BMW 3 95myr M3 fuel level and coolant temp inputs to Dash2

[osborni]

The RPM is 3 pulses per rev if you are picking it up from the stock dash harness. The RPM display will be ,0,0,1,2,3,4,5,6,7 with the shift lights set to your preference. I have them with a 6,000 rpm flash and they start coming on at ~4,000 RPM - which lets me know that I'm on cam.

You will need to google the gearbox ratios and your rear diff ratio for the gear information. The 5th gear is 1:1 on my car (IIRC, the same on yours). When I set it up years ago, I had to put in 1.00001 as a ratio to make it work... Didn't like 1 for some reason. Works fine with 1.00001 but I don't know if that bug has been fixed.

[zola1]

Thanks Osborni , Good solid advice will pull my finger out and get on it ...on the rpm i noticed the rpm was reading high on the initial start up . i will try the change in pulse to revolution .. , i 'll be in touch once i've got some knowledge of the config.

cheers for the advice spot on

[zola1]

Getting along with the config but have a question, fitting an oil pressure sensor with the following spec.

3 Wire sensor -0v, +12v input and +V Output range is :-

0 Bar = .5 volt

7.5Bar = 2.5 volt

15 Bar = 4.5 volt

Now i can enter those three values in the "Generate by table, by the X Y excel table entry method" but how do i get the accuracy up to say 108 psi (7.5Bar), do assume the sensor is linear and do the maths and find say 20 figures and input them ....i removed a 0-80psi OEM oil press Gauge so this looks like the range i need say 0-7.5 bar .

Any thoughts

cheers

[Support]

Zola1,

To improve the accuracy you would need to use a sensors that outputs a bigger change in voltage between 0-7.5 bar.

The current sensor is outputting 2v for the range you are using 0-7.5, which is OK, it will be accurate to around 0.03 bar using the DASH2 inputs.

Kind regards,
K

[zola1]

Hi,

Thanks for info, the sensor is ratio metric and needs exactly +12v supply (not the potential 13. 6 -14.4v from the car supply !!)...is there a +12v reference output i can use from the DL1 or Dash 2 pins ?

I have looked at the pinout and there are some unspecified pins, Do you know their functionality ? :-

Dash 2 Conn 2 Pin 7 (M) Listed as No Connection ?


Dash 2 Conn 2 Pin 12 (S) Listed as No Connection ?

Bit of a long shot, is there a function in the software to overcome the offset created by the variable supply ?

thanks

Derrick

[osborni]

Ratiometric at 12 VDC is going to be a problem. Car voltage will fluctuate quite a bit and the DL1/Dash2 only has a modest 5VDC supply. Low drop-out linear power supplies are flaky as well. Your best bet is a power supply from a "car-computer" so you can get a reliable 12VDC or just buy a new pressure sender that runs off 5VDC.

The best I could do was a 10VDC linear power supply and have it be stable over the range of expected car voltage.

[zola1]

I 've tested the sensor on a calibrated bench power supply and it gives a steady 0.5v in "free air"... regardless of the input voltage between +10v -+15v. I will fit it and see what kind of results i get .. (i'm not sure if it only goes ratio metric when pressure is applied to the sensor) i can get hold of a 5v one just not at the moment i will go ahead and fit it (same size thread on sensor and pinout ) so it won't be much rewrk to change later.

i'll et you know how it goes.....

btw the Dash software doesn't seem to like Vista OS what OS are you using ?

cheers

[zola1]

Hi,

I got the voltage to litres added figure from a dry fuel tank to full.. for the fuel level.

A total of 25 lines of X (volt change) & (y) Litres.

result =

formula above graph = +44.26 -6.39 std dev =0

Load config and view dash

[b]Dash displays a minus number -4.699[/b] tank is full and Dash should read 60 Litres !!!

Entered in the excel sheet, pressed ok , then saved config, went to view the saved confi by importing that config ..But graph had disappeared !!!!to be replace by 3 random plots .. I tried with just two lines still the same problem.

