Potential C125/C127 Buyer, couple questions.

[Nick411]

Hi guys, I have a couple questions surrounding the C125/C127 dashes that I can't seem to find answers to elsewhere. So I apologize if most of this is basic knowledge.

I'm currently looking into digital dashes for my '02 WRX street/track toy. At first I was just looking at the AiM stuff as it's much cheaper ($1500-$2000CAD cheaper for the equivalent setup due to logging, I/O, and LTC costs) and everyone around here uses it. Motec stuff is left for the purebred race cars. However I started playing around with both the AiM and Motec dash configuration software and the AiM dashes are just too constrictive for my liking and are locked into what you're given whereas the Motec stuff is virtually limitless in what you can do with additional software licences and upgrades. Even the basic out of the box stuff makes the AiM look childish. Plus AiM seams to have a fetish for binder plugs *shutters*. This swung me massively over to the Motec dash. Which made my plans for going with an M130 down the road a little more seamless.

Anyway, my main questions are:

1) ECU communication. The AiM dash communicates to any Subaru ECU via the K-Line on the ODB2 plug. Which makes things very easy when it comes to ECU connection however, no where have I found the C125/C127 to do this and to my knowledge they only communicate via CAN (correct me if I'm wrong). Since my WRX is a MY2002 it doesn't use the MY2008+ CAN protocol. It uses ISO 9141-2/ISO 14230-4 via the K-Line IIRC. How would I go about connecting the dash to a non-CAN ECU? Or does this ECU have CAN, just not the current protocol that everything MY2008+ uses?

The AiM dash is very limited in what it can read via the K-Line which I find odd since the COBB tuner can read everything on the ECU via the OBD2 plug. The connector for the COBB handheld has pins for the K-Line (pin 7), CAN pins (pins 6+14), and the Subaru Select Monitor timing pulse pins (pins 9+11). The CAN pins are more than likely just there for the MY2008+ CAN based cars, but I could be wrong. So I'm a little confused as to how to go about connecting a C125/C127 to this ECU.

2) Screen size. I plan on putting it right in front of the stock cluster using the surround as the mounting point as opposed to on the steering column. One of the other reasons I prefer the Motec dash to the AiM dash is I need the 7" screen to clearly see the readouts because the font size is small whereas I hope I can easily get away with the 5" screen on the Motec since the font size is much bigger. Anyone have their's mounted at this distance? Do I need the 7" or can I get away with the 5"?

I have a few more question regarding some more complex math channels but I'll get into those if I decide to go this route.


Thanks.

[David Ferguson]

I think you correctly understand the market. AiM has supported the K-Line communications because it is necessary for their market, however they will only do the basic stuff that can be done easily. Cobb is able to go beyond what is easily obtainable via ODB-II communication protocols which is why they can read additional information (they might even be running their own code in the ECU).

The MoTeC dash/loggers are more oriented to a dedicated race car or cars with stand-alone ECUs. MoTeC has never had a real need to support ECUs that only do ODB-II through K-Line. I think there might be a market for a device which provided access to factory ECU and produced a standard CAN ECU stream. It would take a lot of R&D effort (and access to cars for investigation) to support lots of cars, and customer would not want to pay much for what they would see as an "adapter cable".

When we install MoTeC dashes onto cars (mostly race cars) that don't have an ECU data stream. We just end up putting on sensors for things we want to monitor (oil pressure, coolant temperature, oil temperature, fuel pressure, throttle position, lambda, etc). Lots of race engines still use carburetors and we have to do this for these anyway. Sometimes we pick up a tach signal from a coil or injector, or actually put trigger wheels for a perfectly clean signal.

Some times we can "share" a sensor with the factory ECU by splicing into the signal wire to measure the voltage. Throttle position and gear position on motorcycle engines are examples of this. I've even calculated fuel consumption by measuring the injector pulse width and calibrating this for enduro racing.

[Nick411]

Ok, figured these were tailored for use with CAN. The expander I'd need to share sensor wires with the ECU would put Motec out of budget for me in the dash department as long as I still have the factory ECU running the engine. Damn 15 year old ECU...... Maybe down the road with the M130 .

Thanks for the clarification!

[David Ferguson]

MoTeC showed a low-cost 6-channel expander at PRI last December,

[Nick411]

Hmmm.....depending on when that comes out that might change things. I'll keep my eye out for it.

[Nick411]

I was browsing the Documentation section of milspecwiring and found that Motec has a K-Line to CAN converter (#61140). It does say that it's meant for Yamaha and Kawasaki jet skis, but the K-Line protocol is the same (ISO 9141). In theory could this work? Or am I trying to build a bridge to nowhere?

[David Ferguson]

The KTC only transmits KLine data to the dashes in PWC applications. I have checked if this could be used to receive K-Line data and was told it can't.

[stevieturbo]

Maybe AIM's MXG might be the best option for what you have currently ?

https://www.aimtechnologies.com/car-rac ... sh-logger/

Or fit a proper standalone ecu to the car that can then transmit all relevant data to any dash display ?

[adrian]

The biggest problem with these situations is the amount of time required to come up with a decent solution. The OBD protocols (including the CAN OBD-II that our dashes can read) are all designed around emissions and diagnostics. The biggest problem with this is that the information you can get varies manufacturer to manufacturer and the update rate is often quite slow when compared to the vehicle high speed buses.

To get high quality information it means you have to reverse engineer the vehicle comms bus, this obviously takes up a massive amount of engineering resources so we have to carefully select which vehicles we do. This is normally based on demand and because of the market we aim for it usually comes in the form of a replacement ECU capable of running the whole vehicle including the other electronic systems.

The C125/7 dashes do have analogue inputs (6 AV and 2 AT) that are enabled with an upgrade code, you would only need to purchase an expander if you needed to wire in more sensors than that.

Having an M130 would certainly make it much easier, it transmits hundreds of channels at high rates via CAN that can then be displayed/logged by a dash.

[Nick411]

Maybe AIM's MXG might be the best option for what you have currently ?

https://www.aimtechnologies.com/car-rac ... sh-logger/

Or fit a proper standalone ecu to the car that can then transmit all relevant data to any dash display ?

Yeah that was the initial one I was looking at as it's basically a PnP system for me aside from the added sensors I want. Since it's becoming clear that unless I want to spend endless amount of money needlessly to make a Motec dash work while I have the stock ECU running the show it's more than likely what I'm going to go with for now.

The biggest problem with these situations is the amount of time required to come up with a decent solution. The OBD protocols (including the CAN OBD-II that our dashes can read) are all designed around emissions and diagnostics. The biggest problem with this is that the information you can get varies manufacturer to manufacturer and the update rate is often quite slow when compared to the vehicle high speed buses.

To get high quality information it means you have to reverse engineer the vehicle comms bus, this obviously takes up a massive amount of engineering resources so we have to carefully select which vehicles we do. This is normally based on demand and because of the market we aim for it usually comes in the form of a replacement ECU capable of running the whole vehicle including the other electronic systems.

The C125/7 dashes do have analogue inputs (6 AV and 2 AT) that are enabled with an upgrade code, you would only need to purchase an expander if you needed to wire in more sensors than that.

Having an M130 would certainly make it much easier, it transmits hundreds of channels at high rates via CAN that can then be displayed/logged by a dash.

The only issue I have with getting an expander to make a Motec dash work is it would end up costing over 2x what the AiM dash and related items would. So waiting until I have an M130 would make a lot more sense as I also plan on getting a PDM/Keypad and basically running as much of the car off of the ECU and PDM as I can get away with and still be street legal in my region. Having all of that on the same CAN Bus makes it a whole lot easier.