how does having the "need gas" light on affect performance

[MilinGTS]

if i ran it at the track or dynod it with that light on, wopuld there be any difference?

[oldster]

I don't think so however continued use with the light on will lead to a dramatic drop in horsepower.........:rolleyes:

[redcellyinfl]

haha good one oldster...

[hollywood]

actual it might help you. no gas= no extra weight= faster track times.

[CeliRacer]

But imagine running down the track and halfway through the run, you run out of gas?

[Rog315]

that would suck!

[Chris25NJ]

i've always been told it's not good to run the tank that low, cause all the sediment from the bottom of the tank will run up into your fuel lines.......but I don't necessarily believe that.

[TRD-CELICA-GT02]

It's not good to run the car with that low of gas. You're basically running your car on the gas' vapors since the tank is near empty. so your engine is basically running off the fumes. I've been told that will harm your engine. Always have gas in there, avoid having the empty gas light on

[Griffin]

Originally posted by MilinGTS
if i ran it at the track or dynod it with that light on, wopuld there be any difference?

No - the ECM does not in any way shape or form monitor fuel level. So the light being on will not affect performace per se.

Griffin

[2002GT_Celica]

Usually, the lowest people let their gas tanks get before a track run is 1/4 of a tank left.

[SilverRide]

Actually sediment isn`t a problem as you`re constantly drawing gas fron the bottom of the tank anyway...full or near empty.

Runnining a low tank is a problem mainly in cold weather as is allows more space for (water) condensation to occure.

[StealthblkGTS]

It doesn't take a genius. For the life of the car, your safety, and to avoid running out, don't run on fumes. It's not even a racer's knowledge. If you drive you should know it's bad for your car.

[dx3162]

I've always been taught to run right around 1/4 tank. Also, i've heard that the more gas you have in the tank, the more steady the fuel pressure? Makes sense, but I highly doubt that you would run faster w/ a full tank, just because of the 110+lbs. of added weight.

[GTS LAID]

fuel pressure is regulated no matter what... if the hydrostatic pressure of the fuel in the tank is greater than what the pump needs then it simply does less work... but in any case the pressure through the lines will stay at whatever prescribed level the ECU assigns... unless you run out of gas.. in which you get the lean codes in the ECU.

[Maelfyn]

When the gas light comes on you aren't even close to being out of fuel. I'd say there's at least another 80 miles of driving left.

[Griffin]

Originally posted by GTS LAID
fuel pressure is regulated no matter what... if the hydrostatic pressure of the fuel in the tank is greater than what the pump needs then it simply does less work... but in any case the pressure through the lines will stay at whatever prescribed level the ECU assigns... unless you run out of gas.. in which you get the lean codes in the ECU.

Just wanted to point out that the ECU does not regulate fuel pressure. Pressure is regulated by a spring loaded bleed off pressure regulator valve in the tank - the spring tension is pre calibrated to maintain an exact level of fuel pressure. The ECM assumes that this pressure will always be accurate and makes its base fuel calculations accordingly. When the pressure drops below what the ECM assumes it will be the O2 sensor indicates the mix is getting lean and increases fuel trim to try and compensate. When the correction percentage exceeds 20% positive you will get a P0171 lean code.

BTW - 1 benefit to having your tank full is that it keeps the pump temperature down which in theory will improve the total durability of the pump.

Griffin

[pensfan83]

Originally posted by Maelfyn
When the gas light comes on you aren't even close to being out of fuel.

What he said. All this arguing is pointless unless you actually are at the point where you're running on the vapor. When my light comes on I've got about 2.4 gal. left, which is good for at least 48 miles. So you guys will have even more of a safe zone.