Originally Posted by grosamond
I have a 2007 250 6.0 with a 5 inch turbo back exhaust with an Air Raid intake. Immediately after the install of the exhaust the MPG went up to over 18 MPG. After putting the pedal to the metal on one occasion, I noticed a clanking sound that seems to come from the Turbo. All of a sudden the MPG dropped dramatically. I pulled a 16' trailer with 100 bales of hay and got 12 MPG when previously I got 16+MPG. There is no check engine light and all the gauges are normal. I have hestitated on adding a downloader to the truck until I can find the 'root cause' for the current problem. Does anyone have an idea of what happened and the potential fix?
First question, are you hand calculating your mileage or going by the lie-o-meter if your truck has one equipped for your mileage calculations. The only way to really accurately figure mileage on a diesel is to literally fill it up to the top of the tube and check that way. Each tank will "foam" up differently causing some fluctuation in how much fuel you're actually getting in there. 12 mpg pulling a 16' trailer with 100 bales of hay, that's gotta be in the neighborhood of 7-9k trailer weight, I'd say 12 isn't too bad considering your trucks not even broke in yet. I honestly don't know how you got 16mpg pulling it before. As for the "clunking" sound I'd need a more descriptive explanation of the sound. If you bought a turbo back system it could be your downpipe rubbing on the firewall under a hard acceleration when the motor torques, but that's a vibration. Then there is the old "turbo fart" which is also a rubbing sound when the VGT turbo on a 6.0L has nothing to do with the extra boost it "farts" it back out the intake. If its a metal on metal sound I'd check out your down pipe and make sure its properly secured to your turbo, if it was at all loose you'd notice problems right away. Hope this helps.