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

zola1
Posts: 18
Joined: Sat Nov 19, 2011 4:47 pm

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

Postby zola1 » Mon Nov 21, 2011 8:41 pm

Hi all,

Can anyone help:-

1). As the OEM sensors for fuel level and water temp are variable resistors do i need to alter the signals to a voltage for the Analogue channel inputs ?

2) If yes, would you recommend using the +5v from Dash2 ...what pull up resistor value is best ? Please advise on the calibration for both sensor inputs ?

3) Is there any preset values in the software that are available for the BMW sensor ranges in Oil Temp .

Got a few more q's but i keep this first post short. thanks.

Any help would be much appreciated.

Support

Postby Support » Mon Nov 21, 2011 11:42 pm

Typically water temp sensors are 2 wire resistance sensors and this will need a pull up. Assuming it's a "normal" NTC type, then a 1k upto the 5v reference is fine.

Fuel level is different... they are more typically very low resistance and often 3 wire sensors. So in this case it might be best to leave it connected to the 12v battery supply and just take the signal to the DASH2.

Unfortunately we've got no information on these particular sensors and you will need to calibrate them yourself.

There is information of interest on the wiki:

http://www.race-technology.com/wiki/ind ... yOwnSensor
http://www.race-technology.com/wiki/ind ... FuelSender
http://www.race-technology.com/wiki/ind ... WireSensor

Kind regards,

Support

zola1
Posts: 18
Joined: Sat Nov 19, 2011 4:47 pm

Postby zola1 » Tue Nov 22, 2011 7:17 am

Hi,

Thanks for the info :-

Do you mean you this circuit ?


http://www.race-technology.com/forum/vi ... php?t=1822

Support

Postby Support » Tue Nov 22, 2011 10:02 am

yup!

osborni
Posts: 497
Joined: Fri Dec 07, 2007 9:08 pm
Location: USA, Michigan

Postby osborni » Tue Nov 22, 2011 3:25 pm

I don't remember if the '95 has one or two senders..... (I have an M Coupe)

BMW fuel level sender data from another forum:

http://forums.bimmerforums.com/forum/sh ... resistance

The two fuel level senders are in series, meaning you must add together the resistance of each side.

The resistance range for each fuel level sender is:
Empty: 10 Ω Â±2
Full: 250 Ω Â±5

So a full tank should give a combined nominal value of 500 Ω, empty 20 Ω.
BMW 2000 M Coupe

Chris Wilson
Posts: 4
Joined: Sun Dec 14, 2008 8:34 pm

Postby Chris Wilson » Tue Nov 22, 2011 5:19 pm

I assume these things do not give a linear output, due to the none regular shape of the tank. Have people managed to get an accurate fuel volume readout from such set ups, generally speaking?

Rob Stevens
Posts: 36
Joined: Sun Oct 31, 2010 9:36 am

Postby Rob Stevens » Tue Nov 22, 2011 6:09 pm

I see no reason why you can't just fill it up 1 litre at a time whilst the car is flat and convert the result into whatever you want, I don't the have a dash but a DL1 and I can do this as a custom formula, there is even a graph help to do this.

zola1
Posts: 18
Joined: Sat Nov 19, 2011 4:47 pm

Postby zola1 » Wed Nov 23, 2011 8:36 pm

thank for all for some great tech advice i will concentrate on the fuel level sensor issue first (need to confirm if it has two sender units ).

osborni many thanks for your heads up and link very good of you i will come back with some more info.

zola1
Posts: 18
Joined: Sat Nov 19, 2011 4:47 pm

config q's on Dash 2

Postby zola1 » Sun Dec 18, 2011 7:07 pm

Hi,

I have made up the potential dividers and fitted them, (thanks for the heads up) for the 3 analogue channels, i have wired at present.

Got the following voltages to enter in the calibration. Just getting into the set up phase !

1)Fuel Level. 260ohms (approx half a tank ) from the level in the tank, measurement= .967 volts at the input to the Dash 2 channel. looked at the trying to enter the value in the config, now correct me if i'm a mile of but is it best to do it by entering in the data via the "Generate an equation from the table below" tab.... see the excel info below ?

0 0.25
1 0.35
2 0.45
3 0.55
4 0.65
5 0.75
6 0.85
7 0.95
8 1.05
9 1.15
10 1.25
11 1.35
12 1.45
13 1.52

or as Rob suggested I see no reason why you can't just fill it up 1 litre at a time whilst the car is flat and convert the result into whatever you want, I don't the have a dash but a DL1 and I can do this as a custom formula, there is even a graph help to do this..........

How do you set it up to view the graph as you fill up ?...sorry for the basic q's but i'm new to this Dash2 software...is it in Lite Monitor ? If yes is it a process of :-

1).Plug in laptop USB lead to front port DL1 USB ... (i do not have a serial port on my laptop, so can only comms with USB) will the DL1 pass through the data to the dash via the RS232 LEAD i have run up to the DASH 2 ?

2) Open up Lite monitor on laptop ....then where do you go to monitor the Analogue Channel 1 input that will give me the fuel level voltage input ?

