I have a 2009 1500 trx4 and lately I have noticed that I am getting about 7.5mpg. I took it to the dealership where they say they cleaned the throttle body. That did nothing. I am very concerned that there may be a bigger issue that I am not catching. The fuel saver sensor comes on and off and chuggs a bit around 30 mph. I have explained all of this to the dealership and they find nothing wrong with it. Does anyone have any ideas?

 

Tune up? Change plugs? Fuel filter? injectors?

Lots of things it could be. Any trouble lights on the dash?

 

Since he said the Dealer looked at it and found nothing wrong, I would certainly hope there are no lights On in the dash.
Fuel inhectors will send a code if something is wrong. An activer DTC code that the dealer would have picked up on. I'm sure a Tech had done some live data watching while at idle and while going through the rpms. A bad injector would have shown on the graph.
Spark plugs and bad or cheap gas will cause a vehicle to not throw codes and get bad mileage. A heavy foot will not help the situation.

It would help if you gave a few more details about your truck...
Lift? Tire size? Type of tire? Maintenance history? Octane used? Highway driving or city driving?
How are you calculating the gas mileage? Overhead isnt as accurate as doing by hand.
It's VERY COLD out this time of year, do you warm up your truck before getting in it? That will drastically reduce gas mileage as well!!!
I get 18/19mpg in my car consistently. During this winter so far I have been getting 15/16mpg because I warm it up with my car starter everytime I get into it. You can't account for the warm ups or when our truck is idling so it skews your true MPG readings. So, you may be getting 13mpg, but because you warm it up it seems like your getting alot less.

 

Don't forget that if you live in a section of the USA that has "winter mix" gasoline, you will yield a lot fewer MPG with this gas.

Andy

 

Cold will do it, but that is even low for the cold. I lost 1 on top of what I lost already just going from 30s to 10ish. Overall I am down a little over 2mpg over summer.

 

I have had this happen in the past with other vehicles. Have them check the O2 sensor. When they go bad they can do that. I have had 2 cars do this and never throw a code.

 

I believe that truck has 4 02 sensors. If its running rich or one is bad it will throw a check light. If that truck runs rich it will set a light. The systems are very sensitive to anything out of parameters.

 

HA! Cold!...*scoffs and looks at his temp dial*

I agree with the whole winter fuel thing. When I had my hemi, I saw at times a 4 MPG drop just in winter, and it was very quick so I new when I had just put winter fuel in.
We had an issue with a plan up north having a bad fuel mix, they sent out fuel with a bad ratio. All we had to do was go to another station, and it fixed itself. Try fueling at another station too...

I could potentially say that it could be an 02 sensor too. I know a user posted here about a truck throwing a code, but I know there is a certain range it will go without throwing it. You would not want all those sensors throwing codes for the couple seconds that the hemi might burn improperly.

It very well could be that he is around the limit of those sensors, and the combination of winter fuel, with a possibility of poorly mixed fuel is not helping.

 

Winter fuel isnt going to frop mileage that much fellas. The winter blend has about 2% less energy than Summer blend. This doesn't reduce gas consumption as much as you'd think but it does reduce it though. I would say .5-1mpg is about what you can expect.
Also, Ethanol blends reduce gas but again, not as much as you'd think. 10% Ethanol, something that NY actually uses all year round now burns something like 30% quicker. So, with a 10% blend and 30% quicker burn equates to a 3% loss roughly.
13mpg X .03=0.30mpg loss due to ethanol blend. I would say .5mpg loss is about what you can expect as a loss from an ethanol blend of fuel.
Combining the two, 1-1.5mpg reduction would be a reasonable figure. The rest of the loss is from evaporation and idling to keep your vehicle warm!

 

I live in South Dakota, where it does get damn cold, but I try to only warm it up for a few minutes. Mostly garaged. I do mostly city driving, but during the summer, I was get 13 mpg. I don't have a heavy foot, I drive pretty cautiously as I don't want to screw up my truck. I bought it in July so I am just hoping nothing majorly wrong. There are no codes on the dash and I have been calculating mpg by how much I use to fill up versus the mileage on the od.