Hi everyone I have a problem.. Just bought 05 Volvo 630 with VED D12 465HP engine, 10 speed auto-shift, 630k miles. Truck averages 4mpg and totally has no power on higher gears( 7-10) Low gears are quite ok but still not the way it supposed to be. On flat road it takes really long time to change it from 9th to 10th gear. Went to the dealer to check codes - no codes at all. Turbo boost under higher rpm shows a little over 30. The only thing that is totally unclear is fuel pressure.. VCADS software shows 32 psi on idle and 64 at higher throttle like 1650 rpm. Dealer says it suppose to be around 45 at idle and over 60 a high rpm, when I call VOLVO of US hot-line they give me 15 psi and 45. I have to mention that my friend has exactly same engine and his truck averages over 6 mpg and in his truck response to throttle pedal is like in some sports cars comparing to mine truck.
I've changed oil fuel air and antifreeze filters, adjusted valves and checked injectors by disconnecting them one at the time with the VACDS software.. EGR valves been changed 60k miles ago and dont give any codes so I consider them to be OK
Cant tell if engine takes oil but pipes that goes from valve cover are clean and no smoke is coming out of them like I saw on some Detroit engines.
Today I'm going to check physically fuel pressure after the pump.. but still not sure what pressure is the right one for this engine and if its too high could it hurt the engine?
Any suggestions will be greatly appreciated.
05 VOLVO truck VED D12 engine lacks power and makes 4mpg.. what is wrong?
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Just checked fuel pressure and compared it with another non-problematic truck with volvo D12 engine.. both pressures are exactly the same..
Could it be faulty ECU or some timing sensors if there are any?
I read something about DEGRADED mode.. what is it and how would I know if my engine is in one??
Your fuel pressure sounds correct. And your boost pressure sounds good. I didnt know Volvo engines had a Degraded mode, atleast I have never seen it. But to answer your question what is it - derate can in my experience (on other vehicles) happen two ways. One is if the ECM detects a problem with a system, example of this would be high coolant temperature, not critically high, but high enough that the ecm turns the power down on the engine to try to reduce the temperature before it reaches a critical stage where the engine will shut down. I wouldnt think this would be the case on yours because that would flag a check engine code.
The other way to get an engine derate is thorugh the Datalink network - some systems have the ability to derate the engine. One is the ABS/ATC and on some models if it has a auto trans(not a autoshift manual, a true auto trans). Both systems ABS/ATC and auto trans have the ability to reduce the engines power dramatically.
On a problem with a C9 cat the engine was on the dyno and showed about 200HP under rated hp, because the ABS/ATC system was putting it in a derate. It didnt show up on the CAT ET software. This is just an example of what I have seen.
The temperature seems to be normal 170 goes up to 200 in traffic with fan bringing it down to 170 again and it cycles but once on the flat highway it doesn't go above 170 degrees ..
my transmission is autoshift with 3 pedals so I dont consider it full auto I guess
Just from experience, I did an lot of, asking questions at my Volvo dearler this what I found out before I bought my 07 780 with auto shift.
The trans can have up too three versions of software that can download to it, like
Basic Enhanced Basic Fuel Economy 'Basic' shifter - no manual shift buttons on the gearshift knob, no "E/P" Economy/Performance button.
Also check which firmware is in the engine ECM
If you don't ask for it, Volvo will not tell you any thing.
I would sugest dyno that way you will get a better picture of what's really going on.But let me tell you I don't know how heavy your loads are but this setup is kind of weak for loads over 35000 and it will pull but it lacks power and strugles and mpg drops.The auto trany is suppose to read the data as far as load weight and driving conditions and adjust to that.Also the way you drive it can be a factor too you have to kind of help it shift,speed up a little before you star climbing that hill but in most cases you'll be the last one on the top depending on your weight and also your differential ratio.And if you keep flooring the gas pedal it will only burn more fuel it won't go any faster.But you may also have a leak somewhere it could be sucking air Or exaust leak or something that causes this.I have an 07 780 d12 engine eaton 10 speed fully automatic and geting 6.8 to 7.5 mpg with minimum idling.My differentials are 3.42 and my loads are arround 20000 but when I get a 39000 pound load its another story.The other day 5mpg Boston to Charlotte via i-81 39000 in the box.Just an example.But I would dyno it and go from there and I wish you good luck
go into data log and look up lifetime mpg to compare to yours now. If it's close to the same get rid if it. I own ten 06 and 07 volvos 6 with D12s four with D16. Volvos will suck the life out of you chasing power and mpg problems. Find a good tech if he / she can't find the problem easily my experience has been it won't get better no matter how much you spend.
I pull flatbed with 49k pounds loads, before I also have volvo with N14 430HP engine and this two trucks are so different.. N14 engine has faster response to the throttle and is much stronger than VED D12 engine.. So definitely something is wrong.. My mechanic says engine works like it has misfire, not working on all cylinders.. I guess will have to open it up and check, like Pablo said - for tossed valves or bad injectors.. eventually engine wiring harness might have circuit but I'm all stupid now.. it's been a month and still didn't fix the truck..
My data log shows average of almost 6mpg but with a lot of idle hours ( work hrs 20k to idle 8k hours over the life of the engine ) so I guess in the past everything was alright..
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