Link G4X analogue input

[Stranger24]

I have a G4x plugin for my e36. I am trying to add a temp sensor for water and oil which output using ohm rather than volt to an temp 3 and and temp4 . I see and believe they only support volt output, am I right?

[Adamw]

Im not quite sure of your question so I will give a little background info that may answer what you are looking for, or if not, you can try giving more info. 

Most temperature sensors create a resistance that varies with temperature.  The ecu uses the resistance of the temp sensor to form part of a voltage divider circuit, so to the ecu it will see the signal as a variable voltage rather than a variable resistance.

The software calibration in the ecu to convert to temperature can use "ohms" or voltage.  

[Stranger24]

Thanks Adam

 

i have an oil and oil pressure which I am trying to get read by the ecu.

 

the sensors are part of my prosport premium gauge

 

i am tapping into the signal wire and connecting it to the expansion loom temp 3 which didn’t work

 

then I connected it to an volt 4 and used calibration table and that seems to work however I need to find the value of resistance to temp so value can be accurate

 

switching pull off resistor seems to make matter worse and it shows a very hight number, using 1k it shows ok and 10k more reasonable number

 

i hope I am making sense

 

i don’t know wha is the use of ground and 5v+ on the ecu so hoping I can het some clarification.

 

the sensors are two wires so npt I think they called , one ground and one signal so part of me thought I don’t need to connect the ground and 5v on the expansion loom

[dx4picco]

what is the sensor resistance at say, ambient 20°C?

[Stranger24]

I don’t have calibration table for that sensor. Tried with I think 4600 ohm which is 20 degree. Maybe it is wrong

[Adamw]

You will be better to fit a seperate sensor with a known calibration rather than guess or use trial and error. Temp gauges often use a 12V pull-up so the ECU wont be able to measure it, and with the gauges connected to chassis ground there is potentially a variable ground offset error as the electrical loads passing through the chassis vary.  

[Stranger24]

Thanks

 

issue is I have only two sensor so either have to let gauge go and just wire to ecu or use gauge and tap into it

 

you right ground is chassis and I am

Fairly new to efi tuning etc so I guess based on what you said if I try and get around accurate value still not worth it with ground being on chassis?

[Adamw]

There are surely many different options to fit an extra sensor, you wont be the first person to want a gauge and ecu sensor.    

[Stranger24]

On e36 I am using the head of the filter which can take two sensors

https://www.ebay.co.uk/itm/203909902316?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=mKGGNTToRYu&sssrc=4429486&ssuid=&var=&widget_ver=artemis&media=COPY

probably can buy splitter or ... but things gets complicated

 

alternative is get rid of all gauges, buy sensors and then read it on a dash like real dash I guess

[Confused]

I would sell your current gauges and sensors to someone who doesn't yet want to use a decent ECU, and instead have a bank of gauges, and you can use that money instead to put known sensors directly into the ECU, and get all the advantages of the ECU to perform protection strategies, and then maybe a single CAN gauge to flash up when there's any errors and the ECU has stepped in - this will be far better in my opinion than having a bank of gauges you're not looking at when you're pressing on, and can't react as quickly as the ECU can.

[Stranger24]

I invested £650 in gauges , yep you right.

 

Got it to work at the end but trial and error to work out the table

 

could someone help me understand what is the difference between an temp and an volt on expansion loom?

 

an temp expect ohm and an volt, voltage?

[Confused]

An Temp has an inbuilt resistor (fixed 1k for An Temp 3 & 4, selectable OFF, 1k or 10k for An Temp 1 & 2), designed for reading a temperature sensor, An Volt doesn't have a pull up resistor. You can use An Volt inputs as extra temperature inputs, but you need to supply your own external resistor in the wiring loom.

[Stranger24]

Thanks so using screenshot below where I see an temp 3 has resistor set to 1 and not able to change, that is pull up resistor by euc?

