Excessive fuel consumption

Zap city · 10-24-2016, 11:57 PM

Love my car and it has been FLAWLESS since I bought it in June. My only concern is that it seems to be burning an inordinate amount of fuel. I've been averaging about 13mpg around town. The highest I've seen has been 18.5 on the highway. I had my tech run a scan on it when I took it in for the last oil change and he could find nothing wrong to account for the poor mileage. Yes I drive it spirited, but even doing my best to creep, all I was able to get was 14 in town. Car is an MN6 btw. I'm wondering if I need a tune to lean it out a bit. All input is appreciated?

SSport16 · 10-25-2016, 12:28 PM

Quote:

Originally Posted by Zap city

Love my car and it has been FLAWLESS since I bought it in June. My only concern is that it seems to be burning an inordinate amount of fuel. I've been averaging about 13mpg around town. The highest I've seen has been 18.5 on the highway. I had my tech run a scan on it when I took it in for the last oil change and he could find nothing wrong to account for the poor mileage. Yes I drive it spirited, but even doing my best to creep, all I was able to get was 14 in town. Car is an MN6 btw. I'm wondering if I need a tune to lean it out a bit. All input is appreciated?

City you are not going to get much better than you are already getting...on the highway is where you will get close to 30 mpg or even higher.

But then again this is not a small econobox, not really meant for fuel savings.

nbryant · 10-25-2016, 06:17 PM

Lean it out?

18 on the highway, how long was the trip? Short spurts in town and you will not see much better then 14-17. I drive 15 miles to work (back and forth) total a day and get 17 on the low side. I take it on the road for a 100+ mile trip and I have gotten up to 29+. It loves long trips.

Zap city · 10-25-2016, 07:56 PM

Yes, lean out to air fuel mixture. The car may be running rich for some reason not detected on the scan. I drove over 800 miles this past weekend and only averaged 18. Thats what I'm saying. If you are getting 17 lowside, I'm getting 13 average in town. I'm not unrealistic or a newbie to performance cars- last one was a 2012 Z with an LS7 in it. I'm just going on what I've seen other get here and it seems that I'm burning a lot of gas. Any others suggestions would be appreciated as to what may be the cause?

Quote:

Originally Posted by nbryant

Lean it out?

18 on the highway, how long was the trip? Short spurts in town and you will not see much better then 14-17. I drive 15 miles to work (back and forth) total a day and get 17 on the low side. I take it on the road for a 100+ mile trip and I have gotten up to 29+. It loves long trips.

cigarfan · 10-25-2016, 09:23 PM

Been driving very spirited lately...getting 17-18 mpg around town. Not exaggerating either. Albeit 6-8 gallons per week to & from work, but definitely no babying to say the least.

SpookShow'84 · 10-25-2016, 10:14 PM

Don't lean it out yourself and void the warranty. Talk to your dealer and ask about seeing if it's running rich or has a sensor reading wrong, and if it's not those you can probably chalk it up to your personal driving style. It is a 455/455 car with 3.73's.

nbryant · 10-26-2016, 04:39 PM

Quote:

Originally Posted by SpookShow'84

Don't lean it out yourself and void the warranty. Talk to your dealer and ask about seeing if it's running rich or has a sensor reading wrong, and if it's not those you can probably chalk it up to your personal driving style. It is a 455/455 car with 3.73's.

Thanks Spook, this was what I was implying with my question to him. Just got home and was going to provide a similar response but you beat me to it.

Emoto · 10-26-2016, 04:47 PM

Don't go changing mixture without being able to measure what you're doing. We are not talking about a 283 with a 2bbl carb here.

As long as the car is under warranty, make this the dealer's problem. Let them measure and report to you the exhaust gas analysis as a start.

I am averaging about 22 mpg in mixed driving, mostly taking it easy with a little bit of frisky behavior mixed in.

TedJS · 10-26-2016, 07:48 PM

How are you measuring fuel economy? And how can you "lean out" the air/fuel mixture on an engine with a closed loop feedback fuel control system?

