Bad gas mileage with new exhaust on SS LS3 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Larz29 · 09-21-2010, 09:21 AM

So I just installed a flowmaster cat back exhaust this past weekend, then reflashed my diablosport predator 93 tune. I noticed a noticable performance gain, but my gas mileage tanked.. Before the exhaust i was averaging 16.5 mpg with all in town driving, and now by driving very very nice I'm barely getting 15 mpg.

Seriously everyone I talked to said my mileage would improve with a tune and aftermarket exhaust, and CAI... Not the case with me! LOL.

Do I need a custom tune? Any ideas? Thoughts?

OneQuickGP · 09-21-2010, 10:32 AM

If you really are getting that much worse gas mileage it has to be something wrong with the tune. I'd contact them for help for sure.

Mr_Draco · 09-21-2010, 10:42 AM

Actually getting worse gas mileage is fairly common. Not because of the mods and the tune but because humans subconsciously change their driving habits without realizing it after during such mods.

Sevn86 · 09-21-2010, 10:46 AM

Quote:

Originally Posted by Mr_Draco

Actually getting worse gas mileage is fairly common. Not because of the mods and the tune but because humans subconsciously change their driving habits without realizing it after during such mods.

I agree..people dont realise but they tend to stomp on the gas pedel just so they could hear their exhaust and that causes them to get bad gas mileage...

vinman · 09-21-2010, 10:50 AM

So just have your dog drive it and you won't lose any gas mileage

EFI · 09-21-2010, 11:00 AM

I definitely agree with the above posters saying that it's prolly you or the way you drive that changed since the mods. It makes sense that with a new tune and better sounding exhaust you would give it more gas than normal.

A good test would be cruising on the highway, not in town where driving habits and traffic can greatly affect the mileage. How can you be sure that you didn't hit extra traffic or a few more lights? At least on the highway cruising at 65mph is the same everyday.

Russell James · 09-21-2010, 11:05 AM

In town driving with so much stop and go is not a very accurate measure of mpgs.

Plus, more power = more fuel. You put in a performance tune. If you put in an mpg tune, I'd be concerned with the results. You put in their most aggressive tune which ups the fuel and spark for more power on premium fuel.

I'd bet your throttle response feels snappier. I think they tinker with the throttle reaction table to make the actual engine throttle react faster to the gas pedal moving. Making the throttle open faster will not improve the mpgs.

I've used that tune before and it does have a real nice throttle response to it, at the price of a little more fuel. Which if you are performance tuning, is the expected result.

Mark Myles · 09-21-2010, 11:28 AM

Quote:

Originally Posted by Sevn86

I agree..people dont realise but they tend to stomp on the gas pedel just so they could hear their exhaust and that causes them to get bad gas mileage...

I also installed cat back Flowmaster and noticed I was visiting the gas station more often.

Can't help it, the sound makes you want to....

M

mr. anderson · 09-22-2010, 08:41 AM

Also I would wait a tank of gas before noting gas mileage especially if you put in a new tune.

SlingShot · 09-22-2010, 08:47 AM

Quote:

Originally Posted by Mark Myles

I also installed cat back Flowmaster and noticed I was visiting the gas station more often.

Can't help it, the sound makes you want to....

M

Same here !!!

I think 15mpg is pretty good ...

Bonanza7 · 09-22-2010, 08:48 AM

Yeah, I put Flowmasters on my 4.6 Mustang, and mileage went down right away. Just couldn't get enough of that V8 sound.

Chrisrp454 · 09-22-2010, 08:49 AM

I have to say I agree. Try this lower your back seat down, you will hear the exhaust a lot more than normal, and I found myself enjoying it too much!

Quote:

Originally Posted by Sevn86

I agree..people dont realise but they tend to stomp on the gas pedel just so they could hear their exhaust and that causes them to get bad gas mileage...

ffrcobra_65 · 09-22-2010, 11:07 AM

You have shot your powertrain warranty by installing a tune. Spending a couple of $$ more on gas should not be a big deal. just sayin..

tony1 · 09-22-2010, 11:29 AM

Driving very very easy on it in the City Iam 13-14 ... it's not driving habits (when you watching the MPG Gauge and trying to see your Best Milage you can get) .. The OP states he was also trying to see his best milage by driving very easy on it. After you see what you can get then you drive like you really should be.

