Hi all. So, long story short, I thew on some 35" mud tires about a year ago, which opened up a huge can of worms (other mods related to having 35" mud tires), but it also destroyed my otherwise reasonable fuel economy. I didn't buy a truck for fuel economy, but my 2008 Ram 1500 with 5.7L hemi, without the lunker tires, used to get me around 18-19 on the freeway, 14-15 in the city, which I was very happy with. With the newly added weight on my axles from my 35s, along with the relatively heavy milled 1" spacers I had to run them with because of the backspacing of my wheels, my fuel economy dropped down to around 13.5-14.5 highway, and 11-12 in the city.
To take a shot at grabbing back a few MPGs, and to make my truck cooler (let's get real, that's what I'm after), I decided to throw $1k into her recently and put in a Volant CAI, Flowmaster 40 (which I acknowledge does not improve economy) and a Superchips Flashpaq tuner.
Now to my question to y'all. That tuner I bought came with a towing tune, performance 91 octane tune, 87 octane tune, and an "economy" tune. I'm running the "87 octane" tune on that tuner because I read dozens of reviews that said the performance tunes (the 87 or the 91) get the best economy, and that the "economy" tune does NOT. That confused me, but the reviews were so consistent with this opinion, and I even confirmed that with the Superchips technicians who agreed, that I decided to run the 87 tune first (and I run regular 87 octane gas).
I'm through two full tanks of gas, and the results have been bizzare. At first, I'd be on a 50mph road and it would start getting around 16-18, even with stop lights. I was thrilled. Then, if I parked just once and turned the truck back on and drove in an area with 30-45 mph and more stops, boom, it tanked down to around 10-11, and sometimes it reads 7mpg! I'm using the on board computer computation, which I acknowledge isn't always accurate, but, I have previously hand calculated my economy and my computer happened to be very close to the same numbers. Anyways, I'm wondering what you all think. I'm averaging out to around 13, which I think is about 1-2 mpg better. Not sure if that's more from the CAI or the tune.
In any event, I'd just like anybody's opinion as to whether I'd be better off running that economy tune. When I reset my fuel economy computer in the city, it immediately starts reading it at around 5-9 mpg, which NEVER happened before when I reset it in the city. Sometimes, however, I'll reset it and it will mark around 16-18 mpg on faster city roads (1 mile traffic light intervals at 50mph). The on board fuel economy computer seems to be confused. The tune, however, did make my truck run smoother with gear changes and acceleration, however I'd still like to know whether I'd be better off with the economy tune in order to achieve the best fuel economy.
Any opinions? Should I run any other tunes? Economy tune? Pay extra gas $ to run 91 tune with 91 octane gas? Any advice would be greatly appreciated! I just want my tuner to give me the best fuel economy results : )
Thanks in advance, and I'd be happy to answer questions about my experience and observations with any of these mods, or other mods in my profile.