Any damage to auto transmission when coasting in Neutral

[MARTINSR]

Originally Posted by PaleMelanesian

You really need some kind of MPG gauge to know whether it's working or not.

I have TWO gauges that tell me, the odometer and the gas gauge.

Listen, of course if you are shooting for the ultimate MPH, if you are a hypermiler Extra Large and want to squeeze every table spoon out, then you are correct. But when I simply fill up the tank and look at the odometer the next fill up and the EXACT amount of miles are there, that isn't doing ME any good.

Studying the suggestions on this forum and practicing them has helped me a LOT. I have done a number of tests and found that "normal" driving was costing me about three miles to the gallon. That isn't crazy dumb ars driving which would cost you even more. Just "normal" accelerating up to lights and crap like that. That means that with some simple hypermiling I am able to get four days of driving to work FREE. This is without putting it in neutral, simply taking my frigging foot off the friggin gas. It's amazing how much that will do, like they old comedy routine about the single mom with six kids. It's rated R so I can't say it by you may have an idea, "just put it down" the guy said. I just simply take my foot off the friggin throttle more than I put it on, and it works great.

Now, the putting it in neutral IS amazing in how far that damn car will roll! It is absolutely amazing how far it will roll! But in super anal hypermiling with my head all full of timing signal lights and anticipating other drivers movements and the like, I didn't see a "measurable" difference from simply taking my foot off the friggin throttle!

I have also done an little time study on my daily commute that is eye opening to the anti-hypermiler.

After taking a co-worker to pickup a customers car and having him crying and moaning about how much time we were taking because of my hypermiling I started a log on how much time it took me to drive to work hypermiling verse driving normal. On an average it saved NOTHING to drive faster! Literally within error (2 tenths of a minute, 12 seconds!)

And once again, I have proven you can't drive faster than traffic, it is a feels good myth.

Sooooooo, once again, I'll be coasting in neutral with my other car that has a manual trans, I will be doing plenty of testing with it as well, but coasting isn't going to hurt it one bit.

On my SHO, I got pretty good at it in knowing when I could put it back in drive where you didn't even feel it. I did it a LOT, and got good. But still felt that it's gain was far too small for it's possible cost. The transmission is just not designed to do this.

The engine speed drops almost 400 RPM with it in neutral so you would think there is going to be a big difference, but I just didn't see it. I assume that even though the RPM may be at 1200 vs 800 in neutral there is no load so the computer isn't adding fuel? I mean, in todays cars with the computer managed motor it is pretty hard to outsmart it.

Brian

[PaleMelanesian]

I mean a real-time gauge. Unless you can tell whether that last quarter mile helped or hurt your mileage, you're just shooting in the dark. When I got my Scangauge, the very next tank's mileage was a new record by 10%.

Rolling in gear but off the gas... It may be shutting off the fuel, but you're getting a lot of engine braking. That costs you fuel to get back to speed later.

I recently did a 1200-mile highway trip in the Odyssey van, rated 16/23. Thanks in part to strategic neutral coasting, I got 31 mpg for that trip. The neutral coasting, I estimate, was worth about 2 mpg of that.

[MARTINSR]

Originally Posted by PaleMelanesian

I mean a real-time gauge.

I knew what you meant, I was just being a smart ars. I understand it could be a little more, but with my simple old fashion MPG figuring it wasn't worth it.

Not for what that tranny costs on my 15 year old car.

Brian

[TheMarkofPolo]

When did DFCO become popular? Would that Saturn have it?

I found that my 2007 Pontiac Vibe has it. It kicks in at speeds over 35-40mph when the engine is warmed up. Because my automatic isn't tow-flat friendly, I really shouldn't turn my car off in neutral.

However, I'm trying to observe what happens when I focus on utilizing the DFCO to its fullest versus throwing it in neutral (engine on) during coasting. The ScanGauge and my fuel log are so far indicating that focusing on the DFCO benefit in an automatic Vibe is worth it.
Long live my transmission!

[99LeCouch]

The transmission on the Buick will kick out of TCC lockup when I neutral-coasted on the highway. So I stopped, to prevent the TCC lockup solenoid from frying. The transmission will let the car coast for forever anyhow. The owners manual says not to flat-tow the car, so I stopped neutral-coasting the Buick. No DFCO either, just the engine goes to near-idle levels of fuel injected, like 0.50 GPH of fuel. Warm idle is 0.40 GPH.

The Honda Fit I drive occasionally will gladly EOC, and is flat-towable. DFCO is useful on the hills around here.

[soubi7string]

is a 92 oldsmobile cutlass ciera s safe to coast in N then shift back into drive?

[postmac]

TheMarkofPolo,
any more updates of your mpg utilizing DFCO in the Vibe? Don't have a scangauge but recently bought an 06 vibe automatic. My average mpg is about the same as yours right now.

[TheMarkofPolo]

postmac,

Wow, what are you doing? Some of those numbers in your fuel log are great.
My numbers are great unless I hit traffic (wrong time of day), or get in a hurry on various road trips. I've also blocked my upper grille (gee, thanks Pontiac)...getting ready to cover the undercarriage space at the front of the car when it gets cooler.

As far as DFCO goes, I'm still using it as much as possible. Once the car warms up, it works from about 35-65mph. If I coast at those speeds, GPH drops to 0. Lowest engine load is 6 or 7 at about 57mph (a good speed at which to drive or coast, anyway). However, I think I'm going to return to doing Neutral (engine on) at lower speeds or to a stop. GPH maintains about .3 coasting to a stop or in neutral, but distance increases in N, obviously.

[postmac]

The mid 40's mpg may be due to gas station pump cutoff variances. One was only a couple gallon fill up when I was trying to get good gas mileage, but I think actual mpg was not that good.
Tires at 44 psi, max highway speed 55 mph, keeping shift point at 2000 rpm.
Thanks for the scangauge reading info. Was wondering optimal speed and fuel usage while coasting.

[postmac]

Does this sound accurate?
If I take any coasting speed (35 to 0) and divide it by your .3 g/hr rating, I will get the instantaneous mpg. So 35mph/.3 = 117 mpg, and 15/.3=50mpg. Using this I find that I should only try to coast down to about 11 mph if I want better than 36mph average.

mph mpg
2 7
3 10
4 13
5 17
6 20
7 23
8 27
9 30
10 33
11 37
12 40
13 43
14 47
15 50
16 53
17 57
18 60
19 63
20 67
21 70
22 73
23 77
24 80
25 83
26 87
27 90
28 93