LLT Major MPG loss - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

DandDC09 · 05-24-2014, 10:38 PM

Ok gear heads and info hoarders, I recently have noticed a big MPG loss on my LLT? I've gone from about 19 avg to 14 avg. Any ideas?

Here's some of the things I've done, but keep in mind, these were there when I had the higher avg about a month ago. I have 86,000+ miles, with a CAI intake, ported throttle body, manifold spacer, RX Catch can, 22" USW Forged wheels.

The reason I mention the 22's is because I know thats more rotating mass and would cause some reduction in mpg for the V6. They brought it down to 19 from 22, so I'm sure that can be ruled out.

So I'm gonna go to my dealer and see what they have to say next week, but thought I would run it through you guys too. I'm leaning towards maybe plugs and some fluid changes, since its somewhat recent of a loss. It's time for an oil change. The car does seem to have a little less power, but not throwing any codes. Loss of power meaning hesitant and sluggish, not running bad. My driving habits haven't changed and my city/HW use is the same too. I haven't used the auto start to warm up or AC cool the car yet, so not an idle time issue.

So i guess I'm curious to see what you all think? Oil change? Seafoam again?Plugs and wires? Fuse pull? Trans and diff fluid change? Filter cleaning? Timing Chain wear problem? Any ideas?

Thanks for any advice or help on this! This car should definitely get better than 14mpg on avg!

DSX_Camaro · 05-24-2014, 11:55 PM

Your car would thank you for changing all fluids and spark plugs, and the seafoam. Do you run 87 or 93?

scrming · 05-25-2014, 05:56 AM

Might try cleaning the MAF sensor. That's a very easy thing to try. Pick up some MAF cleaner at the parts store.

Other thing is it could be the timing chains are stretched enough for reduced power and MPG but not enough to throw a code.

I'm pretty sure your dealership will be useless unless you have a solid reproducible problem or code

rtcat600man · 05-25-2014, 06:00 AM

Sorry to hear about the MPG loss.

A tune-up of plugs certainly will not hurt. Forget the wires, there are none to change.

Fuse pull is for the V8's, so you can forget that one too.

Oil change should not affect MPG, but if it is due for one, routine maintenance is a must.

I don't believe the trans and read diff fluid would suddenly create a MPG issue. However changing the fluids will be a nice maintenance taken care of item. Both of those fluids are good for 100K miles but you are close enough it would be worth the time and effort now.

Air filter should be done at a regular interval. Not sure when you cleaned it last, (but broken record here) routine maintenance cleaning will thank - you in the long run.

If you have not thrown any codes for the timing chain, I would rule that out at the moment.

I have never done the seafoam, but if you have already done that and added the catch can, doing it again really should not do much for you as the catch can should have stopped most if not all of the oil build-up.

I would recommend cleaning the MAF thou, give that a try and see if it helps. Get some good fuel and go do a 25 mile test run on the highway and set the cruise at 70 MPH. Reset the DIC for MPG and report back what your MPG shows.

Below is a chart of mine from the past year, as I do this often on the way to work strictly out of boredom at 4 am.

scrming · 05-25-2014, 06:21 AM

Quote:

Originally Posted by rtcat600man

If you have not thrown any codes for the timing chain, I would rule that out at the moment.

Wife had the timing chains replaced twice in her Acadia... both times she complained about a drop in MPG and power shortly before the codes for the chain popped up...

sycraft · 05-25-2014, 06:40 AM

You may notice that your gas mileage has gone down a little bit in the past couple of months. Before we go blaming on ethanol (even though ethanol’s been in the fuel all year), you might want to consider the little-known fact that “summer blend” gas is actually different from “winter blend” gas.

