[budman-mo]

Here is my question:

I have had a 95 12 valve, 2wd for awhile (240k) , it gets 21-22 mpg all the time.

I recently bought a real nice 01 24 valve, 2wd (97k), I haven't got a good fix on the mileage yet but it isn't close to the old one.

Both are automatics and seem to run about the same rpm so I assume they are geared alike.

You would think with electronic injection, 24 valve and all that the newer ones would do better.
I know the electronics help the bigger trucks get more mpg over the old style injector pumps?

Any suggestions on getting better mileage?

 

[Red Sleeper]

You would think with electronic injection, 24 valve and all that the newer ones would do better.

You just answered your own question. The P-Pump is the KING of injection pumps. And yes you would think the 24v would get better mileage than the 12v motors but thats just the opposite. I think it smainly because of te piston type pump on the 12v's. You ever notice how your 12v starts much quicker than your 24v? Thats because as soon as you start to turn the motor those pistons in the pump are moving and pumping fuel into the injectors and bam, its running. The VP44 pump is a rotary style and those kind you have to spin over a few times to get them to build pressure and send that fuel to the injectors. Just shows how much better the P-Pump is.

 

[OleTomCat]

So for Mileage, the 12V is better than the 24V?

Are there any other advantages or disadvantages to the 12V over the 24V?

 

[cmns2500]

otc, if ya want a g2 diesel, get a 98 12 valver

best of both worlds

12 valve motor and the upgraded int

and red, have you done yer fuel mileage yet?

i got 16~ mpg fer the trip

 

[budman-mo]

I understand the difference in the two, and know the 12 valve is a simpler engine but as I said with larger diesels the electronic injection gives more power and more mileage.
It makes sense with crank position sensors and a more precise delivery of fuel that it should do better.

I also have a 98 4900 International with a DT466E that I drive every day and it does much better (power and mileage) than the previous DTs that had a standard injection system like the 12v Cummins. I just wonder why the larger trucks run better and all with the electronic system but not the Cummins?

Anyone got any suggestions on what you can do to improve a 24v mileage?

 

[budman-mo]

Thought I would give an udate on this.

My "new" 2001 was doing 13-14 mpg all the time.
I ordered a fuel pressure light kit so I would know if I had lift pump problems.
I installed the kit and the light never went off, the lift pump was already out.
I checked it with a gauge and it was zero.
I went ahead and put on a lift pump and of course no difference in running or mpg.
Although I had no check engine light I decided to check for stored codes and found a 216.
Put on a new injector pump, added a Diablo puck and it gets better mpg and runs way better. Went 1300+ miles last weekend, mostly empty but the last 400 miles with aprox 2,000 lbs in the back and the overall agerage was 19.5 mpg.

I have learned one thing....
IF I ever buy another Cummins with a VP44 I will show up to check it out with my scan tool and a fuel pressure gauge in hand.
.

 

[strictly gravy]

What rear gears do you have?

 

[budman-mo]

Don't recall the exact ratio but 3:55 -3:56, same as my 95.

 

[strictly gravy]

Good deal. Same gears as me. I tend to get about 21-22 mpg unloaded on highway runs.

How do you like the power puck?

 

[pepsi71ocean]

the stock gears were 3.55"s, there was a 3.73 option i believe.

 

[cmns2500]

the axle ratios available were 3.55:1, and 4.10:1:teacher:

my rig has the 3.55's, and they SUCK w/ 35 in tires:tdwn:

 

[Red Sleeper]

Good to hear on your mileage man, glad it improved. I have been watching and readign bout the new module from Edge, the Mileage Max. I have yet to hear of anyone running it on their ride yet. Im curious what it actually does...