qestion on driving a manual

[Christopherrr]

which would be the better fuel saving method...granted my TA and auto...but just curious.

a. your going up hill and need to speed up, your in 6th gear and you give it gas, almost WOT.

b. your going up hill and need to speed up, you drop it in 4th and engine RMP rises and you press the accelerator a lil to get going.

my question is, if you leave it in 6th and give it WOT more air is being mixed with Fuel that = more fuel consumption right? Now if you grab a lower gear the engine revs, you give it a lil gas, but since you're in a lower gear engine rpm is higher and engine is feeding more gas that too = more fuel consumption...so what's what? How would you figure out somein like this.

no need for an answer...just been bugging for the past month.

[Injuneer]

The engine will use only the air it needs. If you're lugging it at 1500rpm in 6th gear, you floor it an not much happens. The MAF sensor reads the airflow, and adds the right amount of fuel. Where you can waste fuel is the way the computer richens the mixture to provide more power. The computer looks at the rpm and the intake manifold pressure (MAP) and the rate at which the throttle is moving. Then it richens up the mixture, the way the "accelerator valve" used to do on a carburetor. You really don't want to leave it in 6th gear, because it would be possible to richen things up and pour too much fuel in the cylinders and wash the oil off the walls. You also increase the chances of "detonation".... .developing a second flame front in the cylinder from the excess pressure and temperature, and forcing the computer to retard timing.... lower power, higher fuel consumption.

Its probably better to drop down one gear, and push the RPM up to the 2,000 range. By moving the throttle less, you cause less "power enrichment", so the net will probably be less fuel use and less stess on the engine.

[Jay 02 TA ws6]

Wow, thanks Fred. I had always wondered that myself. Especially as a college kid always trying to save gas

[Christopherrr]

as my science teacher told me long ago..."don't be afraid to ask a question, because there is someone probably wanting to ask the samething"