I have always gotten bad gas mileage from day 1 with my car, on my stock DX motor got about 200-250KM's to a full tank, I got my LS and that didnt change, now all of a sudden I filled up on gas I've drvin the car maybe 20-40km's and I'm down to half full. I'm think a leak somewhere? And since my swap I have not changed plugs or anything like that.

 

Clogged air filter
Clogged injectors
bad O2 sensors
bad spark plugs
bad spark plug wires
bad distributor cap
poor ingnition timing
aggressive driving

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Spade &raquo;</TD></TR><TR><TD CLASS="quote">
aggressive driving

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<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99blackcivicSi &raquo;</TD></TR><TR><TD CLASS="quote">

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lol. i drive aggressive everywhere and I'll still get 250-300 miles a tank.

 

On this tank I dint drive hard at all, I was only driving to school and work, plus its very slick out on the roads, so even if I wanted to I can't get any traction.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MrIllegalX &raquo;</TD></TR><TR><TD CLASS="quote">

lol. i drive aggressive everywhere and I'll still get 250-300 miles a tank. </TD></TR></TABLE>

Hell, I boost everywhere and can still get 330 or 340 a tank.

 

Try seeing if the fuel level sensor is out...Maybe you are still getting the same mileage but your sending unit isnt reading the fuel level correctly

 

do you smell fuel anywhere at all? maybe you have a fuel leak somewhere. what's your fuel pressure set at? upgraded ecu?

when i had a stock LS in my 94 SI, i was able to drive from st.paul all the way past Madison, WI on one tank of gas. about 4+hours of driving.

 

honestly, you can't burn gas THAT fast... the exhaust would be pitch black, so if you are, check the exhaust.

I'd bet it's the sensor or the fuel gague itself perhaps.

 

if your car was getting 40mpg to a half tank , i dont think the car would run off that much gas , has to be a leak

 

ont smell any gas, nor is there any on the ground.
Stock ECU, stock fuel pressure. everyhting is stock right now, except i/e

 

tire pressure is a big factor when determining gas mileage.

Check your tires and see what psi you are running.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sassafrass &raquo;</TD></TR><TR><TD CLASS="quote">ont smell any gas, nor is there any on the ground.
Stock ECU, stock fuel pressure. everyhting is stock right now, except i/e</TD></TR></TABLE>

you won't be able to see any gas on the ground if it's leaking. it evaporates almost instantly if in small quantities.

it's odd that you would lose so much gas...do you have any CELs? check to see if your CEL bulb is working. maybe you've got a bad O2 or something and running in limp mode? sorry for the guesses but just trying to help.