09-21-2010, 09:21 AM	#1
Larz29 Drives: 2010 camaro ss LS3 cyber grey Join Date: Aug 2010 Location: Madison,wi Posts: 226	Bad gas mileage with new exhaust on SS LS3 So I just installed a flowmaster cat back exhaust this past weekend, then reflashed my diablosport predator 93 tune. I noticed a noticable performance gain, but my gas mileage tanked.. Before the exhaust i was averaging 16.5 mpg with all in town driving, and now by driving very very nice I'm barely getting 15 mpg. Seriously everyone I talked to said my mileage would improve with a tune and aftermarket exhaust, and CAI... Not the case with me! LOL. Do I need a custom tune? Any ideas? Thoughts?

09-21-2010, 10:32 AM	#2
OneQuickGP Drives: 2010 IOM 2SS/RS Join Date: Feb 2010 Location: Bonne Terre, Mo. Posts: 85	If you really are getting that much worse gas mileage it has to be something wrong with the tune. I'd contact them for help for sure. __________________ St. Francois Co. Street Racers

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09-21-2010, 10:42 AM	#3
Mr_Draco Drives: 2SS/RS Join Date: Sep 2008 Location: Western North Carolina Posts: 7,182	Actually getting worse gas mileage is fairly common. Not because of the mods and the tune but because humans subconsciously change their driving habits without realizing it after during such mods.

09-21-2010, 10:50 AM	#5
vinman The BBOMG fill-in husband Drives: 2015 2SS/RS 1LE AKA V1LE Join Date: Aug 2010 Location: Elmira, NY Posts: 4,458 View My Garage	So just have your dog drive it and you won't lose any gas mileage

09-21-2010, 11:00 AM	#6
EFI Drives: something faster than you Join Date: Aug 2010 Location: where dem hoes be Posts: 315	I definitely agree with the above posters saying that it's prolly you or the way you drive that changed since the mods. It makes sense that with a new tune and better sounding exhaust you would give it more gas than normal. A good test would be cruising on the highway, not in town where driving habits and traffic can greatly affect the mileage. How can you be sure that you didn't hit extra traffic or a few more lights? At least on the highway cruising at 65mph is the same everyday.

09-21-2010, 11:05 AM	#7
Russell James Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009 Location: Mich Posts: 4,482	In town driving with so much stop and go is not a very accurate measure of mpgs. Plus, more power = more fuel. You put in a performance tune. If you put in an mpg tune, I'd be concerned with the results. You put in their most aggressive tune which ups the fuel and spark for more power on premium fuel. I'd bet your throttle response feels snappier. I think they tinker with the throttle reaction table to make the actual engine throttle react faster to the gas pedal moving. Making the throttle open faster will not improve the mpgs. I've used that tune before and it does have a real nice throttle response to it, at the price of a little more fuel. Which if you are performance tuning, is the expected result.

09-22-2010, 08:41 AM	#9
mr. anderson Drives: 2015 Camaro 2SS 1LE Join Date: Aug 2010 Location: Moore, OK Posts: 113	Also I would wait a tank of gas before noting gas mileage especially if you put in a new tune.

09-22-2010, 08:48 AM	#11
Bonanza7 Account Suspended Drives: 2010, Rally Yellow, Black stripes Join Date: Jul 2010 Location: Phoenix Posts: 2,363	Yeah, I put Flowmasters on my 4.6 Mustang, and mileage went down right away. Just couldn't get enough of that V8 sound.

09-22-2010, 11:07 AM	#13
ffrcobra_65 Account Suspended Drives: SuperCharged 2SS/RS IOM MN6 Join Date: May 2009 Location: CA Posts: 5,094	You have shot your powertrain warranty by installing a tune. Spending a couple of $$ more on gas should not be a big deal. just sayin..

09-22-2010, 11:29 AM	#14
tony1 Drives: 2SS/RS Vortech/L99 Join Date: Jan 2010 Location: CHICAGO Posts: 474	Driving very very easy on it in the City Iam 13-14 ... it's not driving habits (when you watching the MPG Gauge and trying to see your Best Milage you can get) .. The OP states he was also trying to see his best milage by driving very easy on it. After you see what you can get then you drive like you really should be.