What’s this? Gas isn’t the same all year round? Well no, it really isn’t.
Gasoline formulators vary the composition of gas in the hot summer months and the colder winter months, in order to meet emissions and air quality standards. This “reformulated” gas is blended in such a way that it has a lower vapor pressure in the summer and a high vapor pressure in the winter blends. This means the summer gas evaporates less and thus contributes less to the “evaporative emissions” which represent million of gallons of gasoline per year evaporated in the air. Winter gas is more volatile and evaporates more quickly, so it is ideal for it is used in the colder air of winter.

scrming · 05-25-2014, 07:05 AM

Quote:

Originally Posted by sycraft

You may notice that your gas mileage has gone down a little bit in the past couple of months. Before we go blaming on ethanol (even though ethanol’s been in the fuel all year), you might want to consider the little-known fact that “summer blend” gas is actually different from “winter blend” gas.

What’s this? Gas isn’t the same all year round? Well no, it really isn’t.
Gasoline formulators vary the composition of gas in the hot summer months and the colder winter months, in order to meet emissions and air quality standards. This “reformulated” gas is blended in such a way that it has a lower vapor pressure in the summer and a high vapor pressure in the winter blends. This means the summer gas evaporates less and thus contributes less to the “evaporative emissions” which represent million of gallons of gasoline per year evaporated in the air. Winter gas is more volatile and evaporates more quickly, so it is ideal for it is used in the colder air of winter.

Thing is MPG normally goes down in the Winter and UP in the Summer.... so his MPG should actually have gotten better not worse...

kelley1996 · 05-25-2014, 07:14 AM

Mine went through a stage like that. I did the norm clean throttle body,air cleaner,maf sensor and still had the same results. A friend had 2 brand new oxygen sensors on his bench for his LLT that he was going put in.....well he wrecked the car and gave me the front to sensors. I figured hell they are brand new I will just put them in. As soon as I put them in my mileage jumped back to where it was. The old ones looked fine and there was no codes. I do have a tune in it so I do not know why the new ones made a difference. Not saying this is your problem...just sharing my similar problem.

sycraft · 05-25-2014, 07:16 AM

depends on when his MPG were tracked, we are just coming out of winter gas, so if it has been the past few months he would have been affected by this.

scrming · 05-25-2014, 07:17 AM

Quote:

Originally Posted by kelley1996

Mine went through a stage like that. I did the norm clean throttle body,air cleaner,maf sensor and still had the same results. A friend had 2 brand new oxygen sensors on his bench for his LLT that he was going put in.....well he wrecked the car and gave me the front to sensors. I figured hell they are brand new I will just put them in. As soon as I put them in my mileage jumped back to where it was. The old ones looked fine and there was no codes. I do have a tune in it so I do not know why the new ones made a difference. Not saying this is your problem...just sharing my similar problem.

good point... O2 sensors could cause this also...

scrming · 05-25-2014, 07:28 AM

Quote:

Originally Posted by sycraft

depends on when his MPG were tracked, we are just coming out of winter gas, so if it has been the past few months he would have been affected by this.

Well, he did say "recently"... so i'm thinking with in the last month or so... i'm guessing if it has been winter blend and temps he would have noticed it Dec/Jan time frame...

sycraft · 05-25-2014, 07:32 AM

Quote:

Originally Posted by scrming

Well, he did say "recently"... so i'm thinking with in the last month or so... i'm guessing if it has been winter blend and temps he would have noticed it Dec/Jan time frame...

Very True... wonder if his cats are starting to collapse as well?

I would change plugs, Clean MAF and drive first...

DandDC09 · 05-25-2014, 02:07 PM

Thanks for the help guys!

Good points on all of it.

The mpg drop has been within the last two months. So the blend would still be the winter blend.

Gonna seafoam the gas first, clean the MAF, take it for a highway cruise(70 mph is our speed limit) and do the mpg reset and see what it gives me. We've been really humid her the last few days so I figure that dense air is gonna be a little less effective for me.

Im concerned it might be the chains. If so, I really hope it shows a code soon, so it can be warrantied! lol!

DandDC09 · 05-25-2014, 05:22 PM

Seafoam in the tank. Cleaned MAF. Hit the highway cruise at 70mph.

Averaged 27 one way and 25 back. Assuming head wind and tail wind.

