As for my truck the average is 12.5 MPG. Then again I did'nt buy it for fuel economy.

03 3500 Dually SLT, 48RE with HO, 4X4 QC with 4.10 gears

You can't get bad mileage, you don't have a 600!

 

Wait till I get my SRT-10 I think average on that is about 12 MPG.

 

the timing on most diesels is retarded to reduce cylinder temps to reduce the formation of NOx however the cam is gear driven on the front of the engine and if I'm not mistaken there is a dowl pin in the gear so it can only be put on in one position that can't be screwed up eaisly the change in timing is advanced in the fuel injection which is controlled by the ECM if there is a timing problem this is where it is.

 

True but what if the 600's cam gear had the dowel located a few degrees retarded than the 555. Would be interesting to compare part numbers of the gear and also the cam on all of the various 3rd gen configs. just to see if there is any mechanical differences.

 

There are three possibile causes for poor mileage.

1) Mechanical
2) Electronic
3) Human

Mechanical can mean dragging brakes to misaligned crank position sensor to bad injector to bad fuel pressure sending unit etc., etc..

Electronic is, in this definition, software programming and ECM communication related.

Human refers to the driver, not the guy that may have assembled the motor parts wrong or written the software wrong.

Assuming all the recent 600s get the same software, which is more likely to be identical than the hardware, if the software were the cause of bad mileage, we would all be getting the same mileage.

Tolerances in machines and parts are a fact of life. No two parts are identical. They are only very similar. No two sensors are identical. No two gears are identical. No two cranks are identical. No two injectors are identical. This is the second most likely area for significant variation.

Human error is the most likely area for significant variance. To eliminate human error, the good mileage guys would have to swap trucks (identically equipped trucks) with the lousy mileage guys and see what happens.

If new software comes out that offers say 6 mpg better, we should all get that much better mileage. Those getting 12 would get 18, and those getting 17 would get 23. (I could live with 23.) If that doesn't happen, then the cause of the poor mileage is either mechanical or human. Or both.

For those poor guys who drive for mileage and don't get it, the software won't hurt, but I'm thinking there's more to it than just software. Cam gears, timing, sensors, injectors or something else is somewhat at fault. That is the luck of the draw. Now you have to play the cards in your hand. The difference here is that you can see the whole deck and get to choose which cards you want to pick up and/or put down.

Do you pick up the BHAF, the TAG, the 51" muffler? Do you go for the injectors? Do you add a box? Do you look at the sensor locations? Right now you just ***** as loud as you can and hope DC gives you a better hand for free. After that I do the first four above. After that (or before) I take a driving course.

YMMV

 

I just ran a similar trip as to the 580 mile one with the volumizer on level two. This time it was on level one which is the off positon.
Volumizer level 2 21.9
Volumizer level 1 22.7
There may have been a little driving differences to make the 22.7 higher , less idiling, more two lane 55mph, but both trips were over 450 miles, not much difference in mileage for the extra power.

I have a modified air box, TAG, volumizer, and 4 inch DPPI, peragon bed cover

I was getting 21 the first month. And I have gotten better, but 21-22 normal on long trips.

 

The cam mark did not change from 03. The injection timing is totally controlled by the ECM and yes, it is retarded for the 600 to help control emissions. you can buy a box now that will give more fuel and change timing. I have not heard of aftermarket camshafts, but it surprises me that there are not any. I have been told by a very knowledgeable diesel mechanic that you can put the common rail camshaft from the 2003/4 engines in a VP44 engine for a large improvement in overall everything, but have not tried it myself. I am happy with 21MPG and don't want to fix what's not broken. I am most suspect of injectors.

 

Bigblock, I tend to agree with you there on all three points.

With regard to the timing, the third injection event is apparently to get or keep the CAT at catalyzing temperature. Not too sure why it's needed after it's warm or above 1/4 throttle, though. Seems like a waste.

I'm not knowledgeable enough to understand why the timing had to be retarded as well. I do know that it's retarded to burn more fuel for the same number of miles and call it good for the environment. That's more pollution no matter how you slice it.

So what's the best/safest/cheapest way to advance the timing????

What're the detais on your truck?

 

the best way to advance timing on these engines is through the ECM if there is a best way. the dumbest thing to do on an electroniclly controlled engine is to change the mechanical componets as a new program has to be written for the truck to even run trust me its not easy or fun to do (went to school for this) retarted timing is not really a bad thing actually allows for better milage but harder to accelarate. Cummins is on top of what they do the problem extends from what DC thinks you want . You demand power and acceleration they gave it to you the key to solving your problems is to demand efficency if DC is hurt finacially they will cave to the market demand those who want extra power will always add it on later It is not a very complicated issue remember Keep It Simple Stupid