Onboard computer for VW T3 and earlier

[thenomadcat]

Hi guys,

I was curious if anybody knows any successful projects to get an onboard computer for VW T3.
Is anyone interested in such a thing?

I've recently started working on one powered by an Arduino. The first phase is to read, display and record coolant temperature, oil temperature and oil pressure. Almost done with the coolant temp, the oil temp will be much easier and faster (have been working for a week now).

If there is interest, I'd like to share the whole thing here and maybe get some feedback.
Not looking to sale anything, it's going to be freeware

Andrei

[Mw999]

Hi Andrei,

It’s something that I’m interested in, I’m hoping to do mine using the OBD port on a Subaru conversion

I think unfortunately that oil pressure isn’t one of the parameters that OBD looks at, I’m still looking at options and I’m not keen on the displays that some of the off the shelf option use

Martin

[thenomadcat]

Hi Martin,

Any analog sender will do the same, the resistor inside will go up or down.
Theoretically you need to measure the voltage from a voltage divider with the pressure sender acting as one of the resistors. Rounding and error corrections are needed, but it is the same process as measuring temperature.

What options do you have?

Andrei

[Mw999]

Hi Andrei,

I was hoping to keep it simple and use a Bluetooth OBD transmitter to either and iPhone app, dedicated over the counter hardware like scan gauge or I think Garmin or Tom Tom used to do a sat nav that could access the OBD data.

This way any fault codes would flag up straight away, on another classic car I’ve got I’ve found I rather like seeing oil temps and pressures as a way of engine health monitoring too

The engine is a legacy 2.5 SOHC, google info is limited but I think oil pressure in particular is a binary switch so I don’t think it will be straightforward for me to achieve what I want

Martin

[thenomadcat]

Hi Martin,

If you have no oil pressure info (except the red blinking light that says it's to late), yes, for sure there is only a switch somewhere in there. VDO has a 0-5bar sender (https://www.brickwerks.co.uk/vdo-sender ... m10x1.html" onclick="window.open(this.href);return false;) that integrates a 0.25 bar switch. Not sure what the working values are for the Subaru engine, but if you can fit this M10 in place of the actual switch you have or create a T pipe for it, half the problem is solved.

This is the sender I'm going to use and I'll make available all the required hardware and data to read it.
You can use any pressure sender as long as you have the resistor/pressure reference table.

Andrei

[bobby-gg]

I'm running a Tdi in mine so I've got a OBD port and as such I'm running a scanguage in mine which I find invaluable in displaying my inlet air temp, water air temp, rpm and mph (speed sensor fitted into speedo head.

But I also monitor exhaust gas outlet temp, using a k type t/c, converter and digital display in a dash switch blank as a simple monitor



But I've been thinking of expanding the system to monitor further temps by using an arduino, and found the guy's below an interesting system but think that the screen will be slightly small

https://www.jameco.com/Jameco/workshop/ ... anner.html" onclick="window.open(this.href);return false;

Food for thought

Rob

[chrisdc]

@bobby-gg I'm impressed by the display in the spare switch blank - where did you source the display from?

I'm also developing a computer powered replacement for the electronic choke on my 2l Aircooled engine. A byproduct of the project will be a cylinder head temperature monitor - although this may be a little scary to see!

I've also noted the recent post on "Replacing the dashboard plastic PCB" has references to PC manufacture in China (@CJH) - may be worth bring that knowledge/ experience to this discussion too.

Chris

[Arripay]

Very Interested in your project Andrei, would love to get something like this working!!

[bobby-gg]

@bobby-gg I'm impressed by the display in the spare switch blank - where did you source the display from?

I'm also developing a computer powered replacement for the electronic choke on my 2l Aircooled engine. A byproduct of the project will be a cylinder head temperature monitor - although this may be a little scary to see!

I've also noted the recent post on "Replacing the dashboard plastic PCB" has references to PC manufacture in China (@CJH) - may be worth bring that knowledge/ experience to this discussion too.

Chris

Chris, it's a 3 segment led display from RS, the outer is a perfect fit into the switch blank, but the pcb behind needed some serious amount of filing down to get into the inner hole.

