07 Merc Mountaineer trans/gearing problem

[skot748]

I have a 2007 Mountaineer V8 AWD Premier w/ 28K. I think there is a gearing problem. I really have to mash the gas to get it to accelerate at a reasonable rate (like keep up with normal traffic). I also don't get the kind of gas mileage that most of the posters on this site seem to be getting, I pretty much avg 13 mpg no matter what. Maybe on the freeway it goes up to 15 (at best). I bought it new in '09 (it had 119 miles on it from the dealership). It is a good looking SUV and I like all the features, but the gas mileage is killing me. I had a '02 5.9L Durango before this and the mpg was about the same. I am very disappointed on how this SUV drive, especially after reading all the praise it gets. Any help would be appreciated. Thanks

 

[Alan Lloys]

I have a 2007 Mountaineer V8 AWD Premier w/ 28K. I think there is a gearing problem. I really have to mash the gas to get it to accelerate at a reasonable rate (like keep up with normal traffic). I also don't get the kind of gas mileage that most of the posters on this site seem to be getting, I pretty much avg 13 mpg no matter what. Maybe on the freeway it goes up to 15 (at best). I bought it new in '09 (it had 119 miles on it from the dealership). It is a good looking SUV and I like all the features, but the gas mileage is killing me. I had a '02 5.9L Durango before this and the mpg was about the same. I am very disappointed on how this SUV drive, especially after reading all the praise it gets. Any help would be appreciated. Thanks

Sorry to hear about your problems on it. I have the 2008 model with V8 AWD and find that it has no problems keeping up. It is however quite easy to accelerate faster than you think which makes the gas milage go down.

In mostly city driving in the winter I get 14.5 MPG on average. If I reset the MPG while cruising on the highway at 70 MPH I will get between 18 and 20.
Try and do the same in yours. If you are seeing 13 GPM on the highway as instantanous MPG there is something wrong.
You should be getting a check engine light if you have a cylinder not firing or anything like that. You may want to check your RPM's when cruising on highway also. It is possible that your torque converter is not locking up properly.
Finally check that you are not in AWD lock (4x4 light on instrument cluster lit).

If the vehicle was really sold as new it should be under warranty and you should work with the dealer. Even if it was sold as used (because of the 117 miles) the 5 year/ 60 miles powertrain warranty should still be in effect.

All that being said the gas milage really depends a lot on driving style. I talked to an owner of an identical vehicle to ours and he was getting 11 MPG. Mostly driving in town. It is possible to do this if you constantly accelerate hard out of the lights and brake late instead of coasting to the red lights. There was nothing wrong with his vehicle - only with his driving :scratch:

 

[skot748]

Thanks for the quick response. I don't think I am accelerating too fast. I can and the Merc will accelerate quickly if I want to, but I try to accelerate at a fairly modest pace just to try to save gas. There is no check engine light and the 4X4 (squiggly lines) light is not on either. I'll try to see what happens on the highway and see what it looks like. I think I will also take it in and have it looked at. I have taken it in to the dealer for other thing where they had to drive it and they said nothing. I will take it specifically for this issue and post the results. Thanks

 

[waskly]

did the mpg recently go down? like starting November?

since gas stations started using winter blends. also is it 10%e gas or 100% gas, normally in the winter, you will see a 1-2 mpg decrease due to winter blends in fuel.

 

[skot748]

No, it actually never changes. 12.7-13.3 avg. My wife got about 15-16 on a long drive from Virginia Beach to Pensacola. It pretty much stays at 13 no matter time of year or how I try to drive it.

 

[waskly]

just for kicks i rememeber 07 v8 had a reflash for various problems one was for inaccurate message center avg fuel economy.

i would see if the local dealer since its a dealer tool, has a newer calibration and take it from there. if your in warrenty, 3/36 this should be free.

it should reflash pcm/tcm.

some other symptoms are

cold hesitation/surge
long crank
high idle during warm up
lower then desired rpm during long deceleration.