2012 2LT - Horrible gas mileage

[SnowVert]

I've averaged 19.811 actual MPG over the life of this car with 7230 miles. I averaged 18.958 over the life of my 2012 vert (18048 miles).

And just an fyi for the convertible guys out there, through multiple long road trips and thorough testing, I average almost exactly 1mpg less over a full tank on the highway with the top down.

[blackswan]

Originally Posted by BBS

Computer might be messed up.

This.

Verify manually.

[Jalberdi99]

Do i reset it before filling up or after filling up? Or it doesn't matter?

[tonyko1]

Originally Posted by SC2150

The more oil is ingested into the intake, the more the intake valves coke up, the less efficient the engine is, the more detonation takes place, the more timing is pulled, and less power the worse the MPG.

Also, this makes using Premium (93) all the more critical to try and reduce the detonation.

Let me know if you need more details, pictures, and solutions.

Okay, it is V6, it doesn't need 93 octane........it is "tuned" from the factory to accept 87 octane as engineered. Are you going to suggest the famed 5/20 Fuse pull, ha.

Just a guess here, you are going to suggest a catch-can...........ugh.



But please, don't drag out those file photos of the super-uber carbon coated piston rods and such, it is getting old.

And you can save everyone time by linking to the mechanical section when you do your 9 page thesis on what is wrong with all engines not having a catch-can, no need to clog the thread here.

Thank you.

[Angrybird 12]

Originally Posted by Jalberdi99

Do i reset it before filling up or after filling up? Or it doesn't matter?

When you get in the car after filling or just before you get out before filling. It really dosen't matter. Just never reset it between fillups and compare it to a manual calculation. It will be way off then.
I have 32 years experience in flow calculating instrumentation and unless your injectors are severely clogged or worn the calculations done by the Computer will be fairly accurate. The more wear or clogging of the injectors will affect the calculations. The calculation done by the computer relies on the pulse length that the injector remains open. The more pulses the more fuel used. But I would expect it the injector problem would have to be so bad that the actual performance decrease would also be noticed.
Even though the fuel pumps where you get gas are supposed to be calibrated and certified the longer it goes between calibrations the more error it has in the amount of fuel it delivers. Another factor in manual calculations is different pumps have different cutoff points, what this can do is cause a inconsistent refueling of your vehicle. All of which affects calculations of fuel mileage.

The best way to figure mileage to reduce percentage of error is to add up the gallons over several tank refills. Then you can use the miles you drove during the same period. I usually do that when on trips, and its then when I have found the DIC to be fairly close to my manual Calculation.

I hope this helps.

[My Caroline]

Originally Posted by Angrybird 12

It has to take the one second you floored it into the calculation along with the 30 minutes you cruise because its an overall average... Sure the DIC readout will be different if you reset it every time you shut the car off. If you want a good average mpg you have to only reset it at fill up. If you don't reset it between fill ups it DOES run for the whole tank. Every time you reset it between fill ups it screws up the entire calculation.


Did you reset the DIC any other time than when you filled up your car? If you did you screwed up the DIC's ability to show your true MPG for that tank. Again It has to take that 2mpg in account because you are using that much fuel that's why it's called an AVERAGE MPG.
I have owned many cars with the average MPG readouts and have never found one to be more than 1/2 mpg off for a tank of gas.

I'll put it this way, math doesn't lie. When the math is different than the DIC, I'll trust the math. Of course when I first got the car I let the DIC run the whole tank. I, like the OP as concerned that my MPG was low because of what the DIC was telling me. So I calculated it with math and found that th DIC was in fact low.

I have noticed that the DIC is 5-8 miles per gallon LOWER than what the math says. I have noticed my MPG DOES NOT run the entire tank. It stops averaging. If I drive half a tank at 15 mpg and the last half on he highway getting 30 the AVERAGE should be in the 20s (about 22), not 15. And my math has proven this to me.

Your DIC and math will be close if you drive the whole tank out in a trip. But if you're like me and take a week or two to empty the tank it just isn't right.

[Angrybird 12]

Originally Posted by My Caroline

I'll put it this way, math doesn't lie. When the math is different than the DIC, I'll trust the math. Of course when I first got the car I let the DIC run the whole tank. I, like the OP as concerned that my MPG was low because of what the DIC was telling me. So I calculated it with math and found that th DIC was in fact low.

I have noticed that the DIC is 5-8 miles per gallon LOWER than what the math says. I have noticed my MPG DOES NOT run the entire tank. It stops averaging. If I drive half a tank at 15 mpg and the last half on he highway getting 30 the AVERAGE should be in the 20s (about 22), not 15. And my math has proven this to me.