Zap city · 10-26-2016, 09:30 PM

Actually I just went back and read my original post. My question was not clear. I understand tuning my car will void the warranty. I understand I should have the dealer look at it- which I did. I'm actually checking my average with computer in the DIC and double checking it the old fashioned way by taking miles driven divided by gallons to top off. With all due respect, I get all this stuff. I simply wanted to know if anyone had any specific idea as to what could be causing excessive fuel burn from a technical standpoint- either from a similar experience with their own cars or something they have heard through the grapevine. Again, thanks for the help. I would like to avoid 10 pointless trips to the dealer if possible. Sorry for the confusion in the original post.

JBinSD · 10-31-2016, 06:19 PM

fwiw, I have a 2SS MN6 and am now getting about 13.2 mpg, even when I "baby" it. I have 750 miles on it, so I"m hoping it will loosen up and get a bit better, but we didn't buy these to save trees. Even the 1-4 skip shift and coasting haven't helped my mileage, so I feel your pain, that is, until I hear the roar. . . When gas goes up to $5/gallon again, will be much more painful. . .

asimpleguy · 11-03-2016, 04:05 PM

Quote:

Originally Posted by Zap city

Actually I just went back and read my original post. My question was not clear. I understand tuning my car will void the warranty. I understand I should have the dealer look at it- which I did. I'm actually checking my average with computer in the DIC and double checking it the old fashioned way by taking miles driven divided by gallons to top off. With all due respect, I get all this stuff. I simply wanted to know if anyone had any specific idea as to what could be causing excessive fuel burn from a technical standpoint- either from a similar experience with their own cars or something they have heard through the grapevine. Again, thanks for the help. I would like to avoid 10 pointless trips to the dealer if possible. Sorry for the confusion in the original post.

I have an SS with 20000 miles, yes, twenty thousand lol. Anyway, after I made my second oil change at 5000 miles my car was noticeably better on gas mileage if you have yet to reach that point then I sguest you wait and see if it helps. After that it's probably your best bet toleave it up to the dealership to handle it. GOOD luck

MrChrisLS3 · 11-07-2016, 12:10 PM

There are so many factors involved in the avg mpg number. Keep in mind that the number is effected when sitting at idle, so heavy traffic, long lights, idling and revving while showing off the car, all of that will get figured in to that number.

How quickly you accelerate effects that number as well. You say there is some "spirited" driving involved. So, for example, on the highway, if you're downshifting to get thrown back in the seat going from 60-80, you use a lot more gas.

I know some stating much higher mpg, however, they may be using the car in a completely different manner than you are. I would think that if you were experiencing a fuel/engine issue that cause a 4-5 mpg difference under the exact same conditions, your display would look like Christmas in Times Square with all the lights. Give it some time, it should get better once you get past the 'honeymoon" stage.

Paully104 · 11-08-2016, 08:02 AM

Just to rule out something silly, what octane fuel are you using? Also where are you getting your gas? Can you try another location and see if you notice a difference?

10-24-2016, 11:57 PM	#1
Zap city Drives: 2019 ZL1 1LE, MN6, SGM Join Date: Jun 2016 Location: North Carolina Posts: 223	Excessive fuel consumption Love my car and it has been FLAWLESS since I bought it in June. My only concern is that it seems to be burning an inordinate amount of fuel. I've been averaging about 13mpg around town. The highest I've seen has been 18.5 on the highway. I had my tech run a scan on it when I took it in for the last oil change and he could find nothing wrong to account for the poor mileage. Yes I drive it spirited, but even doing my best to creep, all I was able to get was 14 in town. Car is an MN6 btw. I'm wondering if I need a tune to lean it out a bit. All input is appreciated?

10-25-2016, 06:17 PM	#3
nbryant Drives: 2016 2SS Red Hot Join Date: May 2016 Location: Southern Maryland Posts: 627	Lean it out? 18 on the highway, how long was the trip? Short spurts in town and you will not see much better then 14-17. I drive 15 miles to work (back and forth) total a day and get 17 on the low side. I take it on the road for a 100+ mile trip and I have gotten up to 29+. It loves long trips. __________________ 2SS, A8, NPP, Nav, Sun Roof, Bose Audio, MM Catch Can, RPI chin splitter

