What kind of FE instrumentation for Pre-OBD2 Diesel
 

Any suggestions on fuel economy gauge for my 1986 VW turbo diesel?

If you haven't noticed from my car choice; it has to be cheap.

I have thought about using a linear variable resistor and wiring it to an electric meter. Since the fuel is used directly by the position of the foot feed (and the rpm) I might have a relative way of improving my mileage.

What about some kind of crank trigger and magnetic pickup device to give you an "rpm" so to speak. It may not give a total and accurate RPM, but I would think it could be hooked to a gauge of some sort to give you feedback, even if the gauge says you are turning 8000 rpm at idle and 10,000 rpm at speed?

w terminal on your alternator gives a pulsed signal for RPM.

Boost guage.

EGT guage (peak EGT is best performance mixture) Lean (less throttle) of that gives better MPG.

sorry, i cannt help you, and i want to know th answer.

I am up against this problem as well. My truck has no instrumentation in line on the fuel. I'd need to have two flow devices, on for fuel in and one for return. It is cost prohibitive for me.

Yeah really not much to do unless we want to develop a fuel usage gauge where we could see GPH and then work backward to get MPG.

What I have done is to pull the start lever out. It seems to give better fuel mileage.

I am in the same boat on My 89/82 6.2 diesel, without GPH, no way to get instant FE.

I think something needs to exist for GPH.

vern if you are pulling the lever out for and it is making a mileage difference you may think about adjusting the injector timing.

my understanding of the VW injection system is that while pressure to the injector is over x value a spring allows the injector to open.

in the pump if a pressure measuring device "knew" when the injector was opening and closing by sensing the pressure in the line (vw uses a variable stroke injector pump) longer stroke means higher flow rate and longer duration with the injector open. that information could be fed to an MPguino.

What we would have then is frequency and duration which is handled well by MPGuino, unfortunately duration and volume of fuel is probably not linear, but that could likely be solved with software.

I just thought that diesel injestion timing may be "measured" by a microphone attached to the injector. Since it'a a fully mechanical unit it should be pretty easy with an oscilloscope to find the point and timing for actual injection. As I remember diesel (old type) injectors are set up for constant fuel pressure, so what's changing is time. If you could actually measure the time of injection you can actually find an amount of injected fuel. Combining that with some kind of vehicle speed sensor will give you a full MPG. I think it can be done pretty easily. I could try to do that but don't have access to any old diesel engine and what worst I don't have oscilloscope to find characteristic points of the measured sound.

Mechanical diesels normally use a lumosity probe adaptor that goes in a glow plug hole to detect combustion. The lumosity adaptors are typically used drive a standard gasoline timing light.
I have one and its so nice, not having to guess at your timing.

True, but you can check timing but not a fuel dose... I'm still thinking how to build a kind of OldDieselMPGduino :)

What FE instrument to use with old diesel
 

Hellow AndrzejM,

I have an old diesel myself and tried two ways to estimate fuel yield:

First way:

Compute real time speed (km/hour) and real time fuel consumption (liters/hour) and divide the first by the second, giving me km/l.

This way is noy easy, but is the best.

Getting real time speed: in my case this signal was already available, I just find the correct spot to get it. Check yr car´s manuals.

Computing fuel consumption:

I constructed an arduino device, and second, I installed two tiny electronic flow meters: one on the main fuel conduct (from feeding pump to injector pump) and the second in the fuel return pipe (from injector pump to tank).

Then I read both signals to Arduino and calculated the difference between them. That is the real time fuel consumption.

Of course, it is necessary to build a program to compute all variables and I found that signals are very unstable, so decided to compute a moving average value instead. Every 5 seconds I computed the fuel efficiency using these moving average values.

Second way (easier):

Using the same Arduino board, I constructed a math model (armonic curves) where fuel consumption was a function of only two variables: rpm and throttle position.

(Using this method, you don´t need the fuel meters, which are very difficult to obtain for the tiny fuel flow. Besides, a gentleman from Suiss gave them to me, but they stop working after some months. After that, they broke producing a fuel spill).

At a fixed throttle position, fuel injected by the injection pump depends only on rpm. It is a convex ascending curve, if you know what I mean. I found the curve for my injection pump (a Zexel rotative, probably the same you have) with a pump repare shop and made a family of almost parallel curves where each level represented a throttle position.

This method won´t give you absolute exactitude but will give you very good relative exactitude for comparison purposes. And the model can be adjusted to tank measures, making it very good for estimating real fuel yield of yr car.

