Flow sensor integration with the Car electronics system

Thread Starter

boodlefin

Joined Mar 23, 2023
5
I need to integrate a Fuel flow sensor mentioned here to the car dashboard system, so as to display the flow readings on the dashboard screen and/or to a seperate display screen when fuel passes through the sensor .
I'm specifically using this device which has a Working Voltage: DC 5V~18V.

Please suggest to explain what options are available & how this can be done electronically with the different car systems models?
 

Irving

Joined Jan 30, 2016
4,047
Welcome to AAC.

That flow-meter is for water, are you sure it is fuel-safe? Flow-sensors for petrol etc. have to be certified against leaks. Additionally how are you going to connect a 6 - 10mm dia fuel pipe to a 1"(25mm) dia flow-meter?

That said, connecting to most car electronics is a non-starter, as they are highly integrated using a CANBus network in all modern vehicles for at least the last 20+years. It would have to be a seperate display, but what value is it to the driver?

This sounds like a school project.
 

Mullins

Joined Dec 31, 2021
179
You will not have any reading. Especially if your fuel line is returnles. This because the fuel flow will be under the minimum of the reading of this instrument. Instead you can do a different and better job. Since the pressure remain constant on the fuel line you can check the injection time to know how much fuel is going on the car.
P.s maybe some one will tell you that the pressure change in some car by the small pipe between the fuel pressure regulator and intake manifold But it's happening for small time when you push quick acceleration pedal.
 

Reloadron

Joined Jan 15, 2015
7,579
When choosing a flow sensor choose the sensor based on the medium you plan to measure. I would not use a plastic housing designed for water. Not just because it may leak but because fuels like gasoline or diesel fuel may just eat right through a plastic housing not rated for fuel. Years ago my quick fix fuel line repair involved using a piece of windshield washer hose. I only planned it temporary. The very next day the fire was fast and sudden. Gasoline ate right through my temporary fix. Buy a flow sensor designed for fuel and one designed for the fuel line pressure.

How you interface it is going to depend on the sensor output. Most just deliver pulses. They will have an average mean K factor which is pulses per unit of measure. With that known it's a matter of doing the math on your receiving end.

Ron
 

LowQCab

Joined Nov 6, 2012
4,290
It's much easier to design a Circuit to tap into the MAF-Sensor-Output,
( Mass Air-Flow-Sensor ),
all modern Cars have one, even some Diesels are now using them.
It will very accurately indicate how much Fuel is being consumed.

The only condition where there may be some small discrepancy is
during WOT ( Wide-Open-Throttle ) operation,
where the Fuel-Mixture will change from an exact 14.7 : 1, ( ratio by weight ),
to somewhere around ~12.5 : 1, for a few seconds.

Some Cars have a simple 0 to 5-Volts DC Signal for the MAF-Output,
others use a Variable-Frequency-Output, ( General-Motors and a few others ),
which may complicate things somewhat.
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Thread Starter

boodlefin

Joined Mar 23, 2023
5
Welcome to AAC.

That flow-meter is for water, are you sure it is fuel-safe? Flow-sensors for petrol etc. have to be certified against leaks. Additionally how are you going to connect a 6 - 10mm dia fuel pipe to a 1"(25mm) dia flow-meter?

That said, connecting to most car electronics is a non-starter, as they are highly integrated using a CANBus network in all modern vehicles for at least the last 20+years. It would have to be a seperate display, but what value is it to the driver?

This sounds like a school project.
@Irving - 1) This is not the best product but to start with, can be used with fuels. e.g. similar plastic sensors for diesel. https://www.amazon.in/Turbine-digital-turbine-counter-measure/dp/B093ZNNY84 . Planning to move to other sensors as we progress. If you know any better compact, cost efective,accurate sensors that can do the job, please do share.

