Trip Computers / Maxidot

[Timelord1.9Tdi]

Hi

A question for all to ponder here, regarding how computers are fed information to gauge how much fuel is used per gallon.

A Asumption of mine, as I am unertain, but I am guessing that there isa flow valve with a sensor, similar to that of a water meter, measuring how much fuel going through it and with the information supplied by other sources supplying Distance Travelled etc, then this calculates the average MPG and reports it to you in the obvious manner.

As I said, an assumption, would love to know though (Factually)

I also have a argument that the Brim to Brim method has flaws, for example as we already know all pumps vary when it comes to cut off points, then there is the point that who fills to the point the pump cuts out or do ppl squeeze more in !! Also different tempeture effects fuel as well therefore cut out point of the nozzel also do ppl do an exact calculation ???

With the concerns above which is really more acurate the Trip or the Brim 2 Brim method ???

So what is your thoughts on this I look forwards to hearing your oppinions

Timelord

[skodayouth]

Hi

A question for all to ponder here, regarding how computers are fed information to gauge how much fuel is used per gallon.

A Asumption of mine, as I am unertain, but I am guessing that there isa flow valve with a sensor, similar to that of a water meter, measuring how much fuel going through it and with the information supplied by other sources supplying Distance Travelled etc, then this calculates the average MPG and reports it to you in the obvious manner.

As I said, an assumption, would love to know though (Factually)

I also have a argument that the Brim to Brim method has flaws, for example as we already know all pumps vary when it comes to cut off points, then there is the point that who fills to the point the pump cuts out or do ppl squeeze more in !! Also different tempeture effects fuel as well therefore cut out point of the nozzel also do ppl do an exact calculation ???

With the concerns above which is really more acurate the Trip or the Brim 2 Brim method ???

So what is your thoughts on this I look forwards to hearing your oppinions

Timelord

I dont think it involves any extra hardware, i think it uses the existing fuel injection data such as m/g stroke of fuel, engine load and throttle position and fuel remaining

[giandougl]

Hello,

No doubt there is a sensor in some unit where fuel flows, measures resistance in its actual rate of flow. As flows ebbs or increases it's monitored and a electronic message is sent to another sensor which then sends it to a the visual meter that you see.

Like you haven't a clue how it's done and will be just a little wiser if I did really know and understand it's workings.

It's just something to fiddle with when bored on a mororway, or waiting for the missus nip into the shop with the engine still running. LOL

Good-luck with your quest. Ian. 01/05/2009

[Timelord1.9Tdi]

Hello,

No doubt there is a sensor in some unit where fuel flows, measures resistance in its actual rate of flow. As flows ebbs or increases it's monitored and a electronic message is sent to another sensor which then sends it to a the visual meter that you see.

Like you haven't a clue how it's done and will be just a little wiser if I did really know and understand it's workings.

It's just something to fiddle with when bored on a mororway, or waiting for the missus nip into the shop with the engine still running. LOL

Good-luck with your quest. Ian. 01/05/2009

Thats true, and lmao

[skodakid]

I dont think it involves any extra hardware, i think it uses the existing fuel injection data such as m/g stroke of fuel

That is exactly how its done along with speed/distance information.

Injectors, fuel pressure regulators are subject to manufacturing tolerances. More significantly errors in measuring speed/distance due to tyre rolling radius and tyre creep/slip (nb all tyres do this all the time it causes most of the error as it is a variable), hence the "inaccuracy" of this method - some trip computers can be pretty accurate, but a lot tend to be 5-10% optimistic.

Brim to brim calculations are frought with problems. As mentioned, temperature, cut off points, method used, car attitude are all variables. Will only be reasonably "accurate" when averaged over several tankfuls and using a meticulous methodology.

[Timelord1.9Tdi]

That is exactly how its done along with speed/distance information.

Injectors, fuel pressure regulators are subject to manufacturing tolerances. More significantly errors in measuring speed/distance due to tyre rolling radius and tyre creep/slip (nb all tyres do this all the time it causes most of the error as it is a variable), hence the "inaccuracy" of this method - some trip computers can be pretty accurate, but a lot tend to be 5-10% optimistic.

Brim to brim calculations are frought with problems. As mentioned, temperature, cut off points, method used, car attitude are all variables. Will only be reasonably "accurate" when averaged over several tankfuls and using a meticulous methodology.

Brlliant, that makes sense I am keeping record both on Spiritmonitor.de and on a excel document to keep track

Timelord