Poor Mileage on 325/505

[cvincent]

My dad has an 05 dually 4x4 4 door with approx. 25K miles on it. Has 325/505 engine (build date Aug. 2004, which makes it past the tsb for mileage, etc. , according to the dealer), 48RE transmission, 3. 73 gears, truck is bone stock. The problem is mileage from a low of 4, pulling a 22' CC boat to Florida, averages 9-10 pulling a 20' enclosed car hauler to a high of 14. 8 running empty. He's ready to go back to his duramax, says maybe he should not have listened to my recommendation about my history with the 4 - 2nd gen trucks I have on the farm. Any and all help would be greatly appreciated. He's not looking for a lot of extra power, just better mileage. He doesn't want to have to look at a lot of guages, just drive the truck. Dealer says there is nothing they can do. Many thanks !!



Clay

99 3500QC, Alcoa wheels, 3. 54 gears, Blue Chip FMS, 5 sp.

 

[WoodChuck]

They never made a 325/505 engine. I've got a 305/555 with auto and the best mileage I've seen is 25 mpg for 1 hr. at 65mph steady and flat. and 23 mpg driving 300 miles home from Nevada. And 12. 2 towing a 28' TT over 1200 miles from LA to Reno and back.

Sorry I can't help but I don't believe 4 mpg is even possible with a CTD unless you're drag racing or sled pulling.

 

[Turbo_Bob]

My 03. 5 with 305/555 engine, 3500, 2 wheel drive, 3. 73, 6 speed gets 21 MPG solo and 11. 5 to 14 towing a 7000 pound enclosed car hauler depending how fast I drive.

 

[cvincent]

Correction

Engine is the latest, greatest 325 that meets Fed emission reg's. And ,YES, 4 mpg is correct, hand calculated personally.



Clay

 

[Sarge]

Well the 4 MPG was a fluke most likely, but the rest of the mileage is pretty accurate. His truck is nearly the same as mine, except for the 48RE and the 3. 54 gears. The nv5600 and the 4. 10's are much better for towing. However, what he has to realize is that he is probably hovering around 9000# pounds empty. The dually, the 4X4, and the auto are all killers of MPG. Put a ROKKTECK crank position sensor in it for a bump of 1 - 2 MPG. Keep the tires inflated, and the speed down. 60 to 65 MPH is reasonable for towing. The cat on these trucks, along with the 3rd injection event to control emmissions all work against mileage.



He bought a big, heavy duty truck. It's not going to roll like a 1/2 ton 2 wheel drive short bed. All of the new trucks make by the big three are under the same emmissions regulations, and each goes about it a little differently, but the results are the same. There is no magic, just some alternatives. Is it comfortable? Does it run good? Then slow down and enjoy the ride. Or sell it and get a 1980 Toyota... ... ... ... .

 

[Bob4x4]

I just got back from the Palmdale event,I avgd 13. 5 towing my 25 ft tt and making about a dozen 1/4 mile passes. 4. 10's and 3. 15 tires on the 05 auto. You can go into the ECM and ck idle time,fuel burnt at idle and many other bits of data to understand your mileage numbers.



Bob

 

[Matt400]

Engine is the latest, greatest 325 that meets Fed emission reg's.

Must be 325/610

 

[Sarge]

Yep, the dually, one ton, and stock tires make a difference. As well as not hauling a high profile rig... ... ... .

 

[cvincent]

For the record, My Dad's previous truck was an 03 Duramax dually 4 door 4x4 that averaged around 18 +/-. With a 2000 acre vegetable farming operation, I have considerable diesel experience(68 engines in service, at last count, from 2 cyl. Deutz irrigation engines to N-14 500HP Cummins). We currently have 9- 5. 9 Cummins in tractors, backhoes and Dodges. It just seems that this particular truck ought to do better than it does. I appreciate all your help, I'm just looking for ways to make it better, if that's possible. I ragged on him about the duramax until he decided to go my way, and now I'm having to listen to him compare the duramax against the Dodge. I can't stand it!!



Clay

 

[2Gen3Gen]

There is no magic, just some alternatives. Is it comfortable? Does it run good? Then slow down and enjoy the ride. Or sell it and get a 1980 Toyota... ... ... ... .