If you need more information, please ask.

Best,

OldBeaver

Hi OldBeaver,

Thans for sharing. That's great idea but could you please share a bit more and let me know what type/model of flow meters you're using for your setup? I'm really interested in building such device on my own.

Best
Andrzej

Arduino based instrument for fuel flow measure
 

Andrzej,

As I told you, the flow meters didn´t last for long, as they where adapted from other use (they are not designed for fuel flow). I lost the contact with the source with my old hard disk, but if I found it, will send it to you.

There is another guy in this forum that made something similar. Look here:
http://ecomodder.com/forum/showthrea...pace-2115.html

May the Luck be with you !

OldBeaver

More on MPGuino for you
 

Look here:

MPGuino - EcoModder

OldBeaver

Old Beaver - I've build MPGuino on my own but for Previa which have gasoline engine. :)

Anyway I found interesting flow meters for diesel fuel, just take a look here:
Flow Meters

Thank you!
I sent them this email to see what I can find out.
It would be so slick to build an arduino based flow and totalizer that also took care of all my other needs.

I'm glad I could help. :)
And please keep me posted on the subject.

will do! I found this earlier, $705 for a somewhat crude analog display and totalizer for my truck.
Floscan Instrument Co. Inc.
I'm hoping for better from your link.

I'll keep my fingers crossed! :)

I started a convo with an engineer over there (Germany). We shall see.

That's great! I've found another source for flow meters in Poland. I'll contact them when I'll get back home. I'll keep you posted.

I got a quote as follows:
1) Art.-no.: 97478334, FCH-m-ALU- 2 x 1/8 IG", 0,05 - 8,0 l/min, 4 x Imp./U

Price: 136,50 Euro / pcs. (1- 9 pcs.)

that is about $179.50 US, per flow device. It puts out 3600 pulses per liter as far as I can tell. I am emailing for clarification on that.
We'd need to arduino a pulse counter and totalizer of our own with this option.

Thanks! I'll see what details and prices I'll get from that polish company. We'll be in touch.

Hi again!
I've found another vendor for flow meters and the good thing is that it has a branch office in the USA

Here's a datasheet of flow meter that should work for diesel in passenger car
DOM x0.5

The price is high, around 400 Euro but engineer that I've talked to told me that they can actually lend me a pair of those for testing. :D

400 per pair, or each? Looking at those, I'd want them downstream of a filter of some sort.
That means an accessory pump in my situation, I don't think I'd want to drag the fuel through a filter and a meter to get to my lift pump.

400 each - unfortunately :(

I'm also interested in using an Arduino for this purpose. I am thinking about using a MAF. Since it measures air flow and I know the air to fuel ratio I ought to be able to calclulate the fuel consumed. Any reason it wouldn't work?

Thing is, you don't know the air fuel ratio in a diesel. It can consume and pass through excess air quite readily. Watch your EGTs. When they are low, it is not just because power is low.

Well that's not fair! :D Seems I've got a lot to learn being my first diesel.

Lower cost sensors
 

I found 2 sensors that are lower in cost, one is from Futurelec
it's the FLOWFUEL30L0.
The other is from Bio-tech it's the Low flow flowmeter- FCH-m-POM-LC, Q= 0,015- 0,8 LPM
I'm a new member so can't post the links, and can't quote links from some one else's post as a quote grrrr
Bill

Let me help you with that:

FLOWFUEL30L0 - 2.0 to 30.0 L/min Diesel and Gasoline Flow Sensor

FCH-m-POM-LC -0,8 LPM 97478617 : B.I.O-TECH Flowmeter

Thanks Billy!
Don't let that link title fool you, it is 2.0 to 30 Liters per hour.
Liters per minute would be worthless, LOL.

Would having a an Air Fuel Ratio gauge help?

Not really, but I just have an idea to combine MAF and lambda sensor, If we would know the exact amount of the air entering the engine, and the amount of the oxygen in the exhaust, we could approximate the amount of fuel used.

What do you think of that?

It would take two of the $12.90 flow meters, one on the fuel in and one on the return, and a cheap microprocessor with an LCD display for my truck. I am very interested!

Yes, that will be the easiest and the most accurate thing to do.

I have a few other functions to automate, and no programming experience. am I screwed? :D

I can help you with that, when I'll find a while. Tell me what other things you want to automate.

How do you compare fuel usage to distance on a real time basis.