2) Not connecting with fuel pipe but fit around the tank's fuel cap so that when the vehicle is refueled, it notifies the actual volume amount going in the vehicle. (Yes, short-fuelling is a problem in many countries)

3) Which is the simple, Compact, cost effecient way to get refueling volume displayed to the users? On a seperate device or on a app or send a notification on SMS/Whatsapp? Please help share more in detail on devices available for each option & how it can be achieved?
 

Thread Starter

boodlefin

Joined Mar 23, 2023
5
You will not have any reading. Especially if your fuel line is returnles. This because the fuel flow will be under the minimum of the reading of this instrument. Instead you can do a different and better job. Since the pressure remain constant on the fuel line you can check the injection time to know how much fuel is going on the car.
P.s maybe some one will tell you that the pressure change in some car by the small pipe between the fuel pressure regulator and intake manifold But it's happening for small time when you push quick acceleration pedal.
- @Reloadron @LowQCab Thanks for inputs.
This device is to address short-fueling.
1) This is not the best product but to start with but can be used with fuels. e.g. similar plastic sensors for diesel. https://www.amazon.in/Turbine-digital-turbine-counter-measure/dp/B093ZNNY84 . Planning to move to other sensors as we progress. If you know any better compact, cost efective,accurate sensors that can do the job, please do share.

@Mullins
2) Not connecting with fuel pipe but fit around the tank's fuel cap so that when the vehicle is refueled, it notifies the actual volume amount going in the vehicle. (Yes, short-fuelling is a problem in many countries)

3) Which is the simple, compact, cost effecient way to get refueling volume displayed to the users? On a seperate device or on a app or send a notification on SMS/Whatsapp? Please help share more in detail on devices available for each option & how it can be achieved?
 

LowQCab

Joined Nov 6, 2012
4,290
What is "Short-Fueling" ???
Are You talking about an Engine running with a "Lean" Fuel-Mixture ?

The Engine Computer knows exactly what it's doing,
provided that all of the Sensors are working properly,
and if they're not working properly,
9 times out of 10 the Computer will self-diagnose the problem
and will "Throw-a-Code", ( store a Fault-Code in it's Memory ),
and turn on the "Check-Engine-Light".

What problem are You trying to solve ?
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Thread Starter

boodlefin

Joined Mar 23, 2023
5
What is "Short-Fueling" ???
Are You talking about an Engine running with a "Lean" Fuel-Mixture ?

The Engine Computer knows exactly what it's doing,
provided that all of the Sensors are working properly,
and if they're not working properly,
9 times out of 10 the Computer will self-diagnose the problem
and will "Throw-a-Code", ( store a Fault-Code in it's Memory ),
and turn on the "Check-Engine-Light".

What problem are You trying to solve ?
.
.
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Did you get a chance to google 'Short-fuelling'? A type of fraud!
 
Since the pressure remain constant on the fuel line you can check the injection time to know how much fuel is going on the car.
If you can sniff the "on time" for (at least) one of the injectors you have enough information to calculate actual fuel flow. Older vehicles have a regulator on the fuel rail to maintain constant rail pressure relative to manifold pressure mechanically whilst newer vehicles with a returnless fuel system have a manifold pressure sensor and control the pressure by PWM to the fuel pump. The end effect is the same, with fuel flow determined by injector on time regardless of manifold pressure. The on time typically varies from around 2.5ms to 18ms from idle to full throttle. The time lost to turn the injector on is about 1.0ms after which the flow rate is very close to constant, so subtract 1ms from the on time.

So sniffing the voltage of the injector transistor driver and counting the pulses (i.e. RPM) would give enough information to get an accurate repeatable flow rate. Calibration could be approximate to get started if the total fuel consumed is set to zero when the tank is filled and this total is compared to the amount of fuel added at the next re-fill to get a ratio for better calibration.

All the usual caveats about messing with EFI apply!
 

LowQCab

Joined Nov 6, 2012
4,290
Don't trust your State-Government certification Offices ?
Then move to another State.

