5.9 Cummings Turbo

[BFagan]

I have a 2004 Ram 2500 5.9 Cummings. My fuel milage has taken a sharp decrease. I normally get 23-18 mpg. Now it's less than 14 mpg. I have replaced the injection pump,the injectors, and the pump in the tank.
My turbo Is the OEM, I have over 281,000 miles on it.
How long do these turbochargers last? Could a weak turbocharger be my problem?
I would like anyone's input.

 

[sag2]

Did you actually diagnose the pump and injectors, or just assuming at your mileage they were due? Did it drop off gradually or all at once? Probably time to check the compression.

 

[cerberusiam]

If you want a useful dialog you are going to have to give a lot more information that what you have posted, there is simply no way to have a valid opinion based on what is there. Really need to know WHAT you are driving (04 or 04.5, 2x4 or 4x4, manual auto), HOW you are driving (stop and go, 75-80 mph, 50-60 mph, loaded, unloaded) WHERE you are driving (flat or hilly, high or low altitude, high or low ambient temps) WHEN you got this 18-23 mpg and how you calculate it. It all matters as well as what did you change? Tires? Fuel source? Programmer? ECM flash?

The 18-23 mpg is unrealistic for a 4x4 driven at interstate speeds of 70-80 mph in 80% of the US, you MIGHT see the low end of that in rare perfect conditions but that is not a valid average in most cases. Now, if that was an early 04 2x4 being driven at 55-60 in hot summer months at 3500-5000 ft altitude you might have a case. All the nuance stuff matters.

What you changed or did different is a big contributor? Change tires? Change fuel supplier? Get an ECM flash? Put new batteries in your calculator? Knee jerk reaction is you got it flashed and now the OH that has been lying for most of its life is now closer to true.

You replaced injectors, CP-3 and LP, why? Were there tests that indicated they were bad? Observed problems like dropping rail pressure, low boost, high EGT's, drive-ability issues? Who replaced the parts and what else did they do? What exact parts DID you use? New? Reman? No idea?

If you want to know if the turbo is good you need a boost gauge and baseline to compare. That baseline will differ if it is an early 04 or a late 04, need specifics on build date and engine ratings to know that.

 

[BFagan]

My 2500 was bought in September of 04. The injection pump was replaced because it was leaking (remanufactured) , the injectors were replaced because it developedloud diesel knock(remanufactured ), pump in the fuel tank was replaced because the fuel sending unit was bad. All these repairs were done at a Cummings authorized diesel repair shop. They will be doing a boost pressure test in the very near future. The ECM has not been flashed.
My truck is a 2wd and is driven mostly around town, I also pull a fifth wheel Rv. I don't know why you think 18-23 mpg is unrealistic, I have put every mile on it myself, so I'm sure I know what I get for milage.
Thanks everyone for your input.

 

[BFagan]

I bought my 2500 in September of 04 brand new,it's a 2wd with an automatic transmission.
It's mostly driven around town and on the highway at 70-75 mph. I live in the desert so it's flat land driving.
The injection pump was replaced because it was leaking (remanufactured), the injectors were replaced because it developed a diesel knock(remanufactured) and the in tank fuel pump was replaced because the fuel sending unit was bad (New). All work was done by a Cummings authorized repair shop. The ECM has not flashed. They will be doing a boost test this week.
My repair shop has the engine number, that should give us the baseline.
I have no driveability issues. The truck runs very good, I noticed a drop in milage and I'm checking everything. I might have another bad sending unit, the fuel pump is still under warranty. It could be because I have over 281,000 miles. I'm just making sure I don't have a serious problem. Such as loss of compression.

 

[BFagan]

I bought my 2500 in September 04, it's a 2wd with an automatic transmission. All repairs were done by a Cummings authorized shop. The injection pump was replaced because it was leaking (remanufactured) the injectors were replaced because it developed a diesel knock (remanufactured) the in tank fuel pump was replaced because the fuel sending unit was bad (New). I normally drive on flat roads and I tow a fifth wheel RV. Don't usually drive over 75mph.
I will be having a boost pressure test this week. The repair shop has my engine number, that should give us the baseline. My engine is the high output version 325 hp. I have been getting that milage for years. Hope this is enough information.

 

[cerberusiam]

Hmmm, maybe it has something to do with close to a million miles on a variety of trucks from coast to coast, border to border, in every season possible, and empty DD to towing. FYI, I don't use the lie-o-meter either, all hand calculated. I think I have a pretty good handle on what is realistic mileage and what isn't.

