My DCT conversion to M3 GWS/FLASH

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amg6975

Lurker
Oct 27, 2019
21
Actually, it is another hardware solution, but what you are proposing sounds better.
Can you fill me in a little more? Via PM if you’d like. I don’t want to duplicate efforts if it’s not necessary. I’m still thinking I may just chuck a 3.08 in until I do the whole M3 swap.

My solution would take a bit of development so we’re probably a couple months out from anything solid.
 

amg6975

Lurker
Oct 27, 2019
21
I’d also be curious to just sit on the PT CAN bus and as soon as I saw the RPM request packet just immediately write the same packet with a modified value and see if it would override the previous one in the ECM. Then it could just be plugged in anywhere and wouldn’t have to pass the rest of the bus traffic.
This could very easily be done with the Arduino some of you are already playing with.
 
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NoQuarter

Captain
Nov 24, 2017
1,168
Indiana, USA
I have my Z4 wired right now catching pt can traffic to try and figure out the tcu identifier.

Unfortunately I am laid up yet again this year - this time shoulder surgery in my dominate arm so the car is just sitting at the moment.
 

amg6975

Lurker
Oct 27, 2019
21
I just had another idea that could blow this market wide open. I don’t think I’m 100% ready to go public with but if any of the main guys involved in this project want to talk about it, PM me.

I’ll need to figure out if my last idea about just “overruling” the TCU’s RPM request will work to know if my new idea will work.
 
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Imap777

New Member
Oct 4, 2019
9
Yeah, pass all other CAN messages through unchanged, hijack and modify the RPM request messages. A custom board, ideally with OEM male and female connectors, and maybe 100 lines of code.



I definitely think the MHD map modification would be a far better solution but it could be done cleanly with a custom hardware solution. The latency wouldn’t be an issue, CAN is very slow compared to how fast the messages could be passed through or modified and retransmitted. We’re talking micro seconds.
You mean the LC RPM request?
 
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Imap777

New Member
Oct 4, 2019
9
No. The RPM request for the next gear to handle rev matching
I can find those requests, as I am interested to adopt the dct on gts to 3.08. Not like I have an issue (3.15/3.08 difference seems to be within adaption range), but I am not quite sure my ina0s holds anything. More over, I can't test it, as its not something u can really *feel* during GTS up-shift (too fast), and down shift is really smooth, may be just sometimes it jerks, but I have never driven the stock DCT car.

Any idea how can I check if my manipulations are any good? I was thinking of MHD logging and seeing the RPM on the shifts, but that wouldn't be any reliable.

Guess I will just take it to the extreme values, like down-shifting drop to 900 rpm for sake of proof. Think the RPM back-feed (from DSC or KOMBI, whatever DCT cares about) should be hijacked too, as TCU won't see RPM's it requested, thus going all nuts.
 
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NoQuarter

Captain
Nov 24, 2017
1,168
Indiana, USA
I still have use of just one Arm and I want to swap out the shifter.

Does the parking cable get removed from under the car or is it done from the top?

I need to figure out what help to line up.
 

amg6975

Lurker
Oct 27, 2019
21
Nice!

So I guess I didn't realize that the parking brake lock was actuated by the GWS. There's a LIN bus connection to the TCU for this, but I thought the GWS was sending the commands but it must be receiving commands from the TCU. Interesting.
 
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NoQuarter

Captain
Nov 24, 2017
1,168
Indiana, USA
Nice!

So I guess I didn't realize that the parking brake was actuated by the GWS. There's a LIN bus connection to the TCU for this, but I thought the GWS was sending the commands but it must be receiving commands from the TCU. Interesting.
I used some poor words here I think.
Not talking about the parking Brake.

I am referring to the parking lock of the transmission. When you hit P on the shifter or in the case of the M3 when you turn off the ignition.
 

NoQuarter

Captain
Nov 24, 2017
1,168
Indiana, USA
Got the easy part of the pinout swapped over. Next is the extension for the parking lock connection and adding new wires for the drive logic button.

I'll also add in a semi-permanent pt-can connection for longer term easy data capture
 
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silverstreak18

Specialist
Jan 3, 2018
89
To those of you who have successfully completed this conversion how is it driving with the final drive change to 3.15? What is highway cruising like? Taking off from a stop compared to stock diff?
 

amg6975

Lurker
Oct 27, 2019
21
Got the easy part of the pinout swapped over. Next is the extension for the parking lock connection and adding new wires for the drive logic button.

I'll also add in a semi-permanent pt-can connection for longer term easy data capture
Awesome! One thing I just came across as I took things apart is the car is apparently super pissed if the Sport button is unplugged. Even with the key out and everything off it was beeping about a shifter issue. I have to investigate where that connection goes.

To those of you who have successfully completed this conversion how is it driving with the final drive change to 3.15? What is highway cruising like? Taking off from a stop compared to stock diff?
Curious as well, but I imagine it'll be fine. I just made a deal for a 3.08 I'm going to install until I do the full M3 conversion.
 
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