Dramatic loss in power/MPG

[rwfan99]

I took my 08 VUE XE (4cyl.) Into the dealership because I've noticed dramatic power loss and loss in fuel economy (4-5mpg decrease). Dealership said no codes came up and in their opinion, when test driving my VUE and a new one on the lot, didn't "feel" a problem. I drive my VUE 100 miles daily and so I know when it's not driving correctly. Wondering what could be the problem. I've also noticed the engine sounds like it is revving up too much and you can hear under the rear seats (muffler or cat. conv. perphaps?). It also seems sluggish and hesitates when accelerating. On the highway, it's constantly dropping into 3rd to stay at 75MPH with or without cruise on. Anyway, any insight or advice is helpful.

I mentioned to the dealership two things that happened recently that I could think might have caused this.

1. I ran it out of gas (yes, I should have known better)
2. I just replaced the tires (one size taller than OEM)

Dealership said my gear ratio, and ECU are going to respond different with the new tire size and perhaps causing what I'm noticing, but I find it hard to believe my MPG and power would be decreased that much. Also, I was informed that the VUE does not have a fuel filter, since I had asked if that was clogged due to running it empty.

I noticed this happening after having the oil/air/tires changed both within a day of each other.

I am at a loss. This post is all over the place but I'm getting really annoyed that my VUE is acting this way, and is proving to be somewhat dangerous on the Interstate with no power.

[twosaturns]

you need to do the math on how much % bigger your tires are now. the MPH and MPG will both show lower than actual. you effectively raised your final drive ratio which would also cause it to downshift where it didn't used to.
another contributing factor could be a switch to winter fuel, which, foe me, drops economy 2-3 mpgs.
do a search on 'miata tire calculator' where you could plug in your sizes and it'll give you a % difference.

[Speakrz]

Try this site for your tire calcs, it will tell you what your speed has changed to w/ the larger diameter tires size. powerdog.com/tiresize.cgi

You might want to get you exhaust system checked - maybe you have defective cats, resonator or muffler... the dealer should be able to help you with that or take it to a good muffler shop close to your location.

[Mic__]

Originally Posted by rwfan99

I took my 08 VUE XE (4cyl.) Into the dealership because I've noticed dramatic power loss and loss in fuel economy (4-5mpg decrease). Dealership said no codes came up and in their opinion, when test driving my VUE and a new one on the lot, didn't "feel" a problem. I drive my VUE 100 miles daily and so I know when it's not driving correctly. Wondering what could be the problem. I've also noticed the engine sounds like it is revving up too much and you can hear under the rear seats (muffler or cat. conv. perphaps?). It also seems sluggish and hesitates when accelerating. On the highway, it's constantly dropping into 3rd to stay at 75MPH with or without cruise on. Anyway, any insight or advice is helpful.

I mentioned to the dealership two things that happened recently that I could think might have caused this.

1. I ran it out of gas (yes, I should have known better)
2. I just replaced the tires (one size taller than OEM)

Dealership said my gear ratio, and ECU are going to respond different with the new tire size and perhaps causing what I'm noticing, but I find it hard to believe my MPG and power would be decreased that much. Also, I was informed that the VUE does not have a fuel filter, since I had asked if that was clogged due to running it empty.

I noticed this happening after having the oil/air/tires changed both within a day of each other.

I am at a loss. This post is all over the place but I'm getting really annoyed that my VUE is acting this way, and is proving to be somewhat dangerous on the Interstate with no power.

HOw's is your air filter....those are natorious to kill mileage as they clog.


Also, you mpg figures need to be adjusted by the % change of tire rolling distance (i.e circumfirance)


.

[rwfan99]

Thanks for the info guys. I will do my research on the tire size affecting performance. It was expected when I decided to change the tire diameter, I wasn't expecting the hesitation I was experiencing. That said, I took it to the dealer this morning and had them flush the injectors/fuel system. Driving back to work it was like night and day, I have immediately noticed a difference and feels like it used to. The true test will be this afternoon when I go home.

[ski2moro]

never mind