 

Re an volt, I also think the ecu provides the pull up resistor as when I change the value from 1 to 10k etc , it continued to work and values would change. in an volt are you stating the pull up resistor has no impact if there is no resistor on the wire? my experience is otherwise with an volt, I select diffrent resistor values and it changes the value displayed for oil temp when plugged into an volt 4

 

[Adamw]

9 hours ago, Aram said:

Re an volt, I also think the ecu provides the pull up resistor as when I change the value from 1 to 10k etc

No, the AN Volt inputs dont have an internal pull-up resistor, this setting is there for when you wire in your own external pull-up resistor, or when like in your case there is a pull-up resistor in an external device (gauge), the ecu needs to know what value pull-up is fitted as it is needed for the calculation to convert ohms into volts/temperature.  

This is why I suggested fitting an independent sensor with known data.  Right now you dont know the pull-up resistor value that is inside the gauge, you dont know the voltage that the gauge is passing through the pull-up, and you dont know the calibration curve of the sensor.  You will have to build your own calibration curve for the sensor, you can use ice water and boiling water for 2 known points, then possibly calibrate against the displayed gauge values at higher temps if you trust it is accurate.    

[Stranger24]

Makes sense thank you.

 

i know understand, prob when I change the pull up resister value it changes value because of what is used on the gauge and me thinking it is ecu

 

thanks again

 

 

[Stranger24]

Hey guys

 

i managed to sort this

 

both temp and pressure connected to an volt and it is now reading within1-2 degree / psi of the gauge and I am ok with this

 

when I used the an temp, it won’t work as I guess the gauge has resistor and an temp 3 and 4 have a 1k fixed resistor so it switches the gauge off .

 

i guess only way to wire my fuel pressure and exhaust temp is to use more an volt and send ecu to link to solder the extra pins for me

 

[Adamw]

Have you already used AN Volt 3 and AN Volt 6 on the main header?

[Stranger24]

An volt 3 shows as nb oxy and an volt 6 nothing on current ecu so nope.

 

i need to find an volt 3 wire on main wiring (pin 13) and then wire the wide band to and ground of wide band to expansion loom. Is that right?

 

re an6 it is pin 41 so can do fuel pressure

 

that leave me 1 an short for exhaust temp

 

i see the pc link software says we have 12 an leading me to believe link can solder 6 more wires for an volt in. 

 

[Stranger24]

another question, on pc link software how can you define something which is not there already 

 

for instance I want to add exhaust temp , can't see an option to add or rename exhaust pressure.  when you click on input pins, you can't define it. 

 

it seems you first have to define it under analog input before you can assign it to a pin

 

 

[Adamw]

Go into the GP input folder. 

[Stranger24]

Thank you Adam, was very simple and should have played with it more 

 

out of interest what does gp stand for as I also see gp in limit for customised rpm

limit

[Stranger24]

Spoke to Link tech to get my ecu dispatched to solder an volt and aux. he said he will try and do 5 an volt and 2 aux minimum or 4 aux if he can because he doesn’t want wires to cross and ….

 

guy was very helpful however something is annoying me. Link advertise the ecu with 12 an volt and apparently only 11 is available.

 

he mentioned an volt 7 is not available and link advertise the ecu having 12 an volts .

my ecu is g4x plug in e36.

 

why would link advert a misleading info?

Math below:

There is 2 an volt on expansion loom, 4 on board / main wiring which leaves 6. The guy on link tech was adamant an volt 7 is not available therefore we only have 11 volt not 12.

 

little annoyed

[dx4picco]

2 hours ago, Aram said:

guy was very helpful however something is annoying me. Link advertise the ecu with 12 an volt and apparently only 11 is available.

little annoyed

look correctly: https://linkecu.com/wp-content/uploads/2020/07/ECUCatalogue.pdf

"† Check specific pinout for number of I/Os exposed"

the point of plugin ECU is also to have affordable ecu when the car doesn't need all the I/O, because the price of them is also related to that.

for older cars with little I/o need, it would make no sens to only offer a version with all the I/O possible from processor, at double the cost of the actual product.

[Stranger24]

Right and the manual has no mention of an volt 7. I guess Link expect one to know the unknown and not rely on advert from what it seems

 

i checked the manual and there is no mention of pin an volt 7 on the manual so really that small print means contact tech support!

[koracing]

AN Volt 7 is used on several other plug-in ecus so not sure what's the deal if it's specific to the board configuration of the E36x plug in.  Perhaps there is hardware in the way or something, but I doubt it's an ecu limitation.