kevm14

Actually the PCM uses injector pulse width * rpm and takes into account O2 sensor fuel trims to compute consumed fuel. When I fuel up I compare that to the fuel used in the DIC and if it's close I just go by computed average MPG.

vetteboy2k

iTrader: (5)

If you change injectors for a H/C swap you can throw the DIC MPG out the window. Way to many variables in the tune for it to be accurate, unless using Greg Banish's data for injectors to keep things in line.

As for the our current gas killing mileage, it does. Our fuels stoich is now around 14.1 instead of 14.7

Logging Fuel trims on a 800 mile trip I was averaging -2 LTFT everywhere, then filled up in NC that had no ethanol in the fuel and trims quickly went to -7LTFT everywhere. Proving you needed less gas than with the E10 fuel were given.

killernoodle

lol!!!

JNR_Design

iTrader: (3)

I understand what you're saying and it could be hard to be exact everytime, with regard to when it's actually "filled". I suppose if you always stop at the first 'click', it would be close enough, but yeah sometimes I notice the pump likes to click off prematurely, especially when cold. It's not so bad in the CTS, as it was in my GTO (2006), but I noticed you have to seat the nozzle in just right (more on the GTO) to get it to pump properly and full. Least that's how it is with our commi smog pumps here in CA, lol.

I like to use the electronic cpu reading for a good reference and notice it is relatively accurate when you're doing a steady, long drive. As for mpg logs, I rarely compute them since I hardly fill up, although been in a habit of writing my mileage down for the last 20+ years (why, who knows..one of those habit things, I suppose).

So, yeah, no argument here, just have to try and keep your fill-ups as consistent as possible and guess you could use both methods to get a good ballpark mpg.

Gus_Mahn

iTrader: (1)

In the last 13,000 miles my '05's never averaged better than 19.8 mpg just this week. 95% highway at 75 mph. Usually it's about 16 average in summer and low 15's in winter.

ColeGraham

iTrader: (8)

^^damn...on my last long distance roadtrip, Abilene, TX to Tracy, CA (1575 miles). i did 75 to 80 most of the way, with a couple pulls to 120. i went through 7000 feet of elevation change and ran with the A/C on 90% of the time. i was averaging 26.5 mpg there and 26.3 back.

the jester 812

iTrader: (5)

im with you, one time my friends wife saw that i was getting 24mpg hwy and said "wow that's horrible, shouldn't you be getting better than that?" her thinking was that it is a car, and in her mind a car is a car is a car. but i said, nope, this car has a 400hp corvette engine in it. 24mpg is damn good in my mind. i traded in my 2008 TBSS for this car, i went from high 13's to low 13's and from 16mpg hwy to 24mpg hwy. I get to row my own gears AND i now drive a caddy. doesnt get much better for me

bamacaddy

iTrader: (1)

I feel ya...I do hear people that say "If you've got a car like that you shouldn't have to worry about gas mileage." To an extent that is a valid point, but now these cars going in the mid teens, there are more budget minded drivers than there were when they were all owned by people that payed 50k +.....Now in saying that if MPG's were what I was concerned with "FIRST"...I wouldn't own a 400hp V8 car...I do average about 18.5 city and 24 hwy

mhhamrhead

iTrader: (4)

You want better mileage? Put 3.07's back in the rear.

Probably pick up a few on the highway. Maybe a bit more top end too.
Of course, it'll suuuuck off the line.


Unless someone wants to be the guinea pig and change out 5th and 6th gear ratios to taller ones? Not me.

ITSAV

iTrader: (1)

Ahh I wish I could shift below 2k, I am always working at keeping the car above 2k, below 2k is when my car makes that damn drone from the exhaust, if I could stop that from happening I'd def be below the 2k all the time lol

scatillac

iTrader: (12)

Even if you're far from stock, the DIC is still good as an indicator (during long trips on the highway) to keep your mileage up via monitoring for as high a figure as possible. Whether it's accurate or not doesn't really matter, it's the relevance that counts.

With all the fuel and air tables tuned for my combo, it's data is still useless for accurate fuel consumption predictions.

bbrown7888

I changed my oil and installed a K&N air filter. It's gone up to a steady 14.5MPG and the about 85% city driving in about 30 degree weather. K&N air filter is my only mod... if it is even considered one.

JJSimon904

iTrader: (8)

If I'm playing in the city it is below 10mpg. At 60mph I get 30mpg but usually average 15mpg to a tank unless I go on a trip or something. I could tune the car a bit leaner for better gas but like previously stated, I didnt buy this car to get good gas mileage.