[DcAudioImpala]

Over the 2 years i have owed my 2010 3.5l ffv it has been awesome but within the last year the fuel mileage has decreased immensely not going off the dash cause i know thats not 100 percent accurate i reset my trip every time i refuel and when i do the math divding the mileage to the amount of fuel i put into the car its in the 14.2 to 15.1 range average 180 to 210 a tank is there anything i could be doing to help a little bit used to get 18-20 mpg any help would be appreciated if there not much i can do then ohwell ill just keep feeding her addiction

 

[metalmike187]

Make sure your tires are properly inflated and your alignment is good. Check your air filter and replace as necessary. LiquiMoly or SeaFoam fuel system cleaner at the next fill-up. Has your driving style or commute changed in any way?

 

[Big Buford]

• As we transition from summer to winter (most of us are already in winter), the colder temperatures require more air be added to the tires above and beyond any leakage that's going on. It's rather common during fall and winter for lots of cars to have underinflated tires. Check to ensure proper inflation.
• Fuel System cleaner is a good idea...I use Gumout, but there are other good products as well as mentioned by metalmike187.
• Check to ensure everything is working properly wrt ignition...how many miles on your plugs, wires, etc.?
• Clean your Mass Air Flow (MAF) sensor.....ensure that you use ONLY MAF sensor cleaner and follow all directions not to damage the MAF sensor.
• Check for codes....what are the long-term and short-term fuel trims? Those might point to a problem....
• Here's the suggestion that nobody likes (myself included): SLOW DOWN! Accelerate gradually and slowly. High speeds on the highway equal less efficiency. If you drive like you're in F1 or NASCAR, then be prepared to pay for it at the pump!

Hope that helps and let us know what you find.....

 

[DcAudioImpala]

Make sure your tires are properly inflated and your alignment is good. Check your air filter and replace as necessary. LiquiMoly or SeaFoam fuel system cleaner at the next fill-up. Has your driving style or commute changed in any way?

I check tire pressure weekly and recently my driving style has calmed alot commute has changes its a little longer but less stop and go not necessarily highway

 

[DcAudioImpala]

• As we transition from summer to winter (most of us are already in winter), the colder temperatures require more air be added to the tires above and beyond any leakage that's going on. It's rather common during fall and winter for lots of cars to have underinflated tires. Check to ensure proper inflation.
• Fuel System cleaner is a good idea...I use Gumout, but there are other good products as well as mentioned by metalmike187.
• Check to ensure everything is working properly wrt ignition...how many miles on your plugs, wires, etc.?
• Clean your Mass Air Flow (MAF) sensor.....ensure that you use ONLY MAF sensor cleaner and follow all directions not to damage the MAF sensor.
• Check for codes....what are the long-term and short-term fuel trims? Those might point to a problem....
• Here's the suggestion that nobody likes (myself included): SLOW DOWN! Accelerate gradually and slowly. High speeds on the highway equal less efficiency. If you drive like you're in F1 or NASCAR, then be prepared to pay for it at the pump!

Hope that helps and let us know what you find.....

Replaced maf recently cause it would occasionally try to identify as a cammed ls4 on cold start just misfiring like all get out and had maf code and misfire codes no other codes in car as far as plugs and wires the nice old lady i bought the car from gave me a folder of all service records i will have to refer to that i had wondered if i should replace fuel pump considering its at 176k its still the original and gm didnt use an inline fuel filter on these from what i understand it just filters it out right at the pump but thats why i here im not the most knowledgeable i install audio systems for a living i dont play with performance

 

[Big Buford]

I would measure the fuel pressure first. If it's within limits, then there's no need to replace.
Your replaced MAF sensor is suspect...why would it identify as an LS4? Are you certain the installed MAF sensor is for your Impala? What brand? MAF Sensor is the type of component that I would be very wary regarding non-OEM parts. If it's not OEM, then I would measure the MAF Sensor output to ensure proper signals are being sent. This could be the culprit. Let us know what you find.....

 

[sheila]

Another culprit to check for is brake drag. After a drive, feel the center of each wheel by hand. If 1 or more is abnormally warm, it's time to pull the wheel and investigate. And don't forget about mandated winter blend fuel this time of year. It wreaks havoc with mpg.

 

[metalmike187]

Are you using regular gas or Flex Fuel? DO you have a way to check what the fuel trim level is?

 

[DcAudioImpala]

I would measure the fuel pressure first. If it's within limits, then there's no need to replace.
Your replaced MAF sensor is suspect...why would it identify as an LS4? Are you certain the installed MAF sensor is for your Impala? What brand? MAF Sensor is the type of component that I would be very wary regarding non-OEM parts. If it's not OEM, then I would measure the MAF Sensor output to ensure proper signals are being sent. This could be the culprit. Let us know what you find.....

I replaced my maf with gm acdelco maf sensor just what my dad has always taught be to do being he was a tech at a Buick Cadillac GMC store for 23 years i replaced the maf cause it was misfiring sounding rough then when i was replacing the i notice theres like a honeycomb piece in the air intake tube just before the maf that appeared to have been jostled a little out of position probably from the amout of vibration from my music i got that back in how it looked it should and did that maf it ran fine

 

[DcAudioImpala]

Are you using regular gas or Flex Fuel? DO you have a way to check what the fuel trim level is?

I just run regular i had only ran e85 through the car once cause it was $1.30 cheaper usually in my area its always exactly .70c cheaper. After that never ran it again. At the moment know sadly the car is a 10 and my snapon scaon tool will only read up to an 09 but i could use of the scan tools from the guys at work and check

 

[DcAudioImpala]

Another culprit to check for is brake drag. After a drive, feel the center of each wheel by hand. If 1 or more is abnormally warm, it's time to pull the wheel and investigate. And don't forget about mandated winter blend fuel this time of year. It wreaks havoc with mpg.

Okay will have to check that had recently done breaks on the car so could be a possibility as far as winter blend so far that has only caused me to lose and extra half a mile so not to major

 

[Bill58]

Alcohol Fuel %

Hello Everyone, I have a 2010 LT 3.5L I am the 2nd owner of the car and have owned it for almost 7 years. Today for the 3rd time since 2014 It has thrown a PO172 System too rich bank 1. Now the first time it did this I was pulling my hair out, long story but finally found the Alcohol Fuel %...

www.impalaforums.com

May be worth looking into.

 

[metalmike187]

I had similar issue with my 2008 LT that was posted in the article above. Check engine light, low fuel economy, etc. Replaced oxygen sensors to no avail. Used a cheapo scan tool that we had when I worked at AutoZone and it showed the fuel trim level was up near E85 levels. Made no sense since I never used E85 in that car. Turns out the oil from the K&N air filter I was using seeped off and gummed up the MAF. Cleaned it with MAF cleaner, removed and replaced the K&N with an STP filter and drove it. Fuel trim levels returned down to normal octane numbers (below 15% I believe) and never had an issue after. Might be worth the can of MAF cleaner to try it out.

 

[SinCitySinner]

Leaky injectors, catalytic converter, I wouldn't put any fuel cleaners in the tank. It will set a code for alcohol content at 100%. A regular code scanner cant clear that code. The flex fuel cars are very complex.