Your DIC and math will be close if you drive the whole tank out in a trip. But if you're like me and take a week or two to empty the tank it just isn't right.

Sorry you are still wrong. It dosen't work the way you describe. What makes you think it stops averaging when you shut off the car? Does it reset on its own back to 0 when you first get in the car and start it? if its reading 18mpg when you shut it off. As soon as you restart it it should still read 18. Like I have said I have owned several cars with this feature and if yours is doing as you describe then you have a problem. It does not matter if you are on a trip or it takes two weeks to run out a tank. It should be close.
By the way how can you tell your getting 15 mpg for half a tank and 30 for the second half? If you reset your DIC at half a tank on the gauge (which at half a tank indicated you may have used more or less than a half tank) do you run it to completely empty? How do you know how much gas you used for the first half a tank? How do you know how much you used on the second half? You cannot figure it out the way you say. The math won't work out. There is just to much error by GUESSING how much gas you have used in each half tank.

[TooCool5]

Originally Posted by tonyko1

Okay, it is V6, it doesn't need 93 octane........it is "tuned" from the factory to accept 87 octane as engineered. Are you going to suggest the famed 5/20 Fuse pull, ha.

Just a guess here, you are going to suggest a catch-can...........ugh.



But please, don't drag out those file photos of the super-uber carbon coated piston rods and such, it is getting old.

And you can save everyone time by linking to the mechanical section when you do your 9 page thesis on what is wrong with all engines not having a catch-can, no need to clog the thread here.

Thank you.

Couldn't have said it better..... Wow he never gives up $$$$$$.

[My Caroline]

Originally Posted by Angrybird 12

Sorry you are still wrong. It dosen't work the way you describe. What makes you think it stops averaging when you shut off the car? Does it reset on its own back to 0 when you first get in the car and start it? if its reading 18mpg when you shut it off. As soon as you restart it it should still read 18. Like I have said I have owned several cars with this feature and if yours is doing as you describe then you have a problem. It does not matter if you are on a trip or it takes two weeks to run out a tank. It should be close.
By the way how can you tell your getting 15 mpg for half a tank and 30 for the second half? If you reset your DIC at half a tank on the gauge (which at half a tank indicated you may have used more or less than a half tank) do you run it to completely empty? How do you know how much gas you used for the first half a tank? How do you know how much you used on the second half? You cannot figure it out the way you say. The math won't work out. There is just to much error by GUESSING how much gas you have used in each half tank.

Didn't read it. But ok.

[MBS]

Yah do it the old fashion way .Fill it up ,then keep track of your miles . Fill it up again and divide the gallons by total miles driven. No way can you get that kind of mileage unlesss you have a gas leak.

[RSloth]

I daily drive and have a bit of a led foot. i sit at 18.4 and thats with a Cold air intake

[TastyBake]

Originally Posted by BreakingBad

I forget what place I usually stop at, but I will roll with Sunoco and/or Shell next fill up to see if that helps, as far as fuel injector cleaner - is that really necessary with only 6100 miles?

It only takes one time for it to become clogged if you go to a station that doesn't change it pump filters.

[Chevrolet Customer Svc]

Originally Posted by BreakingBad

So to avoid the 'this has already been discussed' replies:

I understand that how you drive the vehicle will affect mileage. I understand city vs highway will (obviously) affect mileage. I know that maintaining the vehicle (oil) along with other things needs to be done to ensure optimal performance.

Mon-Fri I'm city driving - max speed being 30, 35, sometimes 40 depending. Weekends I hit the highway.

When I first got the vehicle, my 'average' mileage was 15-16mpg. Keep in mind, this is the V6 so I should be closer to 17-18. Either way, I figured they're 'always estimates' and kinda dealt with it.

Fast forward - 6100 miles on the car and here is my 'average' gas mileage:

11.4. REALLY?

If there is no rational explanation for this, it's going in the shop. It has slowly decreased from 15-16 to 14, 13, 12, now 11. Hell, I wouldn't be surprised if I hit 10 or 9.

Coincidentally whenever I turn on the heat, I'm hearing a low, high-pitched 'flutter' noise, audible to anyone in the vehicle. Only occurs when the heat is on, and you hear it 'flutter' out when you turn the heat off. Also, when traveling at slow speeds (5mph and under) there is an audible noise coming from car, some people described it as a grinding noise but it seems to only occur when the heat is on, or is more audible when the heat is on. Some people also said that when braking, there is a 'known issue' with camaros where there is grinding/noise. Not sure if that would be related, but I'm almost positive the car has to go in.

Please let us know if your gas mileage improves. Also if you decide to go to a dealership, please let us know the outcome.

Brandon
Chevrolet Customer Service