City Driving is Killng my FE

[MetroMPG]

Originally Posted by rh77

So can I turn the ingnition to "engine off" then back to "on" without freaking out the ScanGauge?

only one way to find out! and you won't freak it out. depending on the car's ODB protocol, it will either go to sleep and take 10-20 seconds to re-initialize when you switch the key back on (during which time fuel, speed & distance data isn't logged), or it will remain on processing merrily away.

Is there a secret to acceleration from a standing start? With the automatic I'm trying to decide if slowly accelerating is more efficient than a little more quickly getting up to a powerful rpm

1 - if i had to use a/c (don't have it in my car), i would manually switch it off when accelerating, and switch it back on only when cruising or decelerating. (my car's "a/c" is a wood bead seat cover. keeps the air flowing behind and beneath, and no sticking to the seat.)

2 - as for rate of acceleration, my recent 80+ mpg segments have been achieved with the *slowest* practical rate. though i haven't done any tests to see if quicker is better.

though it stands to reason that quicker would only be better if your cruising speed is going to last for a long time. if there's a stop in your near future, you won't reap the hypothetical benefit of quicker acceleration because your cruise/coast won't last long enough to make up the difference.

To answer JanGeo's question, the car gets much better mileage in D when the engine is on for decel -- N forces more fuel to maintain idle.

that may be, but the next big question is which decel technique, D or N, yields the longest coasting distance?

my car's injectors shut off when decelerating in gear, but it's a fact that coasting in neutral with the engine idling is far more efficient because the car goes *significantly* further decelerating in neutral than decelerating in gear.

ymmv. that's why you have a scangauge!

[rh77]

Originally Posted by MetroMPG

that may be, but the next big question is which decel technique, D or N, yields the longest coasting distance?

my car's injectors shut off when decelerating in gear, but it's a fact that coasting in neutral with the engine idling is far more efficient because the car goes *significantly* further decelerating in neutral than decelerating in gear.

ymmv. that's why you have a scangauge!

[/quote]

This is how the ScanGauge rates as one of the best inventions of all time: 1. Sliced Bread, 2. Eli Whitney's Cotton Gin, 3. ScanGuage. This thing is awesome. I already have a friend buying one to monitor his MPGs.

Now, the N or D question has been considered. For my ECU, long grades would easily be engine shut-down + N or engine-on + D -- not a whole lot of compression holding back. Short-distance would have to be engine on for me with the auto. There's a significant loss in FE when I coast, in N, with the engine-on. D seems to yield a better benefit. Engine off showed 9999 mpg, which is as good as it gets on the device (flipping back to ingnition "On") keeps it alive. I just have to weigh the FE vs. starter wear. Too bad there's no way to kick-start an automatic or else I'd be coasting all over the place.

Let's get crazy folks...since the rear wheel is on an independent suspension, a half-shaft and CV setup would be way too complicated to have an electric motor as a movement assist. Picture a swing-arm mechanism on a shock absorber and gear-drive attached to a small rubber tire and an electric motor that could be moved to meet up with the car's rear tire at a stop. When you need to go, then engage the electric motor (probably need some serious batts in the back (weight :-( ), then after the car is started and put into D, the swing arm is activated to move the drive tire away from the car's tire.(perhaps automatically). At higher speeds, the arm could be moved manually so the little tire meets back with rear tire and the motor could be switched to a generator to charge the batts, completely independent of the alternator. Of course with suspension movement, it would have to be robust and shock absorbing.

1. I wonder if there's enough room back there for such an apparatus.
2. What kind of motor and current is required?
3. Would the rubber drive tire have enough rubber-on-rubber traction to achieve movement with the car's rear tire (rain or water would probably render the idea moot)?
4. Am I crazy?

Feel free to answer all questions, including #4.

RH77

[Compaq888]

#4 seems about right. Don't spend a lot of money on stuff to increase mpg by 2-3.

[SVOboy]

Damnit, so I should stop coasting to a stop in neutral, damnit!

Thanks for that.

Anyway, once I killed the car and left it in drive, about as fast as I killed it it started back up. Ooooppps.

[rh77]

Originally Posted by SVOboy

Damnit, so I should stop coasting to a stop in neutral, damnit!

Thanks for that.

Anyway, once I killed the car and left it in drive, about as fast as I killed it it started back up. Ooooppps.

Not sure what your injectors do on low-speed decel (with OBD-I), but for me, they tend to cycle down when when I coast in drive. At N, the MPG goes down around 50mpg from 150mpg to 100 or so. It takes more energy (fuel) to idle the car than it does to use the energy of momentum to slow you and use it to turn the engine. Since your car is very light, you're mileage may vary.

RH77

[MetroMPG]

Originally Posted by rh77

I just have to weigh the FE vs. starter wear. Too bad there's no way to kick-start an automatic or else I'd be coasting all over the place.

when was the last time you had to replace a starter motor on ANY car?

for me it was probably 16 years ago on a vw rabbit. i think i changed 2 or 3 rabbit starters, which says something about rabbit starters vs the rest of the world (i owned a small herd of rabbits when i was in h.s./university). other than that, i've never changed any other car's starter, and i've probably owned around 20 different old, beat up, used cars.

even if you did have to change a starter, aren't they a dime a dozen for that engine? from all the swapping going on , i'd think in the unlikely event you wore it out, you could get a replacement pretty cheap.

i say: live a little. coast! all over the place.

[SVOboy]

His engine, actually, is very desirable, so it might not be the easiest thing to pick up. His tranny sorta sucks, but never the less, it's tough to get at too cheaply. I'd have trouble finding a free one (I have two free starters for my car, )

[rh77]

Originally Posted by SVOboy

His engine, actually, is very desirable, so it might not be the easiest thing to pick up. His tranny sorta sucks, but never the less, it's tough to get at too cheaply. I'd have trouble finding a free one (I have two free starters for my car, )

That should be a pretty good pick-up line. "Hey, you know I have a desirable engine :wink:"

SVOboy you're right, though. The starter may be robust, but the transmission is what it is. When it goes out a 5-speed's going in there, but that'll even probably be a while. I have heard of Toyota starters going out often, but not Hondacuras.

Originally Posted by MetroMPG

i say: live a little. coast! all over the place.

I don't know if they still make it, but do you remember that Coast soap? They had a catchy theme song about it waking you up and getting you going in the morning. That's what will solve the gas problem:

A national advertising campaign:

to music: "Coast! It will save you gas. Coast! Now Exxon's kissing your ***..."

RH77

[philmcneal]

here's something to think about

60 km/h in N = 110 mpg
50 km/h = 90 mpg
40 km/h = 70 mpg
30 km/h = 50 mpg
20 km/h = 30 mpg
10 km/h = 20 mpg

any speed = engine off 9999999999 mpg

my engine displacement is 1.7 liters by the way.

[krousdb]

Originally Posted by philmcneal

my engine displacement is 1.7 liters by the way.

Sorry to hear that Phil. You are not alone. I am stuck with my 1.5L fat pig of an engine. Id be happy with a 3 cyl 1.0L.