I have a 07 LBZ on trip to FLA for bike week I pulled a 14-ft vnose trailer running around 65-70 mph I only got 11-miles to the gallon And the engine lite came on. Stop at chevy they said it was the egr motor they replace it no change in milage and the lite back on going back to chevy

I am going through something very similar... went to bikeweek and got 7 mpg pulling a toy hauler. EGR light came on, we blocked the tube, I bought EFILive from Nick (duramaxtuner.com) and Floriduramax1 helped me tremendously, he turned the EGR off, so check engine light is off.

But on the way home I'm only seeing 10.1 mpg until we hit winter blended fuel, then it was 8.8.

Still trying to figure out why my mpg is so low.

A month a ago I pulled a 20 flat bed from dallas to SLC. 7.7 mpg at best. I was loaded less than 2000 lbs and on the way home i was empty. Around Whichita Falls, Texas on the way home, something changed.. The truck started to run free and my milage came up. Around town my milage accually came upto 21 mpg. The best i had ever done before is 14. I just took the truck to Coolidge AZ. This time with a 6 horse trailer. From Dallas to west Texas I was getting 11.3 mpg. I thought great...A little too soon.... Check engine light came on and the truck had just enough power to get off the road. I could not pull any codes with my code reader, but i did reset the computer. I fought the truck like this until Demming NM. My milage went to the toilet. 8 mpg and down. In NM the dealer said "you have a bad fuel filter" The filter only had 5,000 miles at best and i am running off a 100 gallon tank. I had not bought bad fuel.. I have been able to pull one code during all of this. A LOW FUEL RAIL PRESSURE. I am still having trouble and no one knows what is wrong. My tail pipe is wet with fuel. My Milage sucks.. Are there any real mechanics out there any more or does every one rely on a computer to say what is wrong and how to fix it.. :eek:

The dealer says it is my afe air filter setting off the code

i know if you put too much oil on the filter it can trip a code

How about the EGR

AFE said not enough back pressure need to put the cat back on