Sniffing the CAN bus

meinolf wrote:

So I wonder why you suggest that reading OBD data while driving might not be a good idea?

I've also logged many hours of OBD data while riding my GRiSO, with both GuzziDiag and ScanM5x. I too wonder why it would be a problem. Well, I know it's not a problem...

I have done it many times, especially while getting a map built - no issues!

Hi all, I'm intrigued and am willing to help if I can. I am an electronics microsystem designer with many tens of years of embedded C (I feel old) experience and can also turn a PCB if dedicated hardware is required. 'Cos of work I don't have a huge amount of spare time - but if you want to ping me any specific hardware/embedded questions I'll try to help. I also have a suite of tools that make Windows PC<=>Arduino comms really easy.

Of course I also have an ageing GRiSO whose life span I'd like to extend.

Guys, you are overthinking this. Alberto, I strongly recommend you get over your concerns about deactivating lambda. If you've had some "engine work", then you should look at a target AFR of 0.9, which in my real-world tests & experience is optimal for the 2V engine. For the 8V, it's 0.87.

Furthermore, remapping and AFR logging is outside the scope of this thread, and I would please ask you to start a new one. This thread is about a viable alternative for the stock dash for the simple requirement of air pressure data.

Thanks!

It seems that the air pressure sender does not do a great job and running without it will make minimal difference.
That said it would be useful to be able to install a well calibrated upgrade if running without the stock speedo.
I made quite a lot of modifications to my GRiSO while looking at the option of running a different unit
and can't go back to square one to check stuff.

I presumed, wrongly, that the café racers based on Grisos with a different instrument would have replaced the ECU.

On finding that Grisos will run without the original speedo connected I'm wondering if anyone else who has done so can give a comprehensive rundown of what needs to be modified, warning lights, systems etc, and what systems are lost, the electronic part of the ignition switch system for instance.

On that issue I feel that only having a key system without a chip installed and having a concealed switch to isolate the electrics is a better way. I use a resettable circuit breaker that isolates everything but the clock in the Acewell speedo.

During my next major work on my GRiSO I'm going to tackle installing a sender for the fuel gauge circuit of the Acewell, it would be great to have a fuel gauge rather than a warning light that might not work or having to fill the tank every time and watch the mileage to calculate how much fuel is left in the tank.

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Triking (CARC T4) stuff & their technical sections/forums are littered with addressing this type of problem - they seem to use a generic replacement for the air pressure sensor that works with their modified EFI harness & talks to std IAW 5AM ECU via CANbus

anyway & in case you didn't look there yet; here's a link or two

Triking T4 tech stuff

Triking T4 EFI wiring

jtdesign make the 'customised' air pressure sensor that talks to the ECU Discussion on APS-1

That was an interesting read.

But I don't understand how in "Basic Operation" the air pressure sensor can be wired into the CANBUS pins?

V-20 CANBUS H-line To air pressure sensor APS-1 pin 3
V-29 CANBUS L-line To air pressure sensor APS-1 pin 2

Does the Triking engine map change the 'configuration' of these ECU pins?

I also can't find any model number or characteristics for APS-1. Looked through their 'shop' but didn't see one.

Clancy wrote:

That was an interesting read.

But I don't understand how in "Basic Operation" the air pressure sensor can be wired into the CANBUS pins?

V-20 CANBUS H-line To air pressure sensor APS-1 pin 3
V-29 CANBUS L-line To air pressure sensor APS-1 pin 2

Does the Triking engine map change the 'configuration' of these ECU pins?

I also can't find any model number or characteristics for APS-1. Looked through their 'shop' but didn't see one.

No, the pinout can't be changed by the map. Those pins are the CAN bus lines on the 5AM. The APS-1 probably reports itself as the correct node, and sends the pressure data on the correct address as the ECU polls the node.

Great info, I had a quick look, but will do more reading when I get home

beetle wrote:

The APS-1 probably reports itself as the correct node, and sends the pressure data on the correct address as the ECU polls the node.

Ok. So a CAN bus sensor, not a basic anaologue output sensor. Sorry.

No Craig, it's a network node and when addressed responds with an appropriate response. Think can, lin, tcp/ip, profibus and the like: "ask me a proper question and I'll give you a proper answer"

The whole electronics bit is black magic to me.

The same response that many give to clearcoat carbon fibre work, which for me is easy.
Each to his own.

Great to read that there is a solution to replacing the air pressure sensor though.

As I evolved customizing my GRiSO I replaced the left hand switch assembly to give conventional, off,
parker, headlights where the mode switch is on the original switch, which of course is defunct if the original speedo / rev counter / circuit board is disconnected.
I also found their idea of putting the horn button above the indicator switch arse about.

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I ran a heavy duty cable from the battery through a circuit breaker to two relays for dip and main beam on the headlights. The relays triggered from the new switch. I took the high beam led dash indicator from the high beam output from that relay.

I installed new wiring and indicator module again triggered from the new switch and took the left and right led dash indicators from the output side of that module.
I personally don't like one dash light for either indicator.
I prefer separate left and right dash indicator lights.

The side stand switch is off when the stand is down on when it's up.
The reverse of what is needed for a dash indicator light. The solution is to use the signal from the switch to another relay and have that making a circuit to the dash light when the stand is down.

It's quite possible that if I understood the inputs and outputs from the ecu that I could have tapped into those, but as I wrote it's Greek to me and the last thing I needed was to wreck my ecu !

This all works but maybe someone who has more understanding of the ins and outs of the electronics has an easier solution ?

What I'm hoping is at the end there will be a comprehensive "how to" regarding replacing the original speedo.
I can see it being a real problem for those with a failed unit in future as they become rarer or too expensive.

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This arrived today! Yay.