Ive owned several Toyotas and it is very rare to get anything above 18mpg. If you put anything besides stock tires on one, your mileage is in the toilet, along with your clutch, which you have to slip just to get it going. :-laf

 

[stokede]

What to say

Tell him if he can find a better truck, then buy it.



And go on... . :-laf

 

[cerberusiam]

I didn't think it was possible to make a stock Cummins get 4 mpg. Unless it was a fluke or math error, I would start looking for some major problems in the fuel system and would be concerned a lot of that fuel is in the crank case.

 

[tschwab]

For the record, My Dad's previous truck was an 03 Duramax dually 4 door 4x4 that averaged around 18 +/-. With a 2000 acre vegetable farming operation, I have considerable diesel experience(68 engines in service, at last count, from 2 cyl. Deutz irrigation engines to N-14 500HP Cummins). We currently have 9- 5. 9 Cummins in tractors, backhoes and Dodges. It just seems that this particular truck ought to do better than it does. I appreciate all your help, I'm just looking for ways to make it better, if that's possible. I ragged on him about the duramax until he decided to go my way, and now I'm having to listen to him compare the duramax against the Dodge. I can't stand it!!



Clay

One word explains it: EMISSIONS! In 2004. 5 ALL manufacturers had to meet much tighter emmisions. My '98 got better mileage than my '05, but with the improvements in the 3G I have never looked back. IF your dad wants to sacrifice progress & creature comfort for mileage he will need to buy an older pre 2004. 5 model year.



However - Dually/auto/4x4 is the absolute worst combo for mileage. I am averaging 12-13 mpg towing my fiver, about 10,500-11,000 lbs loaded through the mountains, pretty pleased with that.

 

[JonathanBurk]

Not sure what the Dually Duramax gets but my Uncles 7. 3L Powerstroke dually is getting in the 13's unloaded. I think Dually's are just super heavy, not a lot of hope for spectacular mileage in them with today's emission standards.

 

[Alan Reagan]

There's a few things he can check. First, check the pressure hoses in the charge air system and make sure the hose clamps are all tight. Then make sure the top to the intake plenum is torqued down to spec.



At 25K he should have changed the air filter by now. And he's not far off from a fuel filter change.



The D-Max doesn't get better mpg based on the owners, I've talked to. At best, it's comparable.



Finally, the 3. 73 rear is not helping his towing mileage. My personal experience is that 4. 10s get better mileage and pull stronger. I regret not going with 4. 10s on my 05.

 

[CajunDieselMan]

It is possible to get 4 MPG if someone siphons the fuel out of your tank. My cousin had that happen--he was getting 16-18 mpg and one time it went down to 6. 5 for no reason. He had just washed the truck, but there was diesel fuel down the side of the truck. I've been meaning to get a locking cap since then.

 

[Drewhenry]

poor mileage

I knew an individual who towed a 16ft johnboat from Texas to Alaska and back. He complained about 6mpg. I then found out that he had his dodge auto's overdrive turned off because he thought he needed to. Have you been running with the OD turned off ? Also may need to get an anti-kickdown switch to keep transmission from shifting out of OD. Just my thoughts. Hope this helps.

 

[jimnance]

One word explains it: EMISSIONS! In 2004. 5 ALL manufacturers had to meet much tighter emmisions. My '98 got better mileage than my '05, but with the improvements in the 3G I have never looked back. IF your dad wants to sacrifice progress & creature comfort for mileage he will need to buy an older pre 2004. 5 model year.



However - Dually/auto/4x4 is the absolute worst combo for mileage. I am averaging 12-13 mpg towing my fiver, about 10,500-11,000 lbs loaded through the mountains, pretty pleased with that.

I'd be pleased too! Pulling my 14K triple axle high profile fiver with my '03 six speed I averaged right at 10 MPG in mountainous Oregon, and 11 MPG on the flats. With my new rig I'm down to 9 MPG in the mountains. On the highway at 70 MPG empty I'm hovering around 15 MPG. Around town (rural area) I'm also averaging 15 MPG. I'm disappointed, but not surprised. The 4X4 Q. C. Dually is very heavy and has more induced and parasitic drag than a 3/4 ton SRW.



I'm certain that emissions play a big part too.

 

[jacqnbill]

I have a Rokktecon ebaywhich exoires in three hours.



http://cgi.ebay.com/ebaymotors/ws/e...d=1,1&item=8034278604&sspagename=STRK:MESE:IT