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2011 chu MP8 regeneration problems


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First off I have Vcads tech tool, Now, I have a 2011 Pinnacle with an MP8, the regen switch is flashing. It has a DTC -SPN 5443 Aftertreatment 1 hydrocarbon dosing system FMI7 mechanical system not responding properly. I hooked laptop up and to start regen so I can monitor temps and such. Before I could start the regen I noticed the aftertreatment fuel pressure was 101psi, engine fuel pressure is 55psi. not sure how that can be. When fuel dosing started the pressure dropped to 70 or so. Also this particular truck has the "aftertreatment module" and a hydrocarbon doser. Nearly all the trucks in our fleet have the 7th injector unit mounted to the exhaust. I'm not sure if this setup works a little different than what i'm used to. I started regen and the inlet and outlet temps didn't heat up like I think they should, about 600deg after plenty of time dosing fuel. I pulled the dosing nozzle from the exhaust, cleaned and ran test. Nothing cam out, I had pressure, it started blowing out where the fuel line screws on. I just didn't have it tight. If it was't for the high aftertreatment pressure I'd say the nozzle is just clogged. I think that i'm going to order that dosing nozzle. what do ya'll think?

Edited by c-mac
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Best advice I can give is since you have ptt2, I would follow guided diagnostics for that fault. You have to flow test the nozzle to determine if it is bad but since they are relatively cheap its not a huge loss if that wasn't the problem.

The fault with that fmi lists 3 possible causes: 1-fuel line(either kinked or plugged), 2- plugged doser valve , 3: bad aftertreatment hydrocabon dosing module. 

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