Gas mileage

Yeah yeah yeah, it's the topic du jour ...

How would I get better gas mileage. Should I let the engine idle for 3 -5
minutes, while waiting for a school bus, after driving 1/2 mile after a cold
start ?

I have an '06 Sienna. In the morning my commute begins by taking my 3rd
grade son to his bus top, 1/2 mile away. Then I take his 4 y.o. brother to
pre-school about 4 miles away. Then I drive about 10 miles to work.

I know about the cold start process of emission controls.

"Charles" <h90943@hotmail.commie> wrote in message
news:124j88j9pgp5d82@corp.supernews.com...[color=blue]
> Yeah yeah yeah, it's the topic du jour ...
>
> How would I get better gas mileage. Should I let the engine idle for 3 -5
> minutes, while waiting for a school bus, after driving 1/2 mile after a
> cold
> start ?[/color]

No. 1/2 mile is not long enough to get the engine, coolant, catalyst, and
O2 sensor up to operating temperature and shutting off the engine starts the
process over again.
[color=blue]
>
> I have an '06 Sienna. In the morning my commute begins by taking my 3rd
> grade son to his bus top, 1/2 mile away. Then I take his 4 y.o. brother to
> pre-school about 4 miles away. Then I drive about 10 miles to work.
>
> I know about the cold start process of emission controls.
>
>[/color]
--

Ray O
(correct punctuation to reply)

Your morning commute should be getting warmer by now, unless you live
up in mountains. Have you given any thought to using synthetic engine &
transmision fluids?
RH

I probably won't switch to synthetic. I run it in my 1.8liter Passat with a
Turbo. With oil change intervals at 3,300 miles I see no reason.

It would be a cold start even in the summer. According to Dennis Simanaitis
of Road & Track " ... with engine coolant at 200 degrees F , even a nice
ambient 80 degrees qualifies as a cold start". That is the emission system's
priority is to light off the catalyst to get emissions under control.
<rudyxhiebert@yahoo.com> wrote in message
news:1145756129.115973.102310@z34g2000cwc.googlegroups.com...[color=blue]
> Your morning commute should be getting warmer by now, unless you live
> up in mountains. Have you given any thought to using synthetic engine &
> transmision fluids?
> RH
>[/color]

"Charles" <h90943@hotmail.commie> asked:
[color=blue][color=green]
>> How would I get better gas mileage. Should I let the engine idle
>> for 3 -5 minutes, while waiting for a school bus, after driving
>> 1/2 mile after a cold start ?[/color][/color]


Ray O <rokigawa@tristarassociatesDOTcomn> responds:
[color=blue]
> No. 1/2 mile is not long enough to get the engine, coolant, catalyst,
> and O2 sensor up to operating temperature and shutting off the engine
> starts the process over again.[/color]


What does the catalyst have to do with this? Charles was asking about
improving his gas mileage, not about minimizing emissions.

Besides, if 1/2 mile of driving isn't enough to get the engine, coolant,
etc., warmed up, wouldn't letting the engine idle during his brief stops
be seen as desirable in that regard?



Geoff

--
"Support Darwinian evolution -- squash a weakling today."
-- David Wren-Hardin

"Geoff Miller" <geoffm@u1.netgate.net> wrote in message
news:e2gde6$dn4@u1.netgate.net...[color=blue]
>
>
> "Charles" <h90943@hotmail.commie> asked:
>[color=green][color=darkred]
>>> How would I get better gas mileage. Should I let the engine idle
>>> for 3 -5 minutes, while waiting for a school bus, after driving
>>> 1/2 mile after a cold start ?[/color][/color]
>
>
> Ray O <rokigawa@tristarassociatesDOTcomn> responds:
>[color=green]
>> No. 1/2 mile is not long enough to get the engine, coolant, catalyst,
>> and O2 sensor up to operating temperature and shutting off the engine
>> starts the process over again.[/color]
>
>
> What does the catalyst have to do with this? Charles was asking about
> improving his gas mileage, not about minimizing emissions.[/color]

You're correct - the catalyst does not have any effecd on fuel mileage.
[color=blue]
>
> Besides, if 1/2 mile of driving isn't enough to get the engine, coolant,
> etc., warmed up, wouldn't letting the engine idle during his brief stops
> be seen as desirable in that regard?
>
>
>
> Geoff
>[/color]

Oops! In re-reading my response to the original post, I realized that it
was not clear. My "no" response is to shutting off the engine, not letting
the engine idle. The OP should let the engine idle and continue to warm up
instead of shutting it down so early in the drive cycle.
--

Ray O
(correct punctuation to reply)