I have a 2007 Dodge 1500 4x4 Hemi. I have become quite in tune with how it runs and with making use of the MDS. I noticed yesterday that while at low speed rpm, without MDS activated, the sound surges like the rpm is going up and down ever so slightly. For example if Im crawling along at about 30mph with accelerator held at one position. I then noticed that when MDS kicked in the exhaust sound was louder than normally is with MDS active. My gas mileage also dropped slightly. I know the overhead display is not completely accurate but it is good enough to notice a drop. I have been maintaining 17.9 mpg average city/hwy and yesterday I could not maintain 17. I know its not much of a drop but with me noticing the difference in running and the drop it tells me something is off. What do I need to check or have checked ? There is no warning or service lights on. I am going into town to the dodge dealer today so if I can have some idea of what to have them focus on that would help. They rely heavily on the test modules you hook up but I have read that there are several things that will not throw a code if they are subtle. Thanks for any help

 

I wish i had 17mpg! Im luck if i get 11! Check your plugs. Im sure thats what my problem is.

 

i had same problem, could not hold tach at 1300 rpm would surge up to 1600 down to1000, if i bliped the gas at 30 mph tach would drop to 400 and pop up to 1000, gas mileage tanked, and than set a p0404 code changed the egr valve and all is well, good luck

 

Hey guys i had the same problem but I fixed it first what you need to do is treat you fuel tank with a product called sea way you can get it at auto value auto parts store there is two types of this stuff the liquid form and spray form the spray is for you intake but ask for proper instructions how to use the stuff and a possible why the surging is you're EGR could be bad now they only I think I paid for mine was $85 Canadian

 

Oh I forgot to say you need to treat your fuel tank two time a year my dodge dealer ship never told me that the vent is in the tank and it vents out through the engine and I can and will plug if not treated with this sea way product and from what im told its the best on the market