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Discussion Starter #1 (Edited)
2010 Cobalt LT Coupe Automatic
80,000 km
Oil changed 2 days ago
Burning 85 pump gasoline
Spark Plugs changed about 7000km ago roughly
New Fuel Filter put in maybe 4000 km ago
Was put on a GM scanner and No codes in history
New Air filter and cabin air filter 2 days ago
average driving speed 30km/hr
Never driven hard always 10-15 below speed limit
easy on gas off traffic lights
Throttle Positioning Sensor reset back to factory
Catalytic Converter and exhaust system checked (all fine and to spec)
No fuel leaks
tryed a bottle of ACDelco fuel treatment plus from GM dealer
Fuel Guage SOMETIMES is jumping all over parked on flat no fuel moving in tank

Heres my problem.
Ive been in and out of stealerships for the past year with this car trying to figure this out.
My gas milage is insanely bad and it seems like its only me that sees this...
Im starting to feel crazy now to be honest

Ive posted this on here before last fall but cant seem to find the thread now.

What are somethings that can be causing me to have bad gas milage
Im from Canada so ......
my display right now is ready 11.3 km / 100 and steadily rising .3 - .4 every day

Here are somethings that stand out to me as abnormal
I get a fuel smell the first time I start the vehicle in the morning and only then
Maybe unrelated but I get a smell of windshield wash inside car with windows up after using (im at a loss here so Im putting everything i find weird)
Sometimes car seems a bit boggy during acceleration while the car is driving say like if i was to pull out and pass someone on the freeway or i want to go from 40 up to 50,60 ish

I will also ad that I did have a transmission replaced by GM about 20,000 km ago
I hit a rock and caused some internal damage to old transmission causing it not to go in reverse...long story short I went through insurance and had transmission replaced
 

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Winter gas, having an automatic, having a fuel leak which would explain the smell, had the pump recall done? Driving 10-15 under the speed limit actually wouldn't help, I want to say you get the best MPG at 45 MPH.

You're getting about 21 MPG which makes sense for many short drives, engine is most efficient when fully warmed up and uses more gas until fully warmed up. Mostly city driving and that's where it should be.
 

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Discussion Starter #4
Winter gas, having an automatic, having a fuel leak which would explain the smell, had the pump recall done? Driving 10-15 under the speed limit actually wouldn't help, I want to say you get the best MPG at 45 MPH.

You're getting about 21 MPG which makes sense for many short drives, engine is most efficient when fully warmed up and uses more gas until fully warmed up. Mostly city driving and that's where it should be.
Thanks for the reply
Its still warm temperatures here where I am.
Im not sure if I have a fuel leak becuase Ive checked around the car and no spots on the ground and Ive also started the card and reved the piss out of it for pressure and still nothing.I dont get a smell any other time..I think it may be me backing up into my exhaust..could be wrong but I have this feeling i dont have a leak..Im sure the million time Ive had this to the dealership they should of noticed something like that..I would think

Ive had the car checked for recalls and only ones that showed up were the power stearing and ignition..Is their a place online that I can check?

I dont always drive that slow..I was just trying to find a way to explain that Im not a speed demon on the roads.. I drive conservatively.

It is mostly short errand type kind of runs but man it cant be this bad.
Can it?
 

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Thanks for the reply
Its still warm temperatures here where I am.
Im not sure if I have a fuel leak becuase Ive checked around the car and no spots on the ground and Ive also started the card and reved the piss out of it for pressure and still nothing.I dont get a smell any other time..I think it may be me backing up into my exhaust..could be wrong but I have this feeling i dont have a leak..Im sure the million time Ive had this to the dealership they should of noticed something like that..I would think

Ive had the car checked for recalls and only ones that showed up were the power stearing and ignition..Is their a place online that I can check?

I dont always drive that slow..I was just trying to find a way to explain that Im not a speed demon on the roads.. I drive conservatively.

It is mostly short errand type kind of runs but man it cant be this bad.
Can it?
Sounds like slow a fuel leack to me. My base did that until I fixed the fuel like that was rusted.
 