10-25-2016, 10:14 PM	#6
SpookShow'84 Bump in the night Drives: '84 Monte Carlo SS, '15 Optima Join Date: Oct 2015 Location: U.S.A. Posts: 744 View My Garage	Don't lean it out yourself and void the warranty. Talk to your dealer and ask about seeing if it's running rich or has a sensor reading wrong, and if it's not those you can probably chalk it up to your personal driving style. It is a 455/455 car with 3.73's. __________________ https://youtu.be/Acui13Vz5Lk

10-26-2016, 04:47 PM	#8
Emoto Sure, why not? Drives: 2016 Camaro 2SS, Jeep JKU Rubicon Join Date: Mar 2015 Location: SE Mass Posts: 1,538	Don't go changing mixture without being able to measure what you're doing. We are not talking about a 283 with a 2bbl carb here. As long as the car is under warranty, make this the dealer's problem. Let them measure and report to you the exhaust gas analysis as a start. I am averaging about 22 mpg in mixed driving, mostly taking it easy with a little bit of frisky behavior mixed in. __________________ This is that witty and clever statement that makes you chuckle.

10-26-2016, 09:30 PM	#10
Zap city Drives: 2019 ZL1 1LE, MN6, SGM Join Date: Jun 2016 Location: North Carolina Posts: 223	Actually I just went back and read my original post. My question was not clear. I understand tuning my car will void the warranty. I understand I should have the dealer look at it- which I did. I'm actually checking my average with computer in the DIC and double checking it the old fashioned way by taking miles driven divided by gallons to top off. With all due respect, I get all this stuff. I simply wanted to know if anyone had any specific idea as to what could be causing excessive fuel burn from a technical standpoint- either from a similar experience with their own cars or something they have heard through the grapevine. Again, thanks for the help. I would like to avoid 10 pointless trips to the dealer if possible. Sorry for the confusion in the original post. Last edited by Zap city; 10-26-2016 at 10:24 PM.

10-25-2016, 09:23 PM	#5
cigarfan Drives: 16' Camaro 2/SS BlackMosaic A/8 NPP Join Date: Jan 2016 Location: SWFL Posts: 112	Been driving very spirited lately...getting 17-18 mpg around town. Not exaggerating either. Albeit 6-8 gallons per week to & from work, but definitely no babying to say the least.

10-26-2016, 07:48 PM	#9
TedJS Drives: 2016 Camaro SS Join Date: Jul 2016 Location: Cleveland, OH Posts: 92	How are you measuring fuel economy? And how can you "lean out" the air/fuel mixture on an engine with a closed loop feedback fuel control system?

10-31-2016, 06:19 PM	#11
JBinSD Drives: '23 LT Vert M6'16 Hyper 2SS Vert MT Join Date: Sep 2016 Location: Carlsbad, San Diego, CA Posts: 604	fwiw, I have a 2SS MN6 and am now getting about 13.2 mpg, even when I "baby" it. I have 750 miles on it, so I"m hoping it will loosen up and get a bit better, but we didn't buy these to save trees. Even the 1-4 skip shift and coasting haven't helped my mileage, so I feel your pain, that is, until I hear the roar. . . When gas goes up to $5/gallon again, will be much more painful. . .

11-07-2016, 12:10 PM	#13
MrChrisLS3 Drives: 2018 1SS M6 Join Date: Nov 2014 Location: Houston Posts: 2,617	There are so many factors involved in the avg mpg number. Keep in mind that the number is effected when sitting at idle, so heavy traffic, long lights, idling and revving while showing off the car, all of that will get figured in to that number. How quickly you accelerate effects that number as well. You say there is some "spirited" driving involved. So, for example, on the highway, if you're downshifting to get thrown back in the seat going from 60-80, you use a lot more gas. I know some stating much higher mpg, however, they may be using the car in a completely different manner than you are. I would think that if you were experiencing a fuel/engine issue that cause a 4-5 mpg difference under the exact same conditions, your display would look like Christmas in Times Square with all the lights. Give it some time, it should get better once you get past the 'honeymoon" stage.

11-08-2016, 08:02 AM	#14
Paully104 Novice Driver Drives: 2016 2SS Silver Join Date: Jul 2016 Location: Tx Posts: 116 View My Garage	Just to rule out something silly, what octane fuel are you using? Also where are you getting your gas? Can you try another location and see if you notice a difference?

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