Fuel Gauge question

[njaremka]

ZiO: i meant all NEW cars, but no harm done.

Red Baron: BMW's have a milage gauge!

 

[Red Baron]

ZiO: i meant all NEW cars, but no harm done.

Red Baron: BMW's have a milage gauge!

Sorry to ask but what does a "mileage gauge" do?(silly)

 

[njaremka]

if you have ever driven a BMW, they have a gauge that shows your instintaneous fuel milage. all it really is, is a vacuum gauge that moves based on your throttle position. some aftermarket vacuum gauges have fuel economy markings on them, too.

 

[Red Baron]

if you have ever driven a BMW, they have a gauge that shows your instintaneous fuel milage. all it really is, is a vacuum gauge that moves based on your throttle position. some aftermarket vacuum gauges have fuel economy markings on them, too.

So it gives you the mpg thing, right? But not the actual quantity of fuel left in the tank, or does it also do that?

Yes I have driven a BMW, it was an M6 (beefed up M635CSi I believe), but it was so long ago (October 1988) I can't remember if it had a mileage gauge on it. But honestly, if you can afford a bimmer, do you care about the mpg's?

 

[njaremka]

if i could afford a 'bimmer' (the motor cycles are 'beemers') i know fuel economy would be last on my mind.

and i did a quick search, couldn't find any "M" cars with the fuel economy gauge, but i did find this on the bmwusa.com site:

the fuel economy gauge is below the tach. what i found in my search is that the "M" cars seem to have that spot taken with an oil pressure gauge.

 

[Red Baron]

if i could afford a 'bimmer' (the motor cycles are 'beemers') i know fuel economy would be last on my mind. (clip)

BMW's are real nice, it used to be a dream of mine to own an M3 or a 540. But, honestly, I prefer to pay the mortgage on the house and the P5 is the best car I've owned. Why would I search elsewhere? With age, you tend to appreciate what you have (it fills the garage anyway). I now go by this say : "If you have to ask the price, you simply can't afford it".

Thanks for the photo of the BMW's dashboard, the P5's looks just as nice for me (sure would love an oil pressure or temp gauge though).

 

[Don]

I also noticed that in my last 2 cars (both Civics). Why the hell can't they use some kind of sensor in the fuel line that measures the amout of gasoline that goes by? Another sensor could be used to tell initial quantity at fill-up (say, when you press the Trip button, it takes a reading). A simple computer could do the math...

In the old days, this was a pretty simple computation - They actually had "trip computers" in some old cars, and you could buy aftermarket ones and add them to your car pretty cheaply.

On a carburetted car, ALL the fuel that went forward in the fuel line was actually consumed by the engine, so the math was pretty simple.

Fuel injected cars only burn a portion of what the pump sends to the engine, and the rest is returned to the tank by a separate line, so "measuring what goes by" doesn't do you too much good, unless you also carefully measure what comes back.

You can easily calibrate a fuel flow sensor by letting it pump a bunch of gas, and then "telling it" that the amount that flowed by was exactly so many liters/gallons. Harder to do when you have two sensors to deal with, and you have no idea just how much fuel is coming back on the other line.

I'm sure it can be/is being done, but doubt that accurate technology is cheap, so we probably won't see it on Hondas/Mazdas for a while.

Don

 

[njaremka]

In the old days, this was a pretty simple computation - They actually had "trip computers" in some old cars, and you could buy aftermarket ones and add them to your car pretty cheaply.

On a carburetted car, ALL the fuel that went forward in the fuel line was actually consumed by the engine, so the math was pretty simple.

Fuel injected cars only burn a portion of what the pump sends to the engine, and the rest is returned to the tank by a separate line, so "measuring what goes by" doesn't do you too much good, unless you also carefully measure what comes back.

You can easily calibrate a fuel flow sensor by letting it pump a bunch of gas, and then "telling it" that the amount that flowed by was exactly so many liters/gallons. Harder to do when you have two sensors to deal with, and you have no idea just how much fuel is coming back on the other line.

I'm sure it can be/is being done, but doubt that accurate technology is cheap, so we probably won't see it on Hondas/Mazdas for a while.

Don

not all new fuel injected cars come with a fuel return line. the 99+ (or 2001+) miata do not have a fuel return line. and as such, they cannot accept an AFPR.