E90 difference in gauges?

I recently took a look at the 328i and 335i E90 sedans.
On the 335, it looked like the MPG gauge was not there.
On the 328i, there was no temperature gauge.

Why the difference between the two?

Anoop

"anoop" > wrote in message
oups.com...
>I recently took a look at the 328i and 335i E90 sedans.
> On the 335, it looked like the MPG gauge was not there.
> On the 328i, there was no temperature gauge.
>
> Why the difference between the two?
>
> Anoop
>
Isn't the mpg gauges nothing more than an estimate based on engine vacuum?
If so, there is no vacuum in a turbocharged engine to measure; hence the mpg
gauge is useless. In contrast, it is nearly useless for the normally
aspirated
engines.

As for the temperature gauge, it is also useless because all it really shows
is that
the engine is either cold or not.

Jim

"Jim" > wrote in message
. net...
>
> "anoop" > wrote in message
> oups.com...
>>I recently took a look at the 328i and 335i E90 sedans.
>> On the 335, it looked like the MPG gauge was not there.
>> On the 328i, there was no temperature gauge.
>>
>> Why the difference between the two?
>>
>> Anoop
>>
> Isn't the mpg gauges nothing more than an estimate based on engine vacuum?
> If so, there is no vacuum in a turbocharged engine to measure; hence the
> mpg
> gauge is useless. In contrast, it is nearly useless for the normally
> aspirated
> engines.
>
> As for the temperature gauge, it is also useless because all it really
> shows is that
> the engine is either cold or not.
>


The MPG guage LOOKS like it is vacuum operated, but in reality is is a
display of the injector timing compared against the vehicle speed. If you
roll down the road at 40 and take your foot off the gas, the injector timing
becomes very short, so the amount of fuel needed to continue on this kind of
operational profile would be very small, and the MPG would become very
high -- on my car (an E36), this is full scale for Best MPG. As you continue
rolling along and approach a stop, the guage begins to drop because at the
given speed and injector timing, the vehicle cannot continue at the Best
MPG, and at full stop it gets the Worst MPG. On my daughter's E46, the guage
works the same, except that when the car gets to a full stop, the guage goes
to full scale Best MPG. I can't explain why it would do this, but my
inclination is that there is a software bug.

In any case, I understand that the MPG guage looks like a vacuum guage, but
it really is not or the needle would remain stationary as the vehicle rolled
to a stop. Since the needle moves, then the indication has to be a
measurement of fuel consumption vs. speed.

The temp guage is perhaps the most useful guage of the bunch. The condition
of the engine is a function of the heat of the engine.

As for the original question,
I can't tell you if what you saw is accurate or not. I see no reason for the
difference in guages of the 328 and 335, except that the 335 would need a
guage or two to tell one about the activity of the Twin Turbos.

On Jul 4, 8:48 am, "Jeff Strickland" > wrote:

> As for the original question,
> I can't tell you if what you saw is accurate or not. I see no reason for the
> difference in guages of the 328 and 335, except that the 335 would need a
> guage or two to tell one about the activity of the Twin Turbos.

Now you made me second guess myself. :-)

They have a picture of the 335i gauges he
http://tinyurl.com/34wc2l
And the 328i gauges are he
http://tinyurl.com/3dg6qa

I still wonder why they had to do that. There's got
to be a reason!

Anoop

On Jul 4, 7:55 am, "Jim" > wrote:

> As for the temperature gauge, it is also useless because all it really shows
> is that the engine is either cold or not.

I usually use the temperature gauge to tell me when I can start
shifting
at a higher RPM. I usually try to keep it below 4K until the engine
reaches its normal operating temperature.

Anoop

"anoop" > wrote in message
ups.com...
> On Jul 4, 8:48 am, "Jeff Strickland" > wrote:
>
>> As for the original question,
>> I can't tell you if what you saw is accurate or not. I see no reason for
>> the
>> difference in guages of the 328 and 335, except that the 335 would need a
>> guage or two to tell one about the activity of the Twin Turbos.
>
> Now you made me second guess myself. :-)
>
> They have a picture of the 335i gauges he
> http://tinyurl.com/34wc2l
> And the 328i gauges are he
> http://tinyurl.com/3dg6qa
>
> I still wonder why they had to do that. There's got
> to be a reason!


That's interesting, they took the fuel consumption gauge out of the 335 and
put a water temp gauge in its place. I can only guess that water temp is
more volatile in the twin turbo, so they want it to be more prominant.

In article > ,
Jim > wrote:
> Isn't the mpg gauges nothing more than an estimate based on engine
> vacuum?

If it were, it would read high at idle.

--
*Growing old is inevitable, growing up is optional

Dave Plowman London SW
To e-mail, change noise into sound.

Its not a water temp gauge but a oil temp gauge like the E92 coupé.
Oil temp is more important then a mpg gauge.
Who can buy a 335i, he is not interested in fuel consumption.


"Jeff Strickland" > schreef in bericht
news:sCWii.2997$Np2.2783@trnddc07...
>
> "anoop" > wrote in message
> ups.com...
> > On Jul 4, 8:48 am, "Jeff Strickland" > wrote:
> >
> >> As for the original question,
> >> I can't tell you if what you saw is accurate or not. I see no reason
for
> >> the
> >> difference in guages of the 328 and 335, except that the 335 would need
a
> >> guage or two to tell one about the activity of the Twin Turbos.
> >
> > Now you made me second guess myself. :-)
> >
> > They have a picture of the 335i gauges he
> > http://tinyurl.com/34wc2l
> > And the 328i gauges are he
> > http://tinyurl.com/3dg6qa
> >
> > I still wonder why they had to do that. There's got
> > to be a reason!
>
>
> That's interesting, they took the fuel consumption gauge out of the 335
and
> put a water temp gauge in its place. I can only guess that water temp is
> more volatile in the twin turbo, so they want it to be more prominant.
>
>
>
>
>

On Thu, 05 Jul 2007 09:00:28 +0100, "Dave Plowman (News)" >
wrote:

>In article > ,
> Jim > wrote:
>> Isn't the mpg gauges nothing more than an estimate based on engine
>> vacuum?
>
>If it were, it would read high at idle.

It is based on the amount of fuel being passed from the tank to the inj minus
the amount returned. However, the newer systems are based on the exhaust and
the time the injectors are open thus the inj time = fuel used (not burnt) /
vehicle speed or distance.

If you reset the computer average consumption at 60mph with the throttle closed
the reading will be about 90mpg but quickly drops to 60, 40, 35 etc as the
throttle (hence fuel injected) is opened/speed & distance.

So if you want to lie about MPG when selling reset the computer at 60 with the
throttle closed and stop when it reads 45mpg then show the intending buyer how
frugal you V12 monster really is - Look sir I get 38mpg out of this - give me
the money.....

Steve

> wrote
> So if you want to lie about MPG when selling reset the computer at 60
> with the
> throttle closed and stop when it reads 45mpg then show the intending
> buyer how
> frugal you V12 monster really is - Look sir I get 38mpg out of this -
> give me
> the money.....

As if someone buying a V12 was concerned about mpg in the first place...

Pete