Urgent Help 8MPG 03 V8

[TURBOSPEED]

im having extremely bad mpg in my 03 LS V8 , im getting from 9 to 8mpg , already changed air filter , fuel filter (twice ) plugs , tried both regular and premium gas , already cleaned the maf and disconeccted the battery , checked psi in all tires.

99k miles , dont know if coils have already been replaced im going to the states to check then this tuesday.


i do get tranny slip when the car is cold and i inmediatly put it in drive , if i warm it up 20-30 seconds it works perfectly , also if get a sligth clunk when i put in reverse.

i do use AC most of the time but even with the ac off i get maybe 9.5-10MPG.


in highway i get 19-20mpg sometimes even 24.

 

[mrfuzz]

Change your driving habits around town =)

 

[King03LS8]

Yeah...no joke.

I get 18-19 in the city with my LS.

You might have several bad coils as well.

 

[gcwimmer]

Shift it out of 1st.

Make sure your family or neighbors are not stealing gas.

 

[97stscaddy]

I drive like a bat outta hell most of the time and I still manage to get 12 or better from most fill ups.

Ill give you one piece of advice though, Do NOT run regular gas in your LS. It was not designed to run on regular and you can cause irrepairable damage to the engine if you continue to do so.

You've also made it to the recommended mileage where your plugs need to be changed, if you haven't done so already.

 

[NateRW21]

99k mi? Changed the plugs yet?

But yes... looks like your city driving habits are very "16-ish" (teenager/child/kid with a toy-like)

 

[lincoln00]

stop using D4 in town use only D5 for everything if you are trying to get good mileage

 

[BrklynExpress]

In the summer, in 5-15mph stop and go traffic, at 90 degrees, AC on max blast, I dropped down to 9 mpg. I got the 30K service done (Car had 37K miles when I got it in July). In the same exact conditions I got 11 mpg. I have hit as low as 23 on the highway with no AC at 60 mph, and as high as 30.2 at 57 mph.

Bottom line, do your scheduled maintenance and don't use anything lower than 91 octane. If theres 89 or 93 available, go for 93. Don't skimp on it because your mpgs go down

 

[TURBOSPEED]

i been driving it like a baby and i still dont get over 10mpg, im thinking maybe 02's or clogged cats. also im going to get the coils checked.

 

[SPSully]

holy crap!!!!!!!! I get better milage than that at the track!

 

[02LSE96LSC91SE84TC]

I haven't seen less than 18 since like forever and I beat it daily. 20s on and 4.10 gears. Get 20-21 on stockers average and more when busy at work/ more highway.


You may want to manually check it. Thats like 100miles before the message center is going to tell you 50miles to go. Hard to believe.