Hey guys/gals...

I just purchased a 2008 dakota v8 4x4 with 110k on it and it seems to run fine - idles around 500 rpm when warm but sucks on gas. I am getting about 10-11 mpg average city/highway - i prob do a 50/50 split. I did reset the ecu by disconnecting the battery and the mpg shot up to around 15-16mpg range for about 100 miles then dropped back down. I dont want to start randomly replacing parts and hoping anyone has a way to diagnose it. There is no check engine light or anything but would imagine a sensor or something is starting to go bad. I did do a full tune-up - all 16 plugs and wires, pcv valve, new k&n cold air intake. No real change in mpg.

I do have a actron autoscanner that i can get ecu readings while it is running but i dont know what all the stats mean. Hoping someone can help.

Thanks

 

Stock tire size? Any modifications?

 

How far are your average trips?

 

Hey - tire sizes are stock tires and wheel 16"


The normal trips to work and gym are 3-5 miles some stop and go and some highway for a few exits.

 

Short trips/stop and go driving kills mileage.

 

ya but I would think it would be more around factory specs of 15/18 - more towards 15 at the low end and maybe 13-14 if I really gun it light to light. Reason I say that is I have car as well and that gets its factory mpg doing the same trips.


Also I am thinking the poor gas mileage equates to something not working 100% - and looking to solve it and get it running like a top.

 

Are you just using the computer display on the headliner?


Do the calcs for a few tanks full, and then decide if there is really something going on.

 

3-5 mile average trips means your truck is spending probably half to most of its time still in the warmup cycle on every trip, when extra fuel is injected to get it up to operating temperature quickly.

And if the warmup cycle of your V8 is anything like that of my V6, it takes longer than most cars I've seen, especially those cars with electronic-controlled fans that don't engage until warmup is complete.

To give you an idea of my own experience and how it probably relates to yours, my commute to my job was 8 miles all-city each way and I was averaging 14.6 mpg (hand-calculated). After moving much closer (2.5 miles all-city each way) and changing nothing else, it dropped down to about 12 mpg average...because it was now spending almost the entire commute in the warmup cycle.

Put side-by-side, your 10-11 mpg with a HO 4.7L on short trips and my 12 mpg with a 3.7L on short trips is probably nominal.

 

ok, cool thanks for the comparison. I didn't know it dumps that much fuel for the warm-up. And was more concerned with something not being right then fuel economy. I actually have a superchips programmer to setup for the increased hp/tq but didn't want to if the truck wasn't 100%....


Yes, I have been figuring out the mpg by hand but the overhead has been somewhat in the same range - give or take roughly 1mpg.

 

I have about 8.5 miles to work and average 13.5to 14.6 miles per gallon . My last job was 26 miles each way and i averaged 16.5 miles per gallon even going from sea level to 2500 foot elevation on my way home. truck has 211xxx miles on it 05 Quadcab 4.7 4x2. I think yours is normal. Cai wont improve your MPG.Maybe bet a tune should help if you can keep your foot out of it.