CMURDAx

So long story short, my dads truck took a dump so Im forced to DD my camaro while we fix his truck. After driving a full tank of 93 through the car I averaged my MPGs out and it came down to about 12.1... This was me being very light on the gas pedal also. My drive to work is 50/50 city/highway. Car is bone stock other than a cat back that now has no muffler, so just a 3" catback to axle dump. Any suggestions as to why its getting such bad mileage?

sawblade99Z

iTrader: (1)

Start with the simple things: clean your MAF, clean/replace air filter, replace fuel filter, or it could be bad gas. Also, do you sit in traffic with your AC on? If none of those fix it, you may need new plugs or O2 sensors. My Camaro gets around 24 mpg average with 40/60 city highway driving...even with some spirited driving thrown in, so yours should definitely be doing much better than that.

M4N14C

iTrader: (3)

Auto or M6? Also how are calculating your mileage?

CMURDAx

Air filter is still clean, I'm about to order a lid for it this week. And I've ran multiple tanks through of gas with seafoam as soon as I bought it. I just did plugs/wires/ oil change/ and fuel filter yesterday. I'm gonna see what that does. I found my fitting on the fuel filter leaking today so I gotta fix that tomorrow. Also it's an a4 and the way I'm calculating it is get down to the low light and divide my trip by 14 to get a combined average

CMURDAx

Also I rarely have the ac on in the car because its a ttop so normally they're out. It's never seen rain in the 5 months I owned it lol

M4N14C

iTrader: (3)

If I recall correctly, the tank for our cars is 15.8. But regardless, the best way to calculate your mileage is to obviously reset the trip timer when you first fill up. Drive as you regularly would. Then when you fill it up again, pay attention to the meter; particularly how many gallons your car took to fill up again. Take the exact value of your trip meter and divide it by the amount of gas you put in your car to get a very accurate MPG reading.

Let us know if your mini "tune up" help any

sawblade99Z

iTrader: (1)

16.8 And OP, calculate your mileage like he said. Only way to do it, if you ask me. Report back when you fill up again!

NC01TA

Good advice from everyone.
12 mpg is way too low for a 'stock' LS1. I'm always driving a combined city/hwy where I live (A4 tranny) and probably fall right around the 20 mpg area in my 'stock' car. I would imagine if I lived in a big city only I'd be round 16 - 17 mpg with certain degrees of traffic. Always use 93 here as well.

CMURDAx

Well I got the fuel leak fixed today and took the MAF off and cleaned that as well. Ill let you all know what it looks like through out the week as I drive it more, thanks for the quick replys

mr.beachcomber

The only thing that I would add to this excellent advice is don't overfill your tank or your readings will be off. I wanted to double check my Vette's mileage as calculated by the ECU, so I did this for a month. As soon as the automatic cutoff engaged, I stopped pumping and used the gallons figure off the pump and divided my trip odo mileage by that amount. It worked great!

pewterformula

iTrader: (2)

The true best way to track your MPG is doing it over several fillups. If you have an android phone, download the app called aCar. You can track your fuel purchases and mileage, your maintenance schedule, car accessory purchases, etc. There are many apps out there that do similar functions, this is just the one I like and use. BTW, I average about 26 MPG highway driving to work with my 01 SS M6.

JDEP162

that seems really low. mix of city/hiway/romping i still get at least 20. on a long cruise 25 highway with cruise set at 62mph.

thunderstruck507

iTrader: (18)

fuel gauges and lights are highly inaccurate for calculating mileage

reset the odometer, fill up, drive, fill up at the same gas station and pump if possible, divide the mileage on odometer by the gallons used to fill

CMURDAx

Thats what Im gonna be doing with my next fill up. Currently Im at half a tank and at i believe 98 miles on the trip... granted there is 5 30-90 pulls on this tank lol

ThatOneKid

I have the same problem. I just bought the car, mods in sig, and on my first tank of 50/50 city/hwy i got 12.6. Changed the oil with M1 5w-30 and my mpg's have increased a tiny bit. Gonna go with some new plugs/wires, clean the air filter, MAF, and get a set of those ASP underdrive pulleys. Then hopefully I can get 20ish! I just hope Massa Obama doesn't bomb poor little Syria, then gas will really be high!

flattusmaximus78

iTrader: (1)

Depending on how your dumps are positioned, they could be throwing off your fuel trims. Cutouts do this often. It's easy with no muffler.

CMURDAx

I drove the full tank and at fill up I averaged 16.4 MPG. Id like to see 20 out of it but this is better than before by all means. Also the dump is right where the muffler connected. Literally all I did was cut the muffler off because it was rotted on both outlets, so its after the axle

M4N14C

iTrader: (3)

That's around what I get but I do basically 100% city. But yea, plugs, wires, fuel/air filter, injectors, O2 sensors and driving style are all culprits to cut down your mileage.

If I drive like my grandma (all shifts before 1500RPM, cruise at 1000RPM and NO wot pulls ) I might catch 20. But anyone who buys an LS1 then tries to hyper-mile it should be shot