Did you read my post where I indicated you might have a case for spot mileage in that range if you had a 2x4 driving in specific conditions? If you are trying to say you get 18-23 mph pulling a 5'er then you might have a few more things to learn about realistic mileage expectations. You did not, and still have not, given enough info on your truck for anyone to guess at your problem. Note, it doesn't matter when you bought your truck as that does not indicate the MY. If it was brand new in September of 04 you have an 05 not an 04 as the MY05 models started delivering in August of 2004. In fact, if the build date on your truck is Jan 04 or later you have a completely different engine and programming tuner than prior to that. It makes a difference in a lot of things.

Remember, YOU came HERE looking for help not the other way around. If you are interested in actually learning something about your truck and how to recognize when you are being scammed by a "Cummins authorized diesel repair shop" that pretty much everywhere else refuses to work on these trucks because they do not have the correct software to diagnose anything then please answer the questions put forth with some attention to detail and honesty. You WILL get a lot of good info and experience if you help us help you just a little.

FYI, if you keep using reman parts to repair your truck you needn't look very far for the source of the stated problems. Evidently your "Cummins authorized diesel repair shop" hasn't exactly been honest with you about the service they are providing. If you care to learn more and educate yourself, we are bored with house arrest, ask away.

 

[BFagan]

I do not get that milage towing. I understand what your saying,I trained as an automotive technician out of high school, but I did not pursue that career. I'm a retired Firefighter and have driven multiple diesel truck's.
Thanks for your input!

 

[Killer223]

You have an 04.5 the HO indicates you have the 325 hp engine. not available to the early 04's. those have different injectors, pistons, programing, these are the details we need to be able to guess whats wrong with your truck form a keyboard. Cerb is about the best in the business. when he speaks, one should choose to listen.
you mileage drop could be and is likely junk injectors, yes replaced, ok with what? could be brakes dragging and needing more fuel, could be the torque converter not locking up, could be... could be... could be...
get it?

Oh and there is no G in Cummins.

 

[bighammer]

This variation in numbers really could be due to any reason, but it sounded like the focus was more on the CUMMINS engine, so I moved it here.

 

[SRay]

Different brands of tires themselves also contribute to mileage difference even if they’re the same size.

 

[cerberusiam]

Ok, now we know you have a 04.5 truck with the 325 engine. They were not known for great mileage at any time in any configuration without doing some tuning. Not that 18-23 is not doable, just not anywhere near an average or common. Your reported mileage for stop and go city driving where the truck rarely gets to run a constant rpm or get to and stay at operating temp is not usual, in fact it is far to the norm.

Being an auto truck throws some possibilities in there that might not be obvious at that mileage. Chiefly, TC lockup slipping and or OD slipping or direct clutches slipping. Running empty it might not be completely obvious something is wrong. I lost 2 mpg out of the blue with increased EGT's on a trip then spent the rest of it changing tunes and testing to see what happened. Turned out the direct clutch pack was on its way out and slipping EVEN THOUGH drive and OD felt fine. The pressure boost applied when the trans goes to OD was helping hold for a lot longer that it really should have a sit destroyed every steel and friction in the clutch pack and the only reason it quit working was it finally over extended the piston and cut the lip seal enough times it was getting reluctant to go into drive.

You have replaced parts with substandard units but given no time line on when compared to the perceived mileage drop. You also have not said if you hand calculating mileage or just reading the lie-o-meter. If mpg really DID drop precipitously then SOMETHING happened or some work was done that triggered it. You will have answer that os no but you knows the progression.

 

[seafish]

OP, if you have been reading the "lie-o-meter" to follow your MPG, you need too understand that the ones on these trucks are entirely unreliable and that then ANY myriad of changes and/or problems can easily effect the mpg numbers that you are seeing.

If you have been hand calculating your trucks MPG over a long period of time, then it will be slightly easier to diagnose your problems.

Please reply back and state clearly whether your MPG statement is based on hand calculation or on the lie-o-meter.

 

[bighammer]

Could also be a friend or neighbor got tired of dumping a can of fuel in it on a regular basis.

 

[TFucili]

My stock '05 would rarely sniff at 18. 23? Only if pushed out of a C5.

 

[AH64ID]

With all the mods to my 05 I wouldn't get 18-23, but the computer would tell me I was.

I had better tuning, cam, turbo, injectors, spin free hubs, etc... I could break 18 easy but rarely broke 20.


Also, there is no G in Cummins.

 

[KParsons]

my 06 auto, when new 19 to 20 on a long trip. that was the last time i ever saw 19.7 mpg.