Monty

Okay some of you might rember my post about gears helping your topend instead of hurting it. (a couple of months ago). This post is kinda like that.

Everybody tells me that gears makes your engine rev higher (which is tru). and that since it is reving higher you are using more gas. BUT this is wut I was thinking. Lets say you have your car in netrual and give it 1/8 thortle. the car will rev and stay around 4 grand. But if your cruising down the road @ 20 MPHS and put the car in 5th and and floor it. The engine will stay at 2 to 3 grand. So going by the logic of gears makeing your mpg's suck. This would mean that you are wasting more gas at 1/8 thorttle than @ full throttle??? That dosent make sense to me.

Gears make it easeir for engine to turn right????.....So your not going to have push the pedal down as far to make it go. (which to me is directly relvant to how much gas you are using) just some thoughts.....let me know wuts up


MONTY

mdvaldosta

You are correct Monty in one respect, but missing another. The ECU sprays fuel based on a number of things, including engine rpm. Granted the engine can get the car moving easier (with less gas), the higher rpms will require more fuel to maintain. Driving around town this can be avoided - by using 4th & 5th gear when you would have been at 3rd or 4th with the stock gears.

So I tell people that driving around town gas mileage may very well increase, but on the interstate it will most certainly go down.

Monty

hm....... So your saying that the computer has set rpm to amount of fuel laws. Like....if rpms are X then fuel injected is Y???

This must only be under a constant throttle (like cruise control) right???? Because it won't work with a fluxuated(throttle). Unlees another one of those factors are the computer knowing wut gear your in and wut ring and pinoin you have. (and speed of vechile) right?

J/W
MONTY

mdvaldosta

It doesnt need gear your in, the ecu factors load in with the equation. The very basic injector pulse width formula factors in rpm vs load... after thats been calculated the ecu takes info from the O2 sensors, coolant temp sensor, etc.

Monty

OKay.... thats what I was thinking at first but couldnt figue out how it would detrmine load. So that why I went with the gear thing. How does it determine load???? j/w

cuz maybe you can find away to trick it and make it send more fuel......well that would make it run ****y instead of more power huh?


*edit* so this computer thing is always working wether its @ a constant throttle or fluxuateing? *edit*
MONTY