I'll look through my old receipts and see if I can find the part number

Rob

[chrisdc]

@bobby-gg I'm impressed by the display in the spare switch blank - where did you source the display from?

I'm also developing a computer powered replacement for the electronic choke on my 2l Aircooled engine. A byproduct of the project will be a cylinder head temperature monitor - although this may be a little scary to see!

I've also noted the recent post on "Replacing the dashboard plastic PCB" has references to PC manufacture in China (@CJH) - may be worth bring that knowledge/ experience to this discussion too.

Chris

Chris, it's a 3 segment led display from RS, the outer is a perfect fit into the switch blank, but the pcb behind needed some serious amount of filing down to get into the inner hole.

I'll look through my old receipts and see if I can find the part number

Rob

Thanks Rob. Had a look at RS and they have a range of 3 digit LEDs. Now that you've put me on the right track, I'm sure I'll find something that is suitable. But if you do find a part number that would be most helpful.

Chris

Sent from my LG-H815 using Tapatalk

[thenomadcat]

I've been away for a few days, but I'm back working on this.

I don't think I'll be using an LCD. Most probably I'll have the data written to an SD card (will double as a data logger) and send it over Bluetooth to my phone.

The water temperature is done. After 3 nights I have managed to properly calibrate the VDO sender using a fairly accurate digital sensor. I'm very pleased with the results. I hope it still works when I put it on the car.

The oil temperature is also almost done. Does anyone know the "correct" oil temperature? I have the 1.7 KY. Does the temp differ for other engines?
I know the oil temp for setting dynamic timing is 80°C, but is it also the normal working temperature? Can't be right, seems cold.

Thanks,
Andrei

[bobby-gg]

[/quote]Thanks Rob. Had a look at RS and they have a range of 3 digit LEDs. Now that you've put me on the right track, I'm sure I'll find something that is suitable. But if you do find a part number that would be most helpful.

Chris

Sent from my LG-H815 using Tapatalk[/quote]


Chris, I may of lead you up the garden path - it's actually a 4 digit 4-20mA input display that I used, handy because the converter I used is 4-20mA output.

I'm fairly sure it was this on I used

https://uk.rs-online.com/web/p/digital- ... s/2549181/" onclick="window.open(this.href);return false;

It's a tight fit, and you'll either have to file out the dash blank a touch, or the pcb, I went with the latter and the pcb is down to the pots on the board!

Rob

[bigbadbob76]

Interesting project TNC.
I'm thinking more along the lines of a data logger that would record temperatures and pressures and maybe RPM at regular intervals for fault diagnosis if I get a problem.
This would need a memory card (SD card?) for logging the data so I'd be looking at maybe a Raspberry Pi but from experience they don't like being crash stopped with the power just dropping out
so I'd need some sort of soft shutdown circuit.

Or maybe using an arduino to generate a serial data string every so often that could be logged to an "Openlog" logger or read in real time.

[stigma]

Interesting project TNC.
I'm thinking more along the lines of a data logger that would record temperatures and pressures and maybe RPM at regular intervals for fault diagnosis if I get a problem.
This would need a memory card (SD card?) for logging the data so I'd be looking at maybe a Raspberry Pi but from experience they don't like being crash stopped with the power just dropping out
so I'd need some sort of soft shutdown circuit.

Or maybe using an arduino to generate a serial data string every so often that could be logged to an "Openlog" logger or read in real time.

Arduino can easily log data onto sd card.

[bigbadbob76]

Arduino can easily log data onto sd card.

My arduino is a nano so I might need a seperate spi/SD module rather than a shield.
I'd want serial output too, so I can hook up a pC for real time data.

Has anyone figured out the pinout for the TDC sensor that's used for VW diagnostics but not normally wired?
Presumably power, ground and signal output.
This would give RPM pulses I think without using the noisy ignition signal.
Lots to think about, thanks for starting my train of thought tnc.

UPDATE- the TDC sensor seems to be an inductive pickup, only two wires used and they're interchangable. a quick poke with a meter will tell you which wires are connected. I'll scope mine when I get a chance.