Honda Car Forum

2000 Accord v6 suddenly went from 25 mgp city driving to 18 mpg. Any
ideas why?

On Wed, 14 Jan 2004 03:17:34 GMT, rml.ml@verizon.net wrote:

>
>2000 Accord v6 suddenly went from 25 mgp city driving to 18 mpg. Any
>ideas why?

In order of decreasing likelihood IMO:

1. tire pressure
2. cold weather
3. change in driving pattern
4. winter fuel formulation
5. brake dragging
6. problem with engine

Of course, it could be a combination of these. Note that 1, 2 and 4
are related to weather. (You can now tell me that you live in
Southern California.)

On Wed, 14 Jan 2004 03:17:34 GMT, rml.ml@verizon.net wrote:

>
>2000 Accord v6 suddenly went from 25 mgp city driving to 18 mpg. Any
>ideas why?

Winter. The engine runs on "choke" for longer. In severe cold your
engine's "normal" operating temp may also a be a few degrees lower than in
Summer so slightly less efficient.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

"George Macdonald" <fammacd@tellurian.com> writes:

> In severe cold your engine's "normal" operating temp may also be a
> few degrees lower than in Summer so slightly less efficient.

What??

I don't think so.

On Thu, 15 Jan 2004 05:59:52 GMT, "Chris Aseltine"
<ophidian@newsnation.com> wrote:

>"George Macdonald" <fammacd@tellurian.com> writes:
>
>> In severe cold your engine's "normal" operating temp may also be a
>> few degrees lower than in Summer so slightly less efficient.
>
>What??
>
>I don't think so.

If you can explain what it is you don't agree with I'll try to help.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

"George Macdonald" <fammacd=!SPAM^nothanks@tellurian.com> wrote in message
news:jklc005nmuqt1jn9pqm3li9np90jd5j4lc@4ax.com...
> On Thu, 15 Jan 2004 05:59:52 GMT, "Chris Aseltine"
> <ophidian@newsnation.com> wrote:
>
> >"George Macdonald" <fammacd@tellurian.com> writes:
> >
> >> In severe cold your engine's "normal" operating temp may also be a
> >> few degrees lower than in Summer so slightly less efficient.
> >
> >What??
> >
> >I don't think so.
>
> If you can explain what it is you don't agree with I'll try to help.

I know my car is running a little cooler these days...started up in five
seconds of cranking this morning, though, at -30C (-21F).

Shocks like rocks,
Seats like stones
Ride's so hard
I can feel it in my bones.

You're welcome. Coffee will kick in soon, don't worry...
Steve
Ottawa

"George Macdonald" <fammacd=!SPAM^nothanks@tellurian.com> writes:
> <ophidian@newsnation.com> wrote:
>> "George Macdonald" <fammacd@tellurian.com> writes:
>>
>>> In severe cold your engine's "normal" operating temp may also be a
>>> few degrees lower than in Summer so slightly less efficient.
>>
>> What??
>>
>> I don't think so.
>
> If you can explain what it is you don't agree with I'll try to help.

The point of a thermostat, which every car has, is to regulate the coolant
temperature regardless of engine heat output or ambient temperature. If the
air temperature is colder, that's just a little bit less open it will be, as
more heat is radiated away from the car per unit time (or volume of
coolant).

Empirically, I've never seen the temperature gauge in any car "level off" at
a different point in the summer versus winter.

"Chris Aseltine" <ophidian@newsnation.com> spake unto the masses in
news:s%pNb.55770$sv6.134490@attbi_s52:

> "George Macdonald" <fammacd@tellurian.com> writes:
>
>> In severe cold your engine's "normal" operating temp may also be a
>> few degrees lower than in Summer so slightly less efficient.
>
> What??
>
> I don't think so.
>
>


He's right. The block, head and rad lose heat much more rapidly in cold
weather. The greater the temperature difference, the greater the heat
transfer.

Basic physics.

--
TeGGeR®

On Fri, 16 Jan 2004 01:35:52 GMT, "Chris Aseltine"
<ophidian@newsnation.com> wrote:

>"George Macdonald" <fammacd=!SPAM^nothanks@tellurian.com> writes:
>> <ophidian@newsnation.com> wrote:
>>> "George Macdonald" <fammacd@tellurian.com> writes:
>>>
>>>> In severe cold your engine's "normal" operating temp may also be a
>>>> few degrees lower than in Summer so slightly less efficient.
>>>
>>> What??
>>>
>>> I don't think so.
>>
>> If you can explain what it is you don't agree with I'll try to help.
>
>The point of a thermostat, which every car has, is to regulate the coolant
>temperature regardless of engine heat output or ambient temperature. If the
>air temperature is colder, that's just a little bit less open it will be, as
>more heat is radiated away from the car per unit time (or volume of
>coolant).

After running your car for a good few miles in extreme cold, check your
radiator - it'll be stone cold and that cold air hits your engine straight
on. Add in the heater use and your thermostat will be closed most of the
time in extreme cold. Here's an experiment: with an ambient of say -10C
(not even that extreme), drive the car to warm the engine up and then let
it idle for 10mins or so, with the heater near high and the fan on position
2.

>Empirically, I've never seen the temperature gauge in any car "level off" at
>a different point in the summer versus winter.

The usual mfr installed engine temperature gauges are calibrated with a
plateau on the temperature curve - the needle will show the "normal" temp
over a temp range of ~10C around the "normal" engine operating temp.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

"George Macdonald" <fammacd@tellurian.com> writes:

> <ophidian@newsnation.com> wrote:
>
>> The point of a thermostat, which every car has, is to regulate the
>> coolant temperature regardless of engine heat output or ambient
>> temperature. If the air temperature is colder, that's just a little bit
>> less open it will be, as more heat is radiated away from the car per
>> unit time (or volume of coolant).
>
> After running your car for a good few miles in extreme cold, check your
> radiator - it'll be stone cold and that cold air hits your engine straight
> on. Add in the heater use and your thermostat will be closed most of the
> time in extreme cold.

I think it would have to be pretty darn cold that the thermostat would stay
entirely closed, and the cooling system wouldn't reach operating temperature
and would lose net heat under load. A lot colder than 0F or -10F.

> Here's an experiment: with an ambient of say -10C
> (not even that extreme), drive the car to warm the engine up and then let
> it idle for 10mins or so, with the heater near high and the fan on
> position 2.

When I had a '90 Grand Am a few years ago, it reached about -15F one day
during the winter, and yes, it did start to cool off at idle. I don't doubt
that this can happen, as I've seen it myself. However, once I started
driving again, the needle moved right back to where it usually rests.

That's the only time I've ever seen that happen. At 14F (which you're
giving as an example, with the heater on) I've never seen any car cool off
at idle.

>> Empirically, I've never seen the temperature gauge in any car "level
>> off" at a different point in the summer versus winter.
>
> The usual mfr installed engine temperature gauges are calibrated with a
> plateau on the temperature curve - the needle will show the "normal" temp
> over a temp range of ~10C around the "normal" engine operating temp.

Never heard of anything like this. This claim seems suspect to me. Got a
source/spec sheet or anything?