Down To 4.4 MPG??????

[Papa Rick]

Checked my mpg tonight and it is down to 4.4mpg???? Man what the heck is happening????

Went back to my old vendor and it didn't make a difference, changed the air filters, didn't make a difference. (they needed changing)

Called KW Dealership and they told me the only thing they knew it might be is overhead run. I asked them would this make it loose 1 1/2 mpg and they said never heard of it doing that much.

It isn't skipping or loosing power. I ran 327 miles today and it took 73 gal, which comes out to 4.47

Should the Dealership be able to plug it up to the computer and find something out?

ANYONE HAVE ANY SUGGESTIONS???????

[GMAN]

They can connect to the trucks computer and see how the injectors are performing, see if there are any codes and a number of other things about the truck. If you have changed the filers and are still getting poor fuel mileage that would be my next step. It should not cost much to have it checked. 4.4 is a huge drop. :shock:

[Papa Rick]

Thanks GMAN that is what I thought. I didn't want them just to do the overhead until they ran the check on the computer. The drop from 6 to 4.4 for 327 miles cost me $ 55.48 more. In one week of 2000 miles the difference is $362.42 WOW that hurt!

[GMAN]

I would have the cpu checked before having the overhead run. Any of the major truck or engine dealers can check it for you. Southeast Diesel in Chattanooga can also check it. It only takes a few minutes and would probably cost less than the difference in what you spend on fuel on that 327 miles.

[Bobby]

Is this a single turbo C15... or twin turbo ?

[Sonny Pruitt]

buy fuel somewhere else
see if there is a difference
(may be bad fuel or someone tampering with the pump?)
dump some diesel clean in to boost cetane
see if that makes a dif
are you sure your odometer is accurate
lock your fuel cap

[Papa Rick]

Took the Truck to the shop today and they ran the computer on it and nothing showed up. The fuel mileage showed 5.46 avg. I told them it was above that when I bought it 9-28-07, and that I had been avg 6.0.

They reset the computer (Cost $90.00 Labor to do this) Guess they have to make money, but not this much!

Requested they take an oil sample and send it off and see what it tells me if anything.

Service MGR said they could run overhead, but he would run it 1 more week with the computer reset and see if it shows the 4.4 avg.

Was told that I could have got some ultra low sulphar fuel, and this could cause the big drop.

Where I fuel most of the time has the low sulfur sign but not ultra low. The place that I got fuel at and it started dropping, I am not sure if it is ultra or not, but will find out.

Bobby Posted: Sat Oct 20, 2007 7:43 am Post subject:

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Is this a single turbo C15... or twin turbo ?

Single Turbo C-15

Sonny Pruitt Posted: Sat Oct 20, 2007 5:29 pm Post subject:

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buy fuel somewhere else
see if there is a difference
(may be bad fuel or someone tampering with the pump?)
dump some diesel clean in to boost cetane
see if that makes a dif
are you sure your odometer is accurate
lock your fuel cap

Odometer is correct as we on a pay per ton by mile, so the places I go have distances already set and I check it to make sure I am getting my pay right.


If I got some bad fuel could it cause the following on mpg. Starting on
10-14 I bought fuel at a different place. Before that here is the fuel mileage avg:

10-3-7 411 miles 72.28 gal 5.68mpg
10-8-7 477 miles 81.17 gal 5.87 mpg
10-13-7 491 miles 83.15 gal 5.90 mpg

Switched vendors

10-14-7 666 miles 116.02 gal 5.74 mpg
10-15-7 655 miles 119.00 gal 5.50 mpg
10-16-7 654 miles 125.70 gal 5.20 mpg

Switched back to original vendor I have used for the past 6 months

10-18-7 562 miles 106.99 gal 5.25 mpg
10-19-7 327 miles 73.02 gal 4.48 mpg

Hope this will turn around soon!

Anyone have any suggestions that have not already been posted, I WOULD greatly apprecaite it very much.

[Blind Driver]

I'll throw something in here:

Brakes sticking, everything lubed? Something might be dragging...somewhere.

Has a compression test been done on the engine? Hopefully you won't find anything excessive in the oil analysis.

[Papa Rick]

Blind Driver Posted: Sat Oct 20, 2007 9:28 pm Post subject:

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I'll throw something in here:

Brakes sticking, everything lubed? Something might be dragging...somewhere.

Has a compression test been done on the engine? Hopefully you won't find anything excessive in the oil analysis.

Checked for anything sticking, just had the truck serviced less than 6000 back and ran dyno on it same time, nothing showed up. Had the oil checked when truck was serviced and nothing showed up.

[GMAN]

Well now, this is quite a dilemma. Perhaps it is something as simple as your fuel. It seems odd that your fuel mileage would be affected that much. :?

[Papa Rick]

Anyone ever heard of a Charge Air Cooler going bad and causing this much drop in mpg?

[Papa Rick]

Southeast Diesel in Chattanooga

GMAN, have you had any dealings with them, do you know if they are open on Saturdays. Do you have a Phone Number.

Thanks GMAN.

[GMAN]

I have dealt with them in the past. They are not cheap, but usually charge less than the local dealers. I don't believe they are open on the weekend, but their number is 423-622-1006.

[Blind Driver]

Have you noticed a loss of power?

I had some sort of nest sucked up into my turbo. Whatever was in it, damaged the impeller. I'll bet I lost 50 hp and some fuel mileage. Going to replace the turbo someday.

Possible restriction in the intercooler?
Maybe something in the air intake system?
Have you noticed any increase of black exhaust?
Is there air pressure in your tires correct? Maybe some goober is playing jokes.

[sidman82]

If you have a boost gauge, what's it doing? Yes, you would lose mpg if you had an air leak somewhere in the charge air cooler.(intercooler)same thing. Make sure all your hoses and conections to your air cooler are secure and tight. What about the turbo? Sometimes they can slowly crap out on you and you would lose mpg.

[allan5oh]

Yes, check the charge air cooler.

They block both sides, pressurize it to about 30 psi, and notice the boost loss over about 15 seconds. Do this ASAP.

If it's more then 3 psi, change it.

Also, I think sonny is giving some excellent advice, someone may be skimming your fuel.

You changed fuel filters as well correct?

ULSD doesn't affect fuel mileage that much. I run it almost exclusively and my fuel mileage this year is the best ever.

[kos]

Hi Papa Rick! did you find the problem? What was it?
I have the same problem C-15 -4.4 mpg before i got 5.5-6 mpg!!!

[Bandit102]

Dual turbo? I'd sure have a look if so. A friend of mine keeps losing the top turbo, don't know why. But it does knock the hell out of his mpg. He says there is a big power difference though, of course he runs pretty hard too.

[Orangetxguy]

See all the different things that can affect the fuel economy of an engine.

Now...weak turbo has been suggested...that can be tested.

Charge Air system leaking...that can be tested.

Fuel filter dirty? That can be changed.

Rack needs to be run? Well..they will see how far out of sinc the injectors are, when they tear into them. My rack cost me $469.00 to have done.


Now...on the fuel portion of the equation. Are all the hoses in good condition? Any wet spots? I wouldn't have believed it, but something as simple as a weak hose can lower your mpg with an electronic engine.

Another thing that lowers fuel economy is Bio-diesel, especially the 855 blend. You can lose 1/2 mpg with that stuff easy. I try to avoid it as much as possible.

[SoCal79]

There are a few guys around here that bought new trucks with the C15 and have the same complaint, economy seems to get worse the more miles you put on it, they all have less than 300k. One guy said Cat put out a tech bulletin and even a video on how to drive the C15 for best fuel economy, dont know if its true or not but you may check with Cat for a tech bulletin.