There's an extremely small adjustment range for the output of a Gasoline dispensing Pump.
They are "Positive-Displacement" Pumps,
designed from the ground-up to have bullet-proof reliability and accuracy.
They are tagged and sealed after inspection.
Any discrepancy is going to be minuscule.

How much Fuel evaporates out of your Fuel-Tank ?

Do You know how much Water is in the Gasoline that You are buying ?

Do You drive around for a half an hour to find a Gas-Station that is 2-cents cheaper ?

Do You know what "Top-Tier" Gasoline certification is ?,
and how much repairs are going to cost You if You don't use it ?
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Last edited:

Alec_t

Joined Sep 17, 2013
14,405
Not connecting with fuel pipe but fit around the tank's fuel cap so that when the vehicle is refueled, it notifies the actual volume amount going in the vehicle.
The type of flow-meter shown in the link has to be fitted to the fuel inlet pipe so that fuel flows through it. That would likely be illegal in many jurisdictions and could invalidate vehicle insurance policies.
 

Irving

Joined Jan 30, 2016
4,047
The TS is in India. Western concepts of accuracy and regulation, outside major cities may not apply (or even in them, based on my limited experience of working there in New Delhi and Bangalore in the late 1990s).

So what the TS wants, and should have explained at the start, is to measure, more accurately than the fuel gauge (which on most cars is fairly inaccurate anyway) how much fuel has been deposited in the tank by measuring the flow rate over time in the filler pipe.


A suitable fuel-rated sensor of the type suggested, measuring flow over a time-period triggered by a non-zero flow rate should be good enough, say within a few % points, to determine whether short-fuelling has occurred.

A simple single board computer, eg ESP32 or similar and an app on the phone, communicating via Bluetooth is easy to implement (i did something not dissimilar for a tachometer a year or so ago) and works well in an automotive environment subject to good supply rail regulation and decoupling (i recommend an isolated dc-dc converter, it just makes its so much easier to get a clean supply).
 

Irving

Joined Jan 30, 2016
4,047
A load cell on a mount point for the fuel tank might be a better, if harder to install, option.
Interesting idea, but environmentally a mount-point could be tricky and its likely to be non-linear. Also its a relative rather than absolute measure.
 

Mullins

Joined Dec 31, 2021
179
as a mechanic I can say load cell is not a good idea because the tank is shaking on the road and if you use a strong load cell you will lost the accuracy. Second in the tank bolt the forces are in different directions, load cell need forces only in one direction.
This morning I lost a lot of time in hospital and I was thinking about an ultrasonic sensor to calculate the volume of the tank excluding the part of the fuel. But I didn't find anything like that. There are some ultrasonic sensor to calculate the distance from sensor to the liquid level but it will not work well when the car is not in perfect horizontal position.
 

Reloadron

Joined Jan 15, 2015
7,579
OK so this comes out to be checking for "short fueling". This is where I place my trust in my county department of weights and measures. They periodically show up and check not only gas stations but scales for example used to weigh goods being marketed. If measuring dispensed fuel you would use a totalizer function and not a rate function. While I am worried about being shorted on fuel should I also be concerned with my residential water meter? Natural gas meter? How about my electric meter? I have watched the county department of weights and measures show up unannounced and check the pumps at gas stations. They also analyze octane ratings to make sure you are getting what you pay for.

As to getting a totalizer measuring system for when I gas up our vehicles? I'll pass. Then too, one county administrator along with a county commissioner went to jail for corruption. :)

Ron
 

Irving

Joined Jan 30, 2016
4,047
OK so this comes out to be checking for "short fueling". This is where I place my trust in my county department of weights and measures. They periodically show up and check not only gas stations but scales for example used to weigh goods being marketed.
As i said in post #15

"The TS is in India. Western concepts of accuracy and regulation, outside major cities, may not apply (or even in them, based on my limited experience of working there in New Delhi and Bangalore in the late 1990s)."
 
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