LLY Help

[rickdlance]

I have a 04 LLY 2wd 3500 ext. cab with 25,000 miles on it. I have complained about the fuel mileage from day one. My last trip to California from Missouri with 9000 pounds of trailer and load got me a best of 8 mpg and a worst of 5. On the return trip empty with no trailer I got a best of 15 and a worst of 13. Also on the trip out it overheated 3 times and could not run the speed limit up by Vail, CO. Dealer has not looked at it yet, he says it needs time to break in. I will have it there Moday morning, I am just looking for some suggestions on what might be wrong. My 2001 with Juice on the same trip will get 9 - 10 loaded and 18 - 19 unloaded and its a 4wd.

[Darip]

Are you running a grill insert of some kind? If so, take it out and try your pickup. My LLY was running the fan all of the time while I was towing and then I took out the Billet Grill insert and it seems to work fine. Just a idea.

[More Power]

Do you have an EGT & boost pressure gauge?

These gauges can help troubleshoot a restricted air supply system, clogged exhaust system, as well as help find what a particular powertrain likes, as far as engine rpm and vehicle speed.

Do you have a non-stock tire size?

What speeds are you running?

Do you have any accessories installed that could affect engine temp, wind resistance or vehicle loads?

I once heard from a 6.5 owner who complained about the poor fuel economy he was getting with his K3500. Turned out he had a 3000-lb welder more or less permanently mounted on back and drove 85-mph on the interstates.

MP

[rickdlance]

I have 2 2001 Dmax,s and this one gets 25% less mpg on the same excact trip. The truck is only 6 weeks old and has no mods whatsoever.

[More Power]

There is a delicate balance between all of the engine sensors and powertrain control. If a sensor is out of spec, but not enough to set a code, it could produce a slightly incorrect input to the ECM, which could result in low power or lower fuel economy.

The fuel-rail pressure sensor, MAF sensor, engine temp sensor and other analog type sensors would be high on my list for testing.

This is one reason why a boost pressure and EGT gauges are useful. They can help a driver determine whether the fuel/boost are more or less correct for a given situation.

MP

[mark45678]

rick I think you dealer need to look at your truck! my lly allison 4x4 2500 gets 16+ mpg at 80 mph..... 12+ loaded (enclosed car trailer 7500lbs) at 75!.....FYI JUICE will help out and its comming soon,real soon! ;) as for the over heating the HOTEST i had mine is 205*f up hill 7500 in tow (temps rock solid not climbing)

[Mile Hi Guy]

I feel your pain.

Mileage is similar and power seems so so!

I mentioned similar Concerns to a VP at the dealership who has the exact same truck only with the LB7 and he said that they noticed no appreciable gain in performance so far with the LLY. :(

I also note that my cooling fan comes on frequently on 85 degree days with no load. Gauge shows a consistent 210 however.

Also, may be it

[rickdlance]

I have contacted GM about this and they say they do not have a fix for it yet. They are working on it. I expect I will get a new truck. I just hope it doesn't have the same problems.

[rickdlance]

GM called today and told me since this was not a safety issue that I would have to wait till they found a solution, at a cost of about $200 a week extra in fuel. I am going to the Dodge and Ford dealers tommorow and expect to be GM less. I can not believe the way they treat someone that owns 3 of there trucks.

[Stephen1]

Hire a lawyer. In most states spending about $500 to $1000 with a lemon law lawyer will get GM to purchase the truck back from you at a good price (moderate deduction for actual mileage) plus your attorney's fees. Much better deal than trading in. Work the GM customer service and see what they will do. Then call the lawyer. If they admit that there is a problem and they cannot fix it they almost leave you with no other alternatives.

Check out the details on lemon law in your state. Usually if you cannot fix the same problem in 3 visits to the dealer you have a good case.

Steve

[northofthe52nd]

I got my first diesel(2500 HD D/A cc) 2 yrs.ago and my first camper (32' 5th wheel). Pulling the loaded camper (14,000#) to Canada and back to TN I averaged 14 mpg. Sections through WV went down to 12. Empty local I get 18 and highway 20.
Only problem so far was injector replacement.
From what I have just read, I am blessed.

[rickdlance]

The guy's at Molle Chevrolet are working harder than GM at trying to fix my problems. Randy is going to try changing 3 of the injectors as soon as he can get them in. Meanwhile we bought a 2003 Duramax today from Marty @ Molle. Expect to have better luck with it.

[rickdlance]

Just a little update on my dismal 2004 experiance. Randy at Molle has tried everything except new injectors. We are waiting on those now. In the mean time I bought a 2003 dmax/allison used from Marty also at Molle in Blue Springs, Missouri. These guys are working their a@#s's off trying to help. I have had such good luck with my 2 2001's I could not stand to switch to dodge yet. As far as the 04 goes I have filed a lemon law claim with the BBB. I hope GM finally corrects their problem. Anybody got a 2002 drw ext cab for sale?? I think that was the best year.