2005 Equinox - sudden MPG loss

[Bgallagher]

Hey everybody. For the past few weeks I noticed a sudden drop in my MPGs, going from around 20mpg to around 13-14. I know with the cold weather that the MPG does go down some but I thought that is a rather drastic drop. I changed the oil last month and also replaced the air filter / PCV valve. No sudden fluid drops and my tire pressure it where it should be. I figured I would take out the blugs and take a look at them but I figure why not ask BITOGers to see if they have any ideas themselves.

Thanks in advance!

 

[sasha]

at 99k you are due for a tune-up. plus try premium fuel. the 87octane winter blend fuel is [censored] imho.

 

[NateDN10]

A sudden MPG loss can be hard to diagnose in the absence of other symptoms.

My usual decrease in the winter is about 15%. It will be much worse if you do a lot of short drives - MPG is the worst while the engine is cold.

Winter gas does have lower energy content, but AFAIK, going to premium will only help make your wallet lighter.

So, is this decrease worse than in previous years? Unless you're way over the replacement interval for air filter & spark plugs, I wouldn't expect it to make much of a difference. No CEL, I assume?

 

[Bgallagher]

Originally Posted By: sasha
at 99k you are due for a tune-up. plus try premium fuel. the 87octane winter blend fuel is [censored] imho.


I changed the plugs out around 50k with iridums but they could be due for another change. I was considering the O2 sensors. No codes have been pulled yet but considering they are originals I figured they might be due for a change.

Nate - This is much more drastic then years past. I changed the oil/filter and air filter last month

 

[SwampSurvivor]

Wait and see what happens when the winter blend gas goes away.

My Focus goes from 36-38 commuting to and from work in the summer to 29-30 in the winter.

 

[buster]

I've noticed the same thing. I can't break 25 mpg in the 05 Accord, and that's driving conservatively. Mixed 50/50 Highway/city.

 

[buster]

Quote:
I was considering the O2 sensors. No codes have been pulled yet but considering they are originals I figured they might be due for a change.



Same here. I have the original o2, but I was told that part either works or it doesn't so I am leaving it alone.

 

[Barkleymut]

O 2 sensor would be my first guess, but it could be so many things that it is going to be tough to diagnose. That amount of a drop in MPG would lead me to believe there is something wrong. MAF, spark plugs, ignition system, fuel delivery.....

 

[[email protected]]

Yeah that winter gas & cold temps have me screwed up too... I went from 54mpg in the Prius during the summer time down to 45mpg now

lol

 

[buster]

Originally Posted By: [email protected]
Yeah that winter gas & cold temps have me screwed up too... I went from 54mpg in the Prius during the summer time down to 45mpg now

lol


This makes me feel a bit better. Seems we all lost about 10mpg LOL.

 

[The_Jake]

Originally Posted By: Bgallagher
Originally Posted By: sasha
at 99k you are due for a tune-up. plus try premium fuel. the 87octane winter blend fuel is [censored] imho.


I changed the plugs out around 50k with iridums but they could be due for another change. I was considering the O2 sensors. No codes have been pulled yet but considering they are originals I figured they might be due for a change.

Nate - This is much more drastic then years past. I changed the oil/filter and air filter last month


Clean your throttle body, MAF sensor, new air filter. Pull the EFI controller fuse for 1 minute and let it relearn. All cheap ways to improve MPG. Make sure your tires have not lost pressure due to lower temps.

 

[Bgallagher]

Originally Posted By: buster
Originally Posted By: [email protected]
Yeah that winter gas & cold temps have me screwed up too... I went from 54mpg in the Prius during the summer time down to 45mpg now

lol


This makes me feel a bit better. Seems we all lost about 10mpg LOL.


Misery loves company. I am going to check the plugs this weekend and probably replace the O2 sensors anyways instead of waiting for them to fail. This should improve it a little but I agree, might just be the winter mix and the cold!

 

[Danno]

Have you noticed a lack of power as well? If so, you may have a plugged catalytic convertor. This would be something that needs to be fixed asap and can't wait otherwise other significant damage will happen to your powertrain.

 

[Bgallagher]

Originally Posted By: Danno
Have you noticed a lack of power as well? If so, you may have a plugged catalytic convertor. This would be something that needs to be fixed asap and can't wait otherwise other significant damage will happen to your powertrain.


Good call! I have not noticed a lack of power though (luckily!) I have noticed an increase in power. Probably because of the cold weather creating a natural cold air intake.

 

[The_Jake]

Originally Posted By: Danno
Have you noticed a lack of power as well? If so, you may have a plugged catalytic convertor. This would be something that needs to be fixed asap and can't wait otherwise other significant damage will happen to your powertrain.


He would probably get a CEL if the cat is plugged.

 

[eljefino]

I'm going with a dragging brake. Drive uphill, toss it in neutral, coast to a stop, and see how effortlessly it reverses direction. Is this an AWD? I can imagine all parts of your driveline being stiff with coldness.

 

[Rand]

I wouldnt worry from 1 tank.
wait for a couple fillups.

 

[Bgallagher]

Originally Posted By: eljefino
I'm going with a dragging brake. Drive uphill, toss it in neutral, coast to a stop, and see how effortlessly it reverses direction. Is this an AWD? I can imagine all parts of your driveline being stiff with coldness.


I will have to try that when I get home tonight. Even if nothing happens it still sounds like fun

Originally Posted By: Rand
I wouldnt worry from 1 tank.
wait for a couple fillups.


It has been a couple fills. Averaging around 13-14MPGs. No changes in my commute or driving habits. 50/50 City Highway.

 

[stockrex]

check tier pressue, and check o2 sensor.

 

[eljefino]

Isn't this one of the vehicles that shipped from GM with really good MPG but then the dealers reflashed them because people didn't like how aggressively they (up) shifted?

Have you been to a GM dealer lately who could have surreptitiously done this?