MECS tinkering
 

So coming from Nissan, we have it pretty good with the pre OBD-II diagnostics. There are several Consult port software programs available to obtain and even edit the system parameters.

It looks like there is not a commercial offering for FD. But I can tell there are some smart people who've made quite a bit of progress.

https://www.rx7club.com/3rd-generati...iagnostic+port

Data interface with stock ECU - RX7Club.com

I was thinking maybe it would be worthwhile to write a proxy that would convert the MECS output codes into OBD-II PIDs. There are all kinds of OBD-II dataloggers now and the latest OBD-II bluetooth stuff seems incredibly cheap.

I have a few arduinos laying around so I figured I would take a crack at it. I need to figure out if that will be powerful enough or if I need to move up to something like a Raspberry Pi.

I'd be curious to know if any one else has an shared experience in this space before I get too far into it.

Jim

P.S. Where in the world do I find the 17-pin diagnostic connector? I'm sure I can jumper it for prototyping, but at some point I would like to make a decent cable.

Sample rate will be very slow...

There were one or two devices from Japan that plugged into the underhood diagnostics port - I think Techtom had one, and RE-Amemiya had a limited edition Greddy device that normally used a USB port but plugged into the underhood diag port.

While it would be cool, and huge hats off to you if you could figure it out, many people just go with a PowerFC that gives them plenty of data. You can see all the inputs from the sensor check screen, watch sensors in the gauge mode, etc.

I'm just not sure if what is coming out of that port would be useful or relevant.

Dale

I agree.... seeing as how USDM FD's use an 8-bit ECU, trying to make a device that reads data from the Diagnostic port in the engine bay is rather moot.


Most people simply use a PowerFC to read data on the fly and datalog.

Doing so on a stock ECU is pointless, even with trying to attempt to reflash the stock ECU.

In any case,
I do recall someone trying something similar but went about it in a different way..... I wish I knew where to find that thread because maybe the both of you could join heads and see what you can come up with.

I follow what you guys are saying, the PowerFC would be the way to go for serious tuning.

My goal is mainly to output the currently available diagnostics. If i could find a reasonably priced techtom, that would be ideal. I have one for my 300ZX and it serves it's purpose quite well.

For me at least, I think 4-5 samples per second would be more than enough to measure the available parms.

Jim

Look at it this way. That diagnostic port was designed for handheld dealership scantools from 20 years ago. It was never meant for tuning. You would have to read directly from the memory addresses inside the ECU. You need special hardware.

4-5 samples per second, not going to happen from the diag port.