c-mac Posted October 16, 2016 Share Posted October 16, 2016 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? Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/ Share on other sites More sharing options...
Macktech689 Posted October 16, 2016 Share Posted October 16, 2016 I would start with checking the sensor 5V. supply, ground and signal voltage. Do it first at the sensor and if everything is OK check at the ECM connector, may be a wiring problem. Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-348880 Share on other sites More sharing options...
fjh Posted October 16, 2016 Share Posted October 16, 2016 (edited) 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 October 16, 2016 by fjh Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-348919 Share on other sites More sharing options...
c-mac Posted October 17, 2016 Author Share Posted October 17, 2016 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. Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-348961 Share on other sites More sharing options...
fjh Posted October 17, 2016 Share Posted October 17, 2016 I beleive you would be throwing up code if that were the case iif the turbo won't make air the ecm will hold out triggering fuel to number 7 !it will try to regen then stop Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-348994 Share on other sites More sharing options...
c-mac Posted October 17, 2016 Author Share Posted October 17, 2016 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? Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-349015 Share on other sites More sharing options...
fjh Posted October 17, 2016 Share Posted October 17, 2016 (edited) Thats A deceant plan! Just didnt want you to rule it out is all we have chased this many times and alot of times it ends up being the turbo. Edited October 17, 2016 by fjh Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-349031 Share on other sites More sharing options...
Mackpro Posted October 17, 2016 Share Posted October 17, 2016 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 Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-349051 Share on other sites More sharing options...
Mackpro Posted October 17, 2016 Share Posted October 17, 2016 Here's a some tips that a guy at Mack sent me years ago. scan0310.pdf 1 Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-349052 Share on other sites More sharing options...
fjh Posted October 17, 2016 Share Posted October 17, 2016 Good info bro thanx for posting way more then you would get from Teck support! Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-349067 Share on other sites More sharing options...
duranandsons Posted July 25, 2019 Share Posted July 25, 2019 How can I a get a copy of Scan0310.pdf. from Mackpro? Quote Link to comment https://www.bigmacktrucks.com/topic/47268-2011-mp8-shows-0psi-aftertreatment-fuel-pressure/#findComment-428718 Share on other sites More sharing options...
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