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Mods and MPGs

4K views 18 replies 15 participants last post by  ORT 
#1 ·
Hi, I'm new to the site and was hoping that maybe someone could give me some opinions and insight.

I purchased a 2008 Ram 1500 SLT 4x4 Hemi Quad cab, and it came with a few light mods. It has K&N Cold Air Intake, Throttle Body Spacer, Gibson Exhaust mainfolds along with full Gibson dual Exhaust.

I seem to be getting pretty crappy gas mileage, meaning worse then my '05 Hemi I had. I usually get 13 MPG on the highway and less then that around town. I usually do not get anymore then 300 miles to the tank.
My question is, how much is the aftermarket stuff mentioned hurting my MPG? I thought it would actually help it, but it doesn't. Would taking the throttle body spacer off help? That would be the easiest for me to do. Would that effect the computer and the rest of the setup? I'm really disappointed because I thought the '08 would be better and now I regret getting rid of the '05. I'm to the point where I want to get rid of it and get a Ram Diesel, and I have only had it 6 months.

Any thoughts or ideas?! Please help! Thanks!:smiley_thumbs_up:
 
#2 ·
Def ditch the throttle body spacer. The Gibson stuff def should not be hurting MPG at all!

Do you know when the last time the engine was gone through for a "tune up". Bad spark plugs can create bad MPG.I would not be happy with 13 mpg on the highway. At 70 mph my dads 07 gets 17.5+ mpg. There is def something not right.


Stock wheels and tires? 2wd/x4? Has it been tuned?
 
#3 ·
I do not know when then last time it had a tune up. I bought it in October 2011 with 36K on it...now it has 48k on it. It is a 4x4 with stock 20" wheel and tires. I would be estactic if I got 17.5mpg!!!! I have to figure it out...cause it is really killing me.
 
#4 ·
How much do you like playing the tune that the gibson plays? How fast are you averaging on these trips? Thats a direct line to lower MPGs. Start out with tire pressure, get up to spec and maybe even 5-7lbs over. Check your plugs, or just replace them if you dont know when they've been replaced. Hows the bed, is it loaded? Remove any unnecessary weight.
 
#7 ·
Welcome! Sorry to hear about your issue. I think you should definitely take your TB spacer out, as they usually don't help anyways. Bone stock I got 18 highway with my '06 Hemi QC, something is not right for sure. Start with the basics.... plugs, filters, tire pressures. If this doesn't help, keep in mind that other things such as bad wheel alignment, dragging brakes, even worn u joints can affect fuel mileage, basically anything that causes more than normal drag on the drivetrain. I replaced my worn transmission in my '01 5.9 QC , my fuel mileage immediately went up from 10 MPG avg, to 13+! Probably not your issue, but just saying. Good luck!
 
#8 ·
Thanks for all the advice. Sorry it took me so long to respond. Well I took the TB spacer out over the weekend..take about quieter! The loud whistle and air sucking is gone. I just filled the tank this morning on my way to work, I reset the MPG on the console computer. When I got to work, which is only about 35-40 miles from where I filled it, the computer said 19.5!! of course I know it always starts really high and eventually drops down but I definitely think taking out the TB spacer helped. I drove with the cruise on the whole way about 72mph. I'm very curious to do the hand calculations at the end of the tank, and after normal driving.
 
#9 ·
I see you're in nepa, I would drive with the cruise on up there with all the hills and mountains. You can do a better job of accelerating up those grades with your foot. I just bought a house in Cochecton across rte 652 in NY.
 
#12 ·
Its been a while since I have been on here, sorry about that. So here is an update. I took the TB spacer out and it didn't seem to helped out too much with the MPG. It seems that I have an exhaust leak on the passenger side between the block and the Gibson manifold. I know that would probably hurt the gas mileage but I can't imagine it would make it that bad! I don't know where to get it fixed and I don't know if I want to tackle that myself...I can't even see some of he header bolts, let alone get to them. I'm thinking putting on double exhaust manifold gasket would fixed the problem.

Also, the MDS in my opinion seems to be working a little premature. I seems like it is ALWAYS engaged and very sluggish. Going up hills...I have to press the pedal down pass halfway just to get the truck to go. Something is really wrong with the truck and i'm not sure what to do.

What kinds of plugs are in the truck from the factory? What do I put in?

PLEASE HELP!!! Thanks :)
 
#15 ·
I know what you mean about having to push the pedal down to go up a hill but also the throttle response on our trucks is not the greatest which is the problem you are havin with that. For sure tune it up and check your throttle body (dont know if you did when taking the spacer out) but when i looked at mine when i bought it at 40,000 miles its was filthy and that gave me alittle bit more pep.

I am getting a diablosport intune to adjust my throttle and get a few more ponies
 
#16 ·
My 07 got about 16.5 on my last highway trip running between 70 and 80 mph. I have the 3.92 gears. As far as mods I have the Diablosport Intune with the 87 octane tune installed, Vararam hemi under glass intake, and a fastman ported throttle body. Keeping my foot out of it is the hardest part. I run it upto 120+ mph on one stretch just to see where it topped out at. I let off once I saw I went past 120 and it was still going. Also even before my mods my mds never seemed to kick in very much. Usually when going downhill or very very level surface. It would kick out at the slightest of inclines. I have never had to go half throttle to kick it out to make a hill.
 
#19 ·
What do you have your top speed limiter set at? 120mph is fast in one of these trucks on the highway.
 
#18 ·
My 08 TRX with MDS is bone stock and I get almost 18 hwy. 15.5 on regular tanks and that includes the 30 mile idle home in stop and go traffic.

+1 on the tire pressure. I always keep mine jacked up a bit.

E85 guy. If it isn't a FlexFuel vehicle, no. Do you have a FlexFuel badge on ur tailgate?
 
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