Sounds a little low to me still. I averaged 29 to Table Rock fully loaded and 4 people. That was also on stock 20's though.

So, what's your opinions on this?

05-24-2014, 10:38 PM	#1
DandDC09 Drives: '10 2LT/RS, '13 Malibu Join Date: Nov 2009 Location: Wichita KS Posts: 476	LLT Major MPG loss Ok gear heads and info hoarders, I recently have noticed a big MPG loss on my LLT? I've gone from about 19 avg to 14 avg. Any ideas? Here's some of the things I've done, but keep in mind, these were there when I had the higher avg about a month ago. I have 86,000+ miles, with a CAI intake, ported throttle body, manifold spacer, RX Catch can, 22" USW Forged wheels. The reason I mention the 22's is because I know thats more rotating mass and would cause some reduction in mpg for the V6. They brought it down to 19 from 22, so I'm sure that can be ruled out. So I'm gonna go to my dealer and see what they have to say next week, but thought I would run it through you guys too. I'm leaning towards maybe plugs and some fluid changes, since its somewhat recent of a loss. It's time for an oil change. The car does seem to have a little less power, but not throwing any codes. Loss of power meaning hesitant and sluggish, not running bad. My driving habits haven't changed and my city/HW use is the same too. I haven't used the auto start to warm up or AC cool the car yet, so not an idle time issue. So i guess I'm curious to see what you all think? Oil change? Seafoam again?Plugs and wires? Fuse pull? Trans and diff fluid change? Filter cleaning? Timing Chain wear problem? Any ideas? Thanks for any advice or help on this! This car should definitely get better than 14mpg on avg! __________________

05-24-2014, 11:55 PM	#2
DSX_Camaro Drives: 2013 SW 2LT/RS LFX/AY6 Join Date: Feb 2013 Location: Orlando, FL Posts: 1,741	Your car would thank you for changing all fluids and spark plugs, and the seafoam. Do you run 87 or 93? __________________ K&N CAI, 1LE Strut Tower Brace, Elite Engineering Catch Can and Clean Side Separator, Apex Scoop w/ Washer Relocation Kit, CTS Front Calipers and Rotors, JacFab Ported Intake Manifold, JacFab Intake Manifold Spacer, 80mm Overkill Throttle Body, SS Brake Lines, Ideal Garage Master Cylinder, Monster Twin Disc Clutch, NPP Retrofit w/ Magnaflow Resonated X, ARH Catless Downpipes, JRE Built 3.45 Diff, 1LE Axles, 1LE Hubs, Overkill Tuned, BMR Anti Wheel-hop Kit Stage I, ACS TL1 Hood Insert, ZL1 Spoiler

05-25-2014, 05:56 AM	#3
scrming Red Brick of Vengeance! Drives: 12 Second Brick Join Date: Jun 2009 Location: at my pulpit Posts: 7,745	Might try cleaning the MAF sensor. That's a very easy thing to try. Pick up some MAF cleaner at the parts store. Other thing is it could be the timing chains are stretched enough for reduced power and MPG but not enough to throw a code. I'm pretty sure your dealership will be useless unless you have a solid reproducible problem or code __________________ 2011 Ford Flex EcoBoost Limited - 12.727 @ 109.790 MPH

05-25-2014, 06:00 AM	#4
rtcat600man having FUN now 13.66@101 Drives: 2010 2LT IOM Join Date: Nov 2009 Location: Clarkston, Michigan Posts: 9,230 View My Garage	Sorry to hear about the MPG loss. A tune-up of plugs certainly will not hurt. Forget the wires, there are none to change. Fuse pull is for the V8's, so you can forget that one too. Oil change should not affect MPG, but if it is due for one, routine maintenance is a must. I don't believe the trans and read diff fluid would suddenly create a MPG issue. However changing the fluids will be a nice maintenance taken care of item. Both of those fluids are good for 100K miles but you are close enough it would be worth the time and effort now. Air filter should be done at a regular interval. Not sure when you cleaned it last, (but broken record here) routine maintenance cleaning will thank - you in the long run. If you have not thrown any codes for the timing chain, I would rule that out at the moment. I have never done the seafoam, but if you have already done that and added the catch can, doing it again really should not do much for you as the catch can should have stopped most if not all of the oil build-up. I would recommend cleaning the MAF thou, give that a try and see if it helps. Get some good fuel and go do a 25 mile test run on the highway and set the cruise at 70 MPH. Reset the DIC for MPG and report back what your MPG shows. Below is a chart of mine from the past year, as I do this often on the way to work strictly out of boredom at 4 am. Attached Images __________________ MY BUILD

