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Gro, i think there's one thing you're forgetting. Think about it like this: In winter you turn your AC off and you mileage is about the same as your summer mileage with the AC on 100% of the time, according to you. It's a proven fact that you wont get as much out of a tank of gas in the winter as you will in the summer. So your AC does affect your mileage, but you aren't noticing it because you're still able to travel the same distance. If you kept your AC off in summer you would probably see the difference.

I rarely use the ac, Im ikn west tezas and we are used to EXTREME heats.. now winder :S I do use the heater.. the defroster cylces the ac motor a couple of times. Its logical that the ac on burns more gas..when you are on the freeway its when its best to use it. The ac motor puts more strain on the engine. Have you notice when acceletaring and you turn the ac off you can feel the difference. Also try driving one day with the ac on all the time and clock your mines (try a day with little or no traffic) and then try anoither day without the ac. You defenetly will see a difference. I know ive seen it.

i'm confused how will keeping the car in gear save u gas

if ur driving around at 1rpm ur car will be burning less fuel as to u driving around at 3rpm ??

or does the fact that driving hard(at high rpm's) decreases ur fuel mileage not apply to this?

Flashpoint2 wrote:Gro, i think there's one thing you're forgetting. Think about it like this: In winter you turn your AC off and you mileage is about the same as your summer mileage with the AC on 100% of the time, according to you. It's a proven fact that you wont get as much out of a tank of gas in the winter as you will in the summer. So your AC does affect your mileage, but you aren't noticing it because you're still able to travel the same distance. If you kept your AC off in summer you would probably see the difference.

That is correct since its colder more gas is wasted since its denser air, but its pretty negligible.



But the thing is....last year my a/c worked, this year it doesn't (i bent a line & ruptured it this past winter when painting the engine bay). So yeah...my mileage is the same as it has always been and I haven't had the a/c on since it doesn't work. I really do think the power output of the motor & "available power" at a given RPM when crusing has a LOT to do with how much the a/c ruins your mileage.

Hoodzy wrote:i'm confused how will keeping the car in gear save u gas

if ur driving around at 1rpm ur car will be burning less fuel as to u driving around at 3rpm ??

or does the fact that driving hard(at high rpm's) decreases ur fuel mileage not apply to this?

No kidding, it doesn't make sence. Even if I'm coasting, I can't see the fuel being cut off, it probably inject the same fuel as when in idle, but it would do it more often because of the higher revs.

As for the RPM's when driving, it also depends on how hard the engine has to work. If your in 5th gear @ 2000rpm but to accelerate you need to increase the throttle to 80%, but if your in 4th gear @ say 4000rpms, you need to only push the throttle down to 40% to accelerate as fast as you would have in 5th...it comes down to how much work, the revs just say how fast the engine is turning, but it has no relation to how much fuel is actually being consumed to provide the power needed to work.

Gro Harlem wrote:That is correct since its colder more gas is wasted since its denser air, but its pretty negligible.

Wouldn't that be nul if you have a MAF instead of our car's VAF. A MAF (correct me if I'm wrong) is a Mass Air Flow sensor, this is "weighs" the air coming it, and should know if it's more dense. With that, if you have your throttle, say at 50% in both a cold winter and a hot summer, in the winter the computer will sence more air coming in, and should put in more fuel in relation to it, so yes, your fuel consumption would go in in that aspect, however, with more fuel and more air, you'll also get more power, thus not needing to use as much throttle to get the same amount of power/acceleration.

With a VAF sensor, with it sensing the volume, in the summer the car will run more rich (in comparison) in the summer and more lean (in comparison) in the winter. If my engine sucks in 2.5L of air, in the summer, because their air is hotter, it's molecules will be more spread out, and in the winter, because it's colder out, although i have 2.5L of air, the molecules are more tighly backed, so you have more air in the same space. If the fuel injection is constant; more air = leaner, less air = richer.

This is also affects engines at higher altitudes

i'm confused how will keeping the car in gear save u gas

if ur driving around at 1rpm ur car will be burning less fuel as to u driving around at 3rpm ??

or does the fact that driving hard(at high rpm's) decreases ur fuel mileage not apply to this?

Fuel injectors are an "on/off" thing. So when you are on the throttle, the injectors are "on", but if you take your foot off the throttle, your injectors shut off, as long as you are in gear. But if you take the car out of gear and coast, the car will have to use gas in order to keep the car idling.

Sorry to revive an old topic, but, are there any tricks that will make my car run lean with out an adjustable FPR?

Custom_V6_Limited_SE wrote:Sorry to revive an old topic, but, are there any tricks that will make my car run lean with out an adjustable FPR?

why would you want to run lean??? do you wanna melt the insde of your motor?

Bochek

How would running lean melt the motor? O, btw, I just had the funniest thing happen to me. I drove out of state to pick up and engine and other stuff with it and got 28mpg on the way to pick it up, but, on the way home, with ~400lbs. of stuff in the back, I got 34.2mpg. Is that insane or what? Could the 2 or 3 inches that it was lowered by the weight have affected the aerodynamics in a positive way? Or, was it definately some other unknown variable? Maybe whenever I'm going to be doing highway driving I should throw and engine in the back .

i want mine to run leaner..its to rich