Exhaust Back Pressure

John Diagnostician Butler, Pennsylvania Posted   Latest  
Question
Driveability
2012 Ram 3500 Laramie 6.7L (L ETJ) 6-spd (66RFE)
Lack of Power

I am not a diesel guy.. When I arrived the exhaust had a whistle sound coming from it, it sounds like it had a plugged or restriction in it. The back pressure pid was reading 30 psi at idle and when I did a snap throttle it would go considerably higher. So I am thinking the exhaust brake is stuck on. After several starts it dropped to 15 psi and the exhaust sounds normal. Can someone tell me a spec on exhaust back pressure? Is the exhaust brake still stuck on with having 15psi at idle? Took a ride around the block and it has lots of power but customer still don't think its 100% I noticed exhaust pressure going up to 45psi under accel. There is no exhaust treatment installed it is straight pipe from turbo to tailpipe. Egr delete. Thanks guys

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Albin Diagnostician
Leavenworth, Washington
Albin
 

Did you verify correct operation of the variable vane turbocharger? there are scan tool tests for that, and several TSB;s written about those problems.

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John Diagnostician
Butler, Pennsylvania
John
   

No I didn't I was looking for that but couldn't find it on my verus. Thanks I will look at tsb's I looked quickly for wiring diagram for the vvt to manually activate the vvt but was unable to locate them. Now I have some time today I will look again

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Jess Diagnostician
Windsor, Wisconsin
Jess
 

The exhaust is going to show backpressure using factory sensor. Which is in manifold. I can't remember if sensor is reading atmospheric or gauge pressure. On the Dodge. At koeo does the sensor read in 14's for psi. If so that is not much for when engine is running. If truck builds 30 pounds boost 45psi backpressure is normal at exhaust manifold. In regards to exhaust brake I some can have…

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John Diagnostician
Butler, Pennsylvania
John
 

Thanks Jess I cant say for sure but I do think it was reading 14 at koeo and I thought that would be baro pressure, but I didn't know if it would have back pressure under accel, but the engine was cold and I do remember reading somewhere that it might close the exhaust a little to warm the engine. That all makes sense now. How can I determine if the turbo vanes were stuck or the actuator itself…

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Jess Diagnostician
Windsor, Wisconsin
Jess
 

The turbo is Run by datalink via The pcm. The service bulletin I seen requires Dodge Tech connect to go through the steps. Attached is Troubleshooting for code P0046 Giving you idea of Wiring and some tests. My Verus is at Work so I can't look what options you have Available. If you have Engine serial number on hand I can Also look on Cummins for bulletins and repair.

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Caleb Technician
Mishawaka, Indiana
Caleb
 

Are there any codes?? Can you verify low power by first doing a volumetric efficiency test for us and displaying the results? After that yes it sounds like the exhaust pressure sensor in the manifold is working correctly . Remember exhaust pressure before the turbine wheel and boost should match. So 45 -14 is 31 psi. If look at the MAP it should display 31 psi in boost or 31 psi above…

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