3) How do you view the graph data real time ....

4).How do you then transfer it to the config

Beginning to ramble a bit now....so will stop

Any help would be much appreciated

regards

osborni
Posts: 497
Joined: Fri Dec 07, 2007 9:08 pm
Location: USA, Michigan

Postby osborni » Mon Dec 19, 2011 1:33 pm

To be clear, you have a Dash2 as a stand alone? No DL1?

1) - Yes - Generate by table.

It would depend on how you want to think about your fuel level.

Typically either:

a) 0, 1/4, 2/4, 3/4, 4/4 full (well in this case it would be 0, 0.25, 0.5, 0.75, 1)

or
b) 0, 1L, 2L..... 60L (IIRC it's a ~60L tank)

Personally, if I had a race car with a fuel cell, I'd do liters to empty to make it easier to monitor approximate fuel consumption on the track. It would also make it simpler for post session analysis to monitor engine health. The math for liters per KM is simpler. (but you don't have a DL1?). The tanks on BMWs (as for most cars) are not linear. i.e., when the OE stock gauge says 1/4 full, it's really about 1/6 full, but 3/4 full is really 7/8 full or so.

X = input variable - i.e., voltage
Y = output variable - i.e., how you want to think about the volume of fuel in the tank. (I'd recommend Liters)

2) From the Dash2 ... (not quite sure as I've only used the lite monitor from a DL1 - but likely either analog 1-4 or analog 17-20 - the later is what the DL1 uses for Dash2 analog channels) - but then I might be thinking about your setup wrong.

3) Never bothered with that in real time. Don't even think you can do that with the lite monitor, just the full monitor program. What I would do is get everything powered up with an empty tank, then add 1 liter (or 5) at a time and record the voltages until the tank is full. paper and pen work just fine. Then put the values in per Q #1.

4) With a Dash2 as a stand alone, you need to connect it to your computer with a serial cable per the instructions. The same as when you flash new firmware in, but with the config tool.

Don't forget to save the config to your computer for editing later. I put a date stamp on them so I can keep track of revisions. ( "Dash (year month day) rX.dat" )
BMW 2000 M Coupe

zola1
Posts: 18
Joined: Sat Nov 19, 2011 4:47 pm

Postby zola1 » Wed Dec 21, 2011 8:40 pm

Hi,

No I have Dash2 & logger DL1

Ref this ..2) From the Dash2 ... (not quite sure as I've only used the lite monitor from a DL1 - but likely either analog 1-4 or analog 17-20 - the later is what the DL1 uses for Dash2 analog channels) - but then I might be thinking about your setup wrong.

1). As i have DL1 Logger and have hardwired the analogue
channels to the Dash2 ( please note : -i only have two wires to logger +12v and Gnd and and RS232 cable connected to Dash2). Does the dash just display the input voltage of the fuel level and the DL1 the "logs" the values over the data stream via RS232 ?

Can you confirm all is good with my existing circuitry ?.i hope i don't have to run the hardwiring down to the analogue inputs 17-20 on the DL1 logger !!

I now understand the cal for the fuel level ...Generate by table, by the X Y excel table entry method, a q's on this Y = output variable - i.e., how you want to think about the volume of fuel in the tank. (I'd recommend Liters............how is this displayed on the Dash2 ? eg.is this the actual display 20Litres Fuel Remaining or ?

thanks for the info :)

osborni
Posts: 497
Joined: Fri Dec 07, 2007 9:08 pm
Location: USA, Michigan

Postby osborni » Thu Dec 22, 2011 2:31 pm

Ah - DL1+Dash2 - more clear now.

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.

The 4 analog channels on the Dash2 show up as Analog 17-20 on the DL1 - if you are using them. (but I don't know what they will show up as on the Monitor - need to try it and see)

If you wire the sensors directly into the DL1, then they will show up as 1-8 just like you would expect.

1) Yes, DL1 logs the data as a serial stream from the Dash2. Make sure you have the "decode serial data" option checked in the DL1 config.

If you have both, then there is no reason not to wire the sensors into the DL1. You have more flexibility with sample rates and you don't have to worry about data corruption.

I would recommend that you have a separate power switch for the Dash2 from the DL1. The firmware is MUCH better than ~5 years ago, but once every 10 sessions or so, the Dash will flake out and I need to cycle the power to get it to re-boot. I'm 95% sure it's a corruption of serial data that does it. Also why I'd recommend that you use the DL1 as the primary input for sensors. Make sure you turn off the channels that you don't use to minimize the volume of serial data going back and forth. There is a caveat below...

I have the same setup as you, but I do run some sensors to the Dash, but only do so because my car is still street legal. The sensors that I run to the Dash are also lower sample rates. Temps and pressures. The DL1 is capable of higher sample rates for driver input sensors (brake pressure, throttle, steering, manifold pressure, etc.) I do not turn the DL1 on for street driving, so need the Dash2 to be independent and still have critical engine parameters.

My sensor map:

Dash2
1 - oil P
2 - oil T
3 - water T
4 - free (likely put in fuel level at some point....)

