Ok, someone explain this to me (MPG)

[Redfireshaker06]

What mechanically would cause a car to have worse gas mileage? I was getting 19.x w/ 4.10's. I just had 3.73's installed (planning for blower), hit reset on the message center and 19.x still. Where am I having the hold back at?

 

[DKS]

What mechanically would cause a car to have worse gas mileage? I was getting 19.x w/ 4.10's. I just had 3.73's installed (planning for blower), hit reset on the message center and 19.x still. Where am I having the hold back at?

Right foot? lol

 

[bcb06gt]

4.10s will do better in the city and worse on the highway compared to 3.73s. So it depends on your driving mix and driving habits.

 

[Redfireshaker06]

This is only a highway calculation as of the trip home. Using the message center reading

 

[Redfireshaker06]

Oh sorry, the 19 reading w/ the 4.10's and 3.73's are highway

 

[JeremyH]

Message center is a guess at best. There are lots of other factors that go into actual gas mileage. Besides rpm at crusing speed.

 

[Redfireshaker06]

I disagree, its been very accurate for me

 

[JeremyH]

I disagree, its been very accurate for me

You can disagree all you want, its still a fact lol.

 

[Redfireshaker06]

I disagreed w/ your "guess at best" you added the rest after I was posting

 

[JeremyH]

If you have anything other than stock gears, stock tire height your message center is off. Calculate miles per tank and divide to get your average mpg.

 

[mrdeath2000]

yup, when i fill up, i divide my trip meter by the gallons it took for the pump to 'click' off.

~22mpg with about 70% highway 3.55's

 

[Redfireshaker06]

I know how to do it that way. But I was getting 23 mpg w/ the 4.10's and 20" wheels a few years ago. Now I don't even get 20 highway. Thats why I'm figuring its something mechanical

 

[gil_t2]

If you have anything other than stock gears, stock tire height your message center is off. Calculate miles per tank and divide to get your average mpg.

I hate to say this, but this is the first time, i disagree with Lightblade. I installed 4:10's and a 28 1/2 tall tire, added that info to my tune to adjust the speed-o. And my message center MPG is right on, and i confrim it the old school way.

 

[Redfireshaker06]

Thank you. Thats what I keep telling people

 

[BruceH]

One of the things used in calculation by the car computer is "pulses per gallon" It's a parameter available in prp. Once it has been calibrated it's damn close, like within .2 for me.

 

[Redfireshaker06]

IS there a way to actually clean our computer to relearn? Disconnecting the battery does not do it.

 

[God]

The problem with the pump-click-off method is you are assuming the tank is full each time when the pump clicks off. Different pumps may provide different levels of fill. The tank is never truly full (ie fuel spilling out the filler) when the pump clicks off, and you can usually add more by squeezing the pump lever some more.

What you really need to know is exactly how much fuel was actually consumed over your trip mileage, and that is difficult to do using a refill measurement method, unless you fill the tank repeatedly to the point when the fuel starts to spill out.

The PCM has a PID called FLI, or Fuel Level Indicator. This PID reports the percentage of fuel remaining in the tank to two decimal places, ie 73.28%. This fuel level accuracy combined with the PCM's knowledge of exactly how many miles were traveled should provide for a more accurate calculation than trying to calculate it manually. Can anyone explain why it wouldn't?

 

[mrdeath2000]

neighbor stealing your gas?

i'd use the message center, but i dont have it, so I old school it. however, if he is concerned with the mileage, see what the manual method provides just for extra data.

 

[Redfireshaker06]

I know its accurate because it usually takes pretty damn close to the gallons used to fill up. Only thing I have not changed yet is the plugs.

The thing I can't figure out is. When I hit reset, it never even goes high and works its way down. It usually never goes over 20 mpg. Which is wierd

 

[gil_t2]

The problem with the pump-click-off method is you are assuming the tank is full each time when the pump clicks off. Different pumps may provide different levels of fill. The tank is never truly full (ie fuel spilling out the filler) when the pump clicks off, and you can usually add more by squeezing the pump lever some more.


That is why i use the same gas station and the same pump. That way the car is parked at the same angle. The pump shuts off when the gas hits the nossle air tube, or vapor vac