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Discussion Starter #6 (Edited)
tire pressures? maybe a brake sticking
Whats your avg fuel economy. Figure it out the old fashion way.
Car rolls fine after letting off of the peddle a stearing wheel doesnt pull
I havent had the brakes checked for sticking yet but it really doesnt seem like they are

Ill do a fuel economy test next time i fill up which will be tomorrow i would say
the fuel economy is reading 10.3 km / 100km at the moment and by the end of the say it will ready 10.7 or more

Tire pressures are at 33lbs
 

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If your average speed is less than 50 km/h your fuel economy should be between 10 and 11 liters per 100Km. You can't expect a good fuel economy if you spend half the time idling at a light and doing stop and go in the city. I have 2 Cobalts an 07 and an 10. When driven similarly they produce exactly the same average fuel economy 8.9l/100kms. Here is the graph for both cars for this year. My oldest daughter drives the 10 (red bars on the graph). My youngest drives the 07. Both had the same rating until my oldest moved in town, look at the graph and guess when she moved.



---------- Post added at 01:23 PM ---------- Previous post was at 01:15 PM ----------

Here is that graph in mpg Imp

 

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If your average speed is less than 50 km/h your fuel economy should be between 10 and 11 liters per 100Km. You can't expect a good fuel economy if you spend half the time idling at a light and doing stop and go in the city. I have 2 Cobalts an 07 and an 10. When driven similarly they produce exactly the same average fuel economy 8.9l/100kms. Here is the graph for both cars for this year. My oldest daughter drives the 10 (red bars on the graph). My youngest drives the 07. Both had the same rating until my oldest moved in town, look at the graph and guess when she moved.

:) Thanks Coby7 for the detailed information..maybe Im just a cheapo and expect more then the expected..
Maybe I need to take the car for a good highway run.
To give an answer to your question that reminds me of high school math lol
now which mind you i barely passed Im thinking that she moved in late june early july?
I failed to mention that I too have 2 cobalts one being an 06 with 130,000 and not very well maintained like my 2010 the 06 is always driven the same too and its getting between 8.6 and 8.9 and has never went above 10
 

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Sounds like the fuel pump module. I know on some years it was a recall. Just had it done on my 07 SS and had it done a while back on my sons 07 LS. You would smell gas near the back of the car and no leaks on the ground either.
 

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Discussion Starter #10
Sounds like the fuel pump module. I know on some years it was a recall. Just had it done on my 07 SS and had it done a while back on my sons 07 LS. You would smell gas near the back of the car and no leaks on the ground either.
Thankyou.
Ive checked my vin number for recalls and the only ones i have are the
Power Steering and Ignition ones (done)

hmmmm
I will look further into this though
Car is still the same with no changes..wish I knew someone that lives in my town that is familiar with these cars.
 

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It's paid for in 2008?


Sent from the sexy electrician
 

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Car is getting worse
im now at 14.7l 100km
Ill have this car paid for in 2008 and cyah later cobalt
Are you driving with your foot on the brake? Did you try going for a highway run?
 

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Just so you know, before my O2 sensor finally set off the cel, it dropped my mpg by 7. Then about a month down the road my other O2 sensor went and dropped my fuel mileage again. Something to think about.


Sent from the sexy electrician
 

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Discussion Starter #15
It's paid for in 2008?
lol 2018 I bought the car in 2014

Are you driving with your foot on the brake? Did you try going for a highway run?
lol. No I drive with one foot
Yes the car is about 60 highway 40 city

Just so you know, before my O2 sensor finally set off the cel, it dropped my mpg by 7. Then about a month down the road my other O2 sensor went and dropped my fuel mileage again. Something to think about.
Thanks. I ve been thinking this also but Ive been having this problem for over a year now, unless mine is really slow to die
I will consider this though for sure
 

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If you do replace the O2 sensors but only ac delco ones. Any other brand and you'll be having a cel a week after changing them


Sent from the sexy electrician
 

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If you do replace the O2 sensors but only ac delco ones. Any other brand and you'll be having a cel a week after changing them


Sent from the sexy electrician
I put a DENSO from Rockauto on my 06 2.2l automatic over a year ago and no problems so far....I went with the Denso 'cause it was cheaper then the AC Delco and DENSO is the brand I've used before in Toyota's and never had problems with them.
 

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You're one of the lucky few. All of us have had problems with aftermarket O2 sensors.


Sent from the sexy electrician
 
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