[Usaemtp]

Hello, I'm new to diesel trucks so bear with me please. I bought an 04 2500 turbo diesel with 139k miles, to pull my toy hauler with. The thing was getting about 23 mpg without load in Dec and was getting about 10-11 mpg with the trailer. It always emitted a bit of black smoke on acceleration from stop but not much after that. Now it really smokes black and does so most of the time. At times on cruising on hwy the smoke is grayish black, darkening up with acceleration. I have also noticed that he mileage while towing is down around 8 mpg and sometimes less. I hear no new noises, just the typical high pitched whistle of the diesel engine while driving. There is no boost gauge on the turbo and I am ordering one to install on it. What could be the problem with this truck? Did I get taken by he guy who sold it to me? I expected a little smoke butI have talked to other people with this same truck who say that they get much better mpg towing (around 15 with same weight trailor) and little or no smoke, and around 25 mpg highway without load. Any thoughts?

Brian

 

[RichT]

have you checked your air filter? and air inlet restriction will cause poor performance and black smoke

 

[Usaemtp]

Thanks for the reply. Yes I cleaned the filter (previous owner had installed an Airaid filter on it) and changed the oil just last week but got no change in the issue. Near as I can tell this is the only modification that has been done to this truck.

 

[RichT]

Well I mean you're going to get black smoke with a diesel but it shouldn't be a ton. I don't think it's an injector problem does your oil level stay the same or go up? Starts and runs smooth?

 

[Usaemtp]

It's a lot of smoke and worsening, along with decrease in mileage and no visible change in oil level. I forgot to mention that I also noticed last night, for the first time, that after starting there was oily soot, some of the drops wet, on the driveway behind the exhaust.

Brian

 

[RichT]

That could just be condensation coming out of the exhaust. And I think there's a tsb update the dealer can flash for less smoke but that might only be for col starts I can't remember

 

[Dave617]

have you changed the fuel filter also?

 

[DieselPlower]

Do you know if this truck is an 04 or an 04.5?
Are you getting your mpg off the overhead?
There will be a bit more smoke as it gets warmer out because warm air is not as dense.

 

[JTS05Cummins]

Just my 2 cents but if its got the stock exhaust you shouldnt see hardly any smoke and at highway speeds even with a straight pipe getting on it you should hardly see any smoke with stock tuning and fueling... also check the high pressure boot coming off the compressor. These have been known to burst while getting into it loaded giving you less boost. You can try revving the truck in park after its warmed up to see if you have an injector hanging open.. When your rpms are coming down off rev the rpm's will not drop at a constant rate. that will tell you one of the injectors is open when it hits the compression stroke on that cylinder because it has fuel in there... Just a thought....

 

[JTS05Cummins]

also, do your mpg calculations by hand... the overheads displays are generally off by a few mpgs. mine says 21.8 hand calculated im getting 17..

 

[Usaemtp]

Hello all and thanks so much for the input. I am not sure if the truck is an 04 or 04.5. I have not yet changed the fuel filter but am going to do that this week when I get back in town. I am also installing a boost guage on the turbo (but need to know what normal range is for boost). I will check that high pressure boot and try the revving test to look for a missing injector. Are there any other tests for injectors? I am doing the calculations for mpg by hand. Also, what is meant by "stock tuning and fueling" on a diesel? What adjustments can be made to tuning?

My truck bed has a bedliner in it that the last owner put in. I knew it was to cover up the rough bed (it was a work truck for a painter) but when I was looking under the truck near the fuel tank a while back I found they had cut a square out of the bed to access the pick up pump in the tank. I don't know if this means that pump is new or was serviced but am guessing that filter is good. Anyone know how much fuel pressure I should have? Should I plumb a pressure gauge in there as well?

I am scratching my head a lot. I know diesels smoke a little but this thing has become a smoking beast and smokes constantly, much more than anyone else who I've spoken to who owns one. My camper visibly greys on that side when I pull it.

 

[steelhead01]

go with JTS05

fuel filters do not cause diesel black exh. smoke

most likely boost leak or low boost. hoses, intercooler, grid heater gasket seal, boost sensor tits up, or turbo on it's last legs dusted worn blades etc, turbo shaft coke build up