DL1
1 - volts
2 - water P
3 - free
4 - TPS
5 - Front Brake P
6 - Steering angle
7 - AFR
8 - Manifold pressure

Also have wheel speed on both front wheels. Getting around to doing the back ones as well....

You don't really need all that data - Frankly I did most of it as I got a lot of the sensors for free and I'm an engineer that can't leave well enough alone.
BMW 2000 M Coupe

zola1
Posts: 18
Joined: Sat Nov 19, 2011 4:47 pm

Postby zola1 » Sat Dec 24, 2011 1:02 pm

TPS ...No good idea...I haven't but will do now, where did you get the spare terminals for the DL1 multiplug ?....as this is a voltage in and i have used all the analogue inputs up on Dash2 i will put it as an input direct to DL1 ...make sense ?

I have a one switch that turns both the DL1 & Dash2 on....so reading your comment, i should not have a sw for DL1 (e.g wire it directly to +12v power) and swop the sw to Just turn the power on/off to Dash2 ?

You data in looks very similar to one i am aiming for


Dash2
1 - oil P
2 - oil T
3 - water T
4 - free (likely put in fuel level at some point....)

DL1
1 - volts
2 - water P
3 - free
4 - TPS
5 - Front Brake P did you add a b/p sensor for this or tap into oem ?
6 - Steering angle did you add a pot sensor for this or tap into oem
7 - AFR did you add a sensor for this or tap into oem
8 - Manifold pressure .. did you add sensor for this or tap into oem


...very cheeky to ask but i don't suppose you could send me your config as i am struggling to construct one without spending hours on it and then not being totally pc, literate loosing it ? Is it something that can be sent , this .dat file ?

When i tried first time the card reader had a moment and did'nt seem to save it then eventually it did.

I would like to get as much data as possible from the set up so will keep trying.....

many thanks

lots more q's will stop for the moment....[/b]

zola1
Posts: 18
Joined: Sat Nov 19, 2011 4:47 pm

Understanding the .dat file setup

Postby zola1 » Sat Dec 24, 2011 1:23 pm

On the data card provided with the DL1 there are two files :-

1). Internal with a Notepad RTCG001 with the :-
064 00579
066 00580
068 00579
070 00580
072 00579
074 00580
076 00579
078 00580
080 00579
082 00580
084 00579
086 00580
088 00579
090 00580
092 00579
094 00580
096 00579
098 00580
100 00579
102 00580
104 00579
106 00580
108 00579
110 00580
112 00579
114 00580
116 00579
054 00580
056 00579
058 00580
060 00579
062 00580


2). A file entitled RT809706 with two RUN files ......are these just used a programmed files to run the config and you do nothing with them or ??


When i had a first attempt at writing a config, the card reader had a moment and did'nt seem to save it then eventually it did.
...its a Dash.dat file but its only 12Kb ? does this sound correct ? ...please note i only put in a small excel spreadsheet for the equation of the x & y for the fuel level and 2 sensors saved from the drop down list for the WATER Temp and OIL Temp.

What i aiming for is a basic get started config and then add more sensors as i get more adept with the software......(long way off i feel :) ,,,but will get there.

Monkey on pc did not format SD card

cheers :oops:
Last edited by zola1 on Fri Dec 30, 2011 6:35 pm, edited 2 times in total.

osborni
Posts: 497
Joined: Fri Dec 07, 2007 9:08 pm
Location: USA, Michigan

Postby osborni » Sat Dec 24, 2011 3:46 pm

I'd use the DL1 as the primary sensor input device. I'd only use the Dash2 for overflow from the DL1 or for the slower (temps...) reacting sensors. I use pressures on the Dash2 only because I use my car on the street and don't turn the DL1 on for that.

I'd wire a separate power switch for the Dash2 regardless. In the 1% chance it flakes out (for me about every 4 to 5 track days it will do this once), it saves a lot of hassle for since I don't need to loose data, just the dash. I can re-boot it on the fly and not have to pit or have to deal with the DL1 re-booting and getting a split run file. Too much happening on track to worry about anything else.

Read the manual for how to load Dash2 config files. You really need to learn how to do this on your own. It's effectively a custom job regardless and my config files will be wrong for you.

Front brake P - added on my own. Tapped into the line going to the RF. A ~2,000 psi 0-5VDC Honeywell sensor off ebay. (autometer makes a decently priced sensor too). Need to know how to use a flair tool and how to do it so you don't hit the wall at the end of the main straight.

Steering angle. A string pot wrapped around the shaft inside the engine bay under the intake manifold. A Celesco SP1 with 25" pull. A SP2 would be better, but that's what I had.

AFR - An AEM wideband UEGO sensor and gauge. You need to drill and weld a bung into the exhaust system someplace. Easiest on the mid pipe just after the headers. Fit matters so you need some idea of what you are doing. The AEM outputs a 0-5 vdc signal.

Manifold pressure - added a MSI 0-30 ABSOLUTE pressure sensor. i.e., see level ambient pressure is ~15 psi - so you can get vacuum.
BMW 2000 M Coupe


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