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2011 mp8 shows 0psi aftertreatment fuel pressure


c-mac
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Well it seems like I'm always posting a doozie.  i have a 2011 with an MP8 that wont heat up when regenerating. It gets to about 600 degrees and thats it. I noticed that the aftertreatment fuel pressure was reading 0.0 and it would only hit 7% duty cycle, it would go back and fourth from 7 to 0 percent no higher. Well first thing I thought was the shutoff valve was bad. I installed a new block with shutoff valve and pressure sensor. No change. then I set it on a forced regen and cracked the line to the 7th injector and fuel sprayed out like it would with proper pressure. I blew out the fuel line from the filter base to the aftertreatment block and everything else you can think off. what i'm coming up with is, the ecm is not getting the signal from the pressure sensor or their's a problem with the ecm. Anyone else have this problem?

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It Is possible you could have a turbo issue If the turbo won't function correctly (sticking) the ecm ain't going to let the seventh injector have fuel! 

And it wont throw a code if the turbo is stuck! They just stick and teck tool is absolutely useless  to isolate  this problem! you Need to do manual checks. if indeed that is what is happening!

Edited by fjh
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I think I narrowed it down to a problem in the ecm or the short harness between the aftertreatment fuel pressure sensor to the ecm. I swapped the harness connectors from the oil pressure sensor and the a'treatment fuel pressure sensor.  While monitoring the a/treatment fuel pressure I started the engine and pressure still read 0.0psi. Then I activated the a'treatment shut off valve and the dash oil gauge went from 0 to 60 psi. I checked the harness connectors to both sensors, three pins one 5v one ground and I cant remember the third pin but the both were the same. I unplugged the ecm connectors to inspect for oil or maybe a terminal corroded or bent over. I looked all good. I'm pretty sure its an internal problem in the ecm.

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Ok, Im in another truck right now doing a forced regen and the intake manifold pressure is ranging from 1.8 to 2.0 psi. If I get back on the the truck in question, If I have similar intake pressure would you say that the turbo is doing what it should?

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In my notes on 2010 and up trucks, you should have 1.8 to 2 psi of boost during regen. Also did you do a DRV valve test? If its not working , temps wont get hot enough for a parked  regen. The early 2010 emissions engines had DRV valves,  Its the valve on the turbo output pipe, sometimes called a turbo by pass vave

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  • 2 years later...

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