05-25-2014, 06:40 AM	#6
sycraft COTW 5/06/2013 Drives: 2017 Corvette Grand Sport-Ho-Vette Join Date: May 2012 Location: Milford, Michigan Posts: 3,201 View My Garage	You may notice that your gas mileage has gone down a little bit in the past couple of months. Before we go blaming on ethanol (even though ethanol’s been in the fuel all year), you might want to consider the little-known fact that “summer blend” gas is actually different from “winter blend” gas. What’s this? Gas isn’t the same all year round? Well no, it really isn’t. Gasoline formulators vary the composition of gas in the hot summer months and the colder winter months, in order to meet emissions and air quality standards. This “reformulated” gas is blended in such a way that it has a lower vapor pressure in the summer and a high vapor pressure in the winter blends. This means the summer gas evaporates less and thus contributes less to the “evaporative emissions” which represent million of gallons of gasoline per year evaporated in the air. Winter gas is more volatile and evaporates more quickly, so it is ideal for it is used in the colder air of winter. __________________ 2017 Grand Sport, Borla X Pipe.....Enough Said

05-25-2014, 07:14 AM	#8
kelley1996 Drives: '10 Camaro 2SS/RS/'17 Scat Pack Join Date: Aug 2013 Location: Danielson,Ct Posts: 179	Mine went through a stage like that. I did the norm clean throttle body,air cleaner,maf sensor and still had the same results. A friend had 2 brand new oxygen sensors on his bench for his LLT that he was going put in.....well he wrecked the car and gave me the front to sensors. I figured hell they are brand new I will just put them in. As soon as I put them in my mileage jumped back to where it was. The old ones looked fine and there was no codes. I do have a tune in it so I do not know why the new ones made a difference. Not saying this is your problem...just sharing my similar problem.

05-25-2014, 07:16 AM	#9
sycraft COTW 5/06/2013 Drives: 2017 Corvette Grand Sport-Ho-Vette Join Date: May 2012 Location: Milford, Michigan Posts: 3,201 View My Garage	depends on when his MPG were tracked, we are just coming out of winter gas, so if it has been the past few months he would have been affected by this. __________________ 2017 Grand Sport, Borla X Pipe.....Enough Said

05-25-2014, 02:07 PM	#13
DandDC09 Drives: '10 2LT/RS, '13 Malibu Join Date: Nov 2009 Location: Wichita KS Posts: 476	Thanks for the help guys! Good points on all of it. The mpg drop has been within the last two months. So the blend would still be the winter blend. Gonna seafoam the gas first, clean the MAF, take it for a highway cruise(70 mph is our speed limit) and do the mpg reset and see what it gives me. We've been really humid her the last few days so I figure that dense air is gonna be a little less effective for me. Im concerned it might be the chains. If so, I really hope it shows a code soon, so it can be warrantied! lol! __________________

05-25-2014, 05:22 PM	#14
DandDC09 Drives: '10 2LT/RS, '13 Malibu Join Date: Nov 2009 Location: Wichita KS Posts: 476	Seafoam in the tank. Cleaned MAF. Hit the highway cruise at 70mph. Averaged 27 one way and 25 back. Assuming head wind and tail wind. Sounds a little low to me still. I averaged 29 to Table Rock fully loaded and 4 people. That was also on stock 20's though. So, what's your opinions on this? __________________