Found this in knowledge base

The box is divided into 3 areas:

The table to the right of the box is where the table for the calibration data is entered. The input data is entered into the left hand column and the output is entered into the right hand column. The information must be entered in pairs and there must be between 1 and 25 unique points entered for the program to calculate an equation. As you enter or edit each point you will see that the graph and the equation update.
The graph to the left of the box displays both the data points that have been entered (they are shown as the + marks) and the equation that has been fitted to the data (the equation is shown as the curve). The graph is scaled according to the input/output data points that are entered into the table. You can edit the points on the graph (which also updates the table). To do this select the point on graph by click on it and then move it using by holding down ctrl and using the cursor keys.
Finally at the top of the box the equation is displayed, as well as the standard deviation of the fit. The standard deviation indicated how well the data fits the points, a standard deviation of 0 is a perfect fit, the higher the number, the worse the fit.

There are a couple of things to note:

The equation that is fitted to the data is the best fit by minimising the square of the error between the data points and the curve - however it's not always possible to force the equation though all the points, it simply does the best that can be done.
Equations are very useful for interpolation, but useless at extrapolation! For example if you calibrate an air temperature sensor from 10 degrees to 80 degrees, then the sensor should only be used over this range - the calibration would not be valid at 100 degrees for example.
You can cut and paste the information from the table into and out of excel by highlighting the data and right clicking, then selecting the required option.
If you click OK, the the equation is applied to that channel, if you click cancel all the changes are discarded. In all cases once you close the dialog box there is no way to recall the data points that you entered. If you think you might want to go back to the original data at some point, then the user is advised to cut and paste the data to an external source. ...Does this mean you have to keep re-entering excel data and fudge the graph to get it to....?


Am i not doing some basic function, very frustrating .

Would it better in the enter an equation manually tab please can you advise what data goes in the 4 fields ? there is no mention of the y axis ?/

Output = (what data goes in here ?) x Input 3 +

(what data goes in here ?) x Input 2 +

(what data goes in here ?) x Input +

then final box here ?

any thoughts

cheers

[zola1]

osborni,

I cannot work out how to input the data to cal to the TPS input i have put into Analogue 1 on the DL1-3 Logger !! ...

Done this :-

You wired in the TPS - the sensor is already there (on top of the throttle body) and basically free. If I remember, it's the #2 wire (middle wire) that is the signal. Just tap into it and you have a great set of data on how good you are with throttle application and will know when you are at WOT.

Measured the Voltage on the wire i ran to the DL1 = .5volt closed throttle- 4.1v WOT. inserted into A1 of DL1.

Opened DL1 mK3 config software :-

I then entered the two figures in a plot on the "Set conversion for throttle angle" - Generated a equation for a table. got Y=(12.5v )-6.25.....does this seem correct ?

1).How does this show on the Dash 2 ?

I not sure if this is the right set up how did you get the correct display on the dash?
any advice would be much appreciated

cheers



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[osborni]

As a general rule I don't put conversions into Analysis or the Dash2 until I've confirmed that the raw voltage is what it is supposed to be. i.e., recorded some trial data and looked at the screen with everything up and running. THEN I put in conversions.

The table should be:
Input X Output Y
0.5 0
4.1 100

assuming you want to use 0% to 100% throttle.

(don't forget to mechanically check that the throttle body is at WOT when the pedal is bottomed out - I find that mine needs to be tweaked once a year or so. Throttle cable stretches apparently)

A1 of the DL1 is fine. You need to ensure that the DL1 is sending that data via the serial bus in the DL1 config tool. The column "serial data" should have a 10 or a 25 hz value.

THEN you need to ensure that the Dash2 reads the data as well in the Dash2 config tool. You need to put it onto one of the "setup screens". Apply averaging and rates of change here and change the name to something logical like TPS. Drop the decimal places since 0.1% of a 100% throttle is useless.

