT) is between 60-96.75°C (140-206.15°F). EGR valve control will remain enabled until the ECT is less than 57°C (134.6°F) or more than 99.75°C (211.55°F) and will not enable again until the ECT is between 60-96.75°C (140-206.15°F).
• The barometric pressure (BARO) is more than 74 kPa. EGR valve control will remain enabled until the BARO is less than 72 kPa and will not enable again until 74 kPa.
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