Coasting in Neutral???

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Tegger wrote:


not true - and we've had this conversation before. the porsche type synchro is a large annular ring with a couple of springs inside. it has steel-to-steel contact, unlike the bronze cones of the more traditional type.

not so. the porsche type is simply a friction fit. if you want to race it and over-ride the blocking action, you can.

while they spin, they're hydrodynamically separated by oil.

actually, all it means is that the two are in sync. nothing else. it won't drop in [under normal usage] unless they are. if it takes time to sync, it doesn't matter because the real syncing comes from rev matching if relatively low mass components - two cogs, two shafts and a clutch friction plate.

not so you'd notice. really, the blocker mechanism is excellent and lasts as long as the rest of the transmission unless forced. and that includes defective clutch and/or over-zealous shifting. my crx had 306k miles on it and the synchros were perfect - no crunchiness at any speed, in any gear.
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Then Honda synchros are cones. We're talking Hondas here, not Porsches.
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Tegger

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On Wed, 02 Jul 2008 14:34:44 -0700, googamooga wrote:

Others have explained the wearing out stuff... Bottom line is, coasting is a waste of time, won't really give you any benefit, and might actually cause harm. Just drive along like the rest of us.
--
"Bother!" said Pooh, as Rabbit pushed him off the speeding train.


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Dan C wrote:

the engine is rotating, but that's because the momentum of the car is pushing it. all the pistons are doing is pumping air - the injectors are not releasing gas unless the ecu says to do so. and in this situation it doesn't. when the revs drop below threshold again, /then/ it starts to inject, and thus the engine can run on its own. the transition is seamless and the driver never notices.

nope, it's completely different.
go to megasquirt.info and read through the source code for an injection computer. all the modules are easy to follow and you'll find the section where it specifically states the condition for over-run fuel cut off. enjoy!
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They've really screwed down the fuel-cutoff since 1995. All Honda engines now shut off the injectors on decel at or below 1,000 rpm. There's one Civic engine where they shut off on decel above 850rpm. Can't remember which one just now, though...
In 1991 it was 1,500 rpm.
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Tegger wrote:

sure. absolutely no point injecting if the momentum of the car is still turning the motor.
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wrote:

Interesting. One change I noticed in my 2007 Accord 4 auto over the 2004 is that with foot off gas it almost seems to decelerate like an old-style drive-by-linkage manual!
On the other side, I notice GM is advertising a car that (apparently) shifts to neutral while waiting at a light. Oh, technology! I often do that myself when I catch a long cycle, can be two minutes at some major intersections. I just get tired of standing on the brake that long, besides saving a few drops of gas.
J.
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