Hi all

I'm a piano tuner that spends a good amount of time in the box - I've read on the forums for awhile, but this is my first post.

I've read with interest the threads on increasing mpg - especially the recommendation to coast in gear to reduce fuel use to zero, as opposed to coasting in neutral.

I'm hoping to get a scangauge of my own soon, but could someone with an auto trans and a scangauge check this out for sure? Is it better to coast on those long exit ramps in neutral, or take my foot off the gas, or keep the foot on the gas to make it a no-load situation. (that last one comes from a Prius owner...)

Thanks!

 

no, it is not better to coast in neutral. when you coast in gear with your foot off the gas, the ecu cuts fuel to the engine, and the car engine breaks with the momentum still spinning the engine and slowing the car down and keeping it under control.

when you coast in neutral, your rpms drop to idle level, BUT your engine has to supply fuel to the engine to keep it idling, so you are using more fuel than coasting in gear.

 

Is that true for the auto trans as well?

I've removed the snorkel and just put in denso iridiums, but I struggle to get over 30mpg with the gas that is available in Chicago. It was trending around 27-28 mpg or so over the winter before the plugs change. Last fillup just a bit over 30mpg...

I'll wait and see what I get when it finally gets a little warmer around here!

 

winter gas is no good, ive always had bag mpg during winter time.

tried resetting the ecu since youve switched the plugs/taken off the snorkle?

 

30 MPG is the old EPA city rating. If you're getting it, then you're good. Using the revised rating for an auto xB it is 26/30 and more realistic.

http://www.fueleconomy.gov/feg/calcu...umn=1&id=22127

 

If you're really ambitious, you can coast in neutral with the engine off-- that's definitely using zero fuel. Of course, I'd only recommend it in situations where you won't get in anyone's way. For example, I take some backroads to work, and can coast a good half a mile (more if not for a small hill in the way), and if there's no one behind me, as is the case most mornings, I just shut my car off.

Of course, if you really meant business, you could hypermile: http://www.ecomodder.com
Those guys take things to a ludicrous extreme, but you can learn a lot there.

 

that is the worst idea...EVER, i mean seriously. turn off the engine, say bye bye to your power steering, and then, your brakes. your brakes are vacuum powered by your engine, in the tc, it says that should the engine fail, there is enough vacuum power stored to push the brake pedal down a total of 3 times, but i'm not sure about the xb/xa, but yeah, don't even think about doing something that stupid ever again.

oh, and turning your engine off and on and off again to save gas, your saving that money to buy yourself a new starter for your engine because that will will real tired of that routine really fast.

 

I did reset the ECU after the snorkel, but not the plugs.

Hmmmm...

 

Sometimes I wonder about this. I am sure the fuel shut-off is true for SOME cars while coasting in Drive, but I'm not sure about the Scion.

I my own real world tests on hills while coasting both in drive and in neutral, (and keep in mind I live in Pittsburgh, one of the hilliest cities besides San Fransisco where here you are always either going up or down a hill and straight flat roads are rare), I found if I coast down a hill in Drive, I only go so far up the other side before I have to put my foot on the gas again, BUT if I coast in neutral, I can make it up the other side much farther before I have to put it back in drive and gas it.

So, my little brain has many thing to ponder before I make a decision on which is better. To coast in Drive or neutral ????

 

well, they said that on top gear, so it therefore must be absolutely 100% true. and yeah, i've visited family in pittsburgh, i bet that place is the biggest consumer of brake pads on the east coast.

 

It's normal that car comsumes more gas in winter.

Cold air=denser = leaner A/F ratio causes ECU to add more fuel.


The engine comsume much gas on idle.
Even for automatics, ECU cuts off the fuel with gas pedal off.

 

That, and winter gasoline formulations tend to simply not burn as efficiently, in the name of lower emissions (i.e., so that exhaust doesn't accumulate as as much in snow and such, thus mitigating a major surge of pollution whenever there's a thaw).

 

well, they said that on top gear, so it therefore must be absolutely 100% true. and yeah, i've visited family in pittsburgh, i bet that place is the biggest consumer of brake pads on the east coast.[/quote]

Yeah, must be true if it was said on Top Gear!!

Yeah you are right about the brake pad life here. I just posted on the other thread that I was way more than half gone on my pads at 28,500 miles. In fact I need to change them soon.

But back to fuel system shut-off at coast in Drive.

Last night going home while coasting down one of many hills on the way home (in Drive), and coming up to the stop signs at the bottom of the hill, I noticed that when I come to a complete stop after coasting, it is impossible to tell when my fuel system starts suppling fuel again because my engine is idling normally when I stop. It is completely seamless and unnoticeable.

What and where does the computer or the fuel system get it's input to know that there is a stop at the bottom of the hill to turn back on my engine so it is idling when I stop?? Is it speed ? Is it the brake pedal ? Man, you really have hurt my brain thinking about all this !!

I think back to my motorcycle, minibike days when the engine would die while at speed. Suddenly with a bang the engine would explode back to life when you finally figured out you accidently hit the kill switch or shut off the fuel like an idiot. That doesn't happen on my car.

Are modern fuel systems that advanced? Me thinks it might be a combination of the two. Sometimes under the right situation the fuel might shut off, but most of the time coasting in drive the system is probably still suppling idle fuel amount. But doing 65 mph in drive with your foot off the gas probably pegs out the scan gauge.

The debate goes on, but now I have to have a drink !!![/list][/i]

 

My mileage has dropped from 35 last summer and fall to 30-32 during winter. I look for it to pop back up soon when the temps are higher and the winter gas is gone.

 

I have an auto and a Scangauge...
When you lift off the gas the deceleration fuel cut off kicks in (or off?) and kills the fuel until the RPM's hit about 1100 then the gas is returned to keep an idle. So on a long downhill on say the freeway if I lift the MPG shoot up to 9999 and my wideband blanks out...not bad!

 

At what speed do you get the most mpg?

 

Considering the auto's are a 4-speed , it would be optimal to be crusing at about 40-45mph .... and at that speed you should be in 4th gear. I'd think that would be a very optimal range to be at( on flat, or slightly hilly terrain).

However, not just xB owners, but also xA owners have reported excellent MPG when in 5th gear going 65-75mph on fairly long straches when the rpm's are up around 3100-3400 , getting 40-45 mpg.

Is it alright for a auto owner to be in drive , then to switch to neutral for a little bit of time , then to kick it back into drive when needing to accellerate ???? I'd think if anything it would put more strain on your tranny by doing so .... not to mention while your in neutral like others have said, you'll be eating more gas then by keeping it in gear.