When on track, this is a 2nd tier bit of data. I only use it for post session analysis so I know when and how I use the throttle. So it's on Display #3 - which I only use to ensure I'm actually recording data in the pits. Along with other stuff like steering turns and water pressure.

[osborni]

Would it better in the enter an equation manually tab please can you advise what data goes in the 4 fields ? there is no mention of the y axis ?/

Output = (what data goes in here ?) x Input 3 +

(what data goes in here ?) x Input 2 +

(what data goes in here ?) x Input +

then final box here ?

any thoughts

cheers

Use the table, it auto-generates the equation for you. Voltages go in the Y column and what you want out goes in the X column.

If you post the raw data, I might help.....

[zola1]

Would it better in the enter an equation manually tab please can you advise what data goes in the 4 fields ? there is no mention of the y axis ?/

Output = (what data goes in here ?) x Input 3 +

(what data goes in here ?) x Input 2 +

(what data goes in here ?) x Input +

then final box here ?

any thoughts

cheers

Use the table, it auto-generates the equation for you. Voltages go in the Y column and what you want out goes in the X column.

If you post the raw data, I might help.....

Is it that i am enter the data in reverse ! ? as you mention above ..i have highlighted in BOLD ..or is that a typo ?

Anyway :-

Here is the raw data..i am only really after accuracy below 30L (half tank)..full tank figure is also required. X=Volts input Y = Fuel Level.

1.55 60
1.51 58
1.47 56
1.45 54
1.43 52
1.41 50
1.38 48
1.23 46
0.983 36
0.882 30
0.805 28
0.803 26
0.768 24
0.707 22
0.671 20
0.607 18
0.561 16
0.502 14
0.444 12
0.389 10
0.337 8
0.272 6
0.208 4
0.148 2
0.116 1

does anything look strange and if yes would it cause the minus figure on a full tank ?

cheers

[osborni]

Dude, I'm gonna start charging consulting fees... (frankly, all of this stuff is in the manual or the knowledge base...)

Data in the table (input and output....):


The equation that generates:


And how to put it into the "enter manually" fields (see the connection? It's a polynomial short hand....):


I also put in some basic settings for the dash display.

Name = Fuel

Decimal places = zero

Samples to average = 100 (takes care of tank slosh)

Max rate of change = 1 (probably can be lower as fuel doesn't go down that fast... like 0.1... need to make a decision here. lower number means you won't get spikes, but then you might miss if you have a fuel leak... I'd set it at slightly higher than the max expected fuel consumption. I get ~8mpg on track which translate to ~3.5 KM per liter) I'd probably just leave it blank and play with it later if I needed too.

A low alarm of 5 liters.... need to decide here too. I'd give you a few liters before you get mid turn fuel starvation... (sorry, made a mistake in the picture - needs to be in the low field, not the high field - but I'm not going to re-do the screen shot )

You also need to set up the DL1 to send the analog channel over the serial bus....

I'd go into how to pick the right frequency of data to collect and to put on the bus, but we'll leave aliasing alone for now....

[zola1]

Hey,

thanks you are a star ....i will follow your instructions and let you know how it goes .

cheers for all your efforts it is much appreciated .

[zola1]

Osbourni,

A question on the OEM BMW 3 Series Bosch Water and Oil Temp sensors 2 wire NTC type.

Like i did with the fuel sender :-

Is it a case of generating a table of 25 i/o's for the x y figures from a Cold Engine all the way up Maximum Coolant/Oil Temps using an accurate method of establishing the temps ( thermocouple or thermometer )....then measuring the volts input to the Analogue channel .to then input this into the config, to get the most accurate Dash read out ?

Is there other no way of getting the cal from any other source.
How did you manage to get accurate readings on your car .?

Just as a trial I did try using the Select a sensor from the drop down list but the Bosch pt no's do not match the sensors i have in the oil and coolant , so they are 20 deg C out e.g they start from a cold engine in minus reading and then when the rad cooling fan kicks in at 91 deg C the dash read 70 deg C.