05 VOLVO truck VED D12 engine lacks power and makes 4mpg.. what is wrong?

Having exact same issue..What did you figure out?

 

I believe if my memory serves me right his egr was stuck open.

 

I have same or similar problem with my Volvo. Have finally narrowed it down (I think) to a moisture related issue with the electronics. I kept it in my shop for 3 weeks and when we took it out it ran great until we ran it in the rain and it lost power as quickly as flipping a switch. This happened two days ago. We will concentrate on electrical wiring connections now and see what that does for us.
Martin

 

Check the wiring on the starter, the ground wire has been a problem going back to frame or the battery's, bad
EGR's will not effect the lost in fuel mileage or power that much.

 

Can you help me with the vacuum control modual location? I took the exhaust brake off and it seems to be fine. I am thinking the exhaust brake is being supplied air pressure when it shouldn't be, is that because of the VCM? When i start the truck and after about 15 seconds the exhaust changes tune and sounds like it is being restricted.

 

I am afraid this is normal. One of the functions of the VEB is warm hold Partial closing of the plunger so it increases engine back pressure thus warming up quicker.

 

Would a bad VEB let there be a partial closing all the time? The truck doesn't have the power it should. When i am driving empty and the engine brake switch is in the off position and you let up on the throttle the truck slows down like the exhaust brake is partially engaged. MPG is terrible 4.15 loaded and 4.5 empty. Running empty it takes miles to get to 75 mph and loaded cant even get to 65mph. Earlier in this thread it was said to change the EPG and the vacuum control module. As i said the EPG is fine.

 

was just looking and i understand the VEB is the system including the EPG and the VCB. What regulates the air pressure to the EPG? Could this be the problem that would supply air to the EPG continuously?

 

Sometimes the solenoid goes bad that operates EPG, it all depends what model truck you have, it might sit on the passenger side or the driver side. The air line to EPG also might have leak or crack in it and it's not letting EPG closing all the way.