2005 Equinox - sudden MPG loss

[Bgallagher]

Originally Posted By: 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?


I try to avoid the stealership at all costs. My transmission still agressively upshifts and I like it that way

 

[JamesBond]

You mentioned that you were working under the hood before this started, did you leave a vacuum hose disconnected, clamp loose or sensor unplugged? I've done it, and it doesn't always cause a check engine light.

 

[buster]

I just got 24 mpg on this last tank in the Honda. Drove really conservatively too.

 

[bourne]

to anyone who thinks their O2 sensors are reacting slow/going lazy, I suggest spending $25 first and ordering this : http://www.amazon.com/BAFX-Products-Blue...s=bluetooth+obd

This will tell you whether your O2 is switching between lean/rich mix, when it goes into open/close loop and also has a diagnostic test while you drive. Just get the tool, and download Torque for your Android phone/laptop etc.

 

[Bgallagher]

Originally Posted By: JamesBond
You mentioned that you were working under the hood before this started, did you leave a vacuum hose disconnected, clamp loose or sensor unplugged? I've done it, and it doesn't always cause a check engine light.


I just went out during my lunch break and checked for just that. Nothing loose or disconnected. Everything is tight.

 

[Vikas]

Does Torque run on your laptop?

 

[Astro14]

Some very good suggestions - with colder weather, you also have to consider a faulty thermostat (running too cold to get to closed-loop) as well as coolant temp sensor (also keeping the car in open loop). Open loop operation often results in more power because it is richer (erring on the side of caution).

 

[ls1mike]

I couldn't tell you what MPG I get in my Equinox. Never paid a attention, but at 99,000 with a 3.4 it is time for a tune up.
Plugs, wires, air filter and 02 sensors.

 

[raffy]

It could be your thermostat - what is your coolant temp gauge running at? On most GM cars it should run 3/8 to 1/2 on the gauge most of the time after the car is warmed up. If it's only running 1/4 of the way or less after about 20 minutes or so of driving, the 'stat is not working right. I had this problem on our '05 Grand Prix, didn't know I had it until the weather turned cold. It never really warmed up and it got so bad that the CEL went on with a code saying that the coolant was not getting warm enough after a certain length of time. Also, the heater was not working well. Replacing the thermostat (and also the coolant itself as it seemed to be due) fixed that problem. I have noticed a considerable increase in gas mileage as well (can't quantify it yet but a definite increase).

Do you have good heat in the car? If not, the thermostat could be your problem.

 

[DriveHard]

My mileage dropped from between 17 to 18 mpg on my truck to being in the 11's the last two tanks. Our highs in the single digits is probably mostly to blame.

 

[Bgallagher]

Originally Posted By: raffy
It could be your thermostat - what is your coolant temp gauge running at? On most GM cars it should run 3/8 to 1/2 on the gauge most of the time after the car is warmed up. If it's only running 1/4 of the way or less after about 20 minutes or so of driving, the 'stat is not working right. I had this problem on our '05 Grand Prix, didn't know I had it until the weather turned cold. It never really warmed up and it got so bad that the CEL went on with a code saying that the coolant was not getting warm enough after a certain length of time. Also, the heater was not working well. Replacing the thermostat (and also the coolant itself as it seemed to be due) fixed that problem. I have noticed a considerable increase in gas mileage as well (can't quantify it yet but a definite increase).

Do you have good heat in the car? If not, the thermostat could be your problem.


Last year I replaced the thermostat and coolant temp sensor then flushed out the coolant. The heat is great in my car. it falls between 3/8 and 1/2 and never above it.

I should be getting new plugs delivered this weekend and will be replacing them (AC Iridiums for the same.) if that doesnt work then I will replace the O2s

 

[NHHEMI]

I see you recently replaced the air filter. Is it a regualr paper one or did you go with an oiled filter like a K&N? If it is an oiled filter you have probably got a fouled MAF. Ditch the oiled filter, clean the MAF( be very careful - use a MAF specific aerosol cleaner and do NOT touch the MAF screen - spray it only ), and put a regular paper filter/dry performance type filter back in. If a paper filter was used disregard. Only thing different I can come up with from what the others have already said.

I had a 2008 Equinox and even towing I didn't see those MPG #'s. That is pretty bad. Have you been letting it sit and warm up for extended periods of time during the recent extreme cold across most of the country or something?

 

[citationxeleven]

Did you fill up at a different gas station, or maybe try a different station next fillup.