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foxdie
23-06-2017, 10:24 PM
Hi folks,

Well, you all know me by now, I believe in sharing knowledge. This thread is a dump of my progress for hacking the Pre-facelift automatic ECU.

Phase 1 - Download the ROM from the Auto ECU
Phase 2 - Build a definition file
Phase 3 - Make a change and test it

Phase 1 was completed a couple of weeks ago, with a crocodile clip and some bare wire I was able to successfully download the ROM from the Auto ECU using an Openport 2.0 cable.

Phase 2 is now in progress, I've spent about an hour looking at this so far and this is what I've learnt;

Here's what we know so far;

* Although probably common knowledge - the pre-facelift autobox ECU's also have a 7201 chip inside - like the PFL engine ECU
* The 7201 ECU seems to favour some little endian (https://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Data/endian.html) tables whereas all the others seem to use only big endian tables (this threw me at first)
* The 7202 and 7203 ROMs are seemingly identical

Well tonight I crossed a milestone; I've successfully located the throttle position and first -> second gear shift point tables in the 7201 gearbox ECU /Banana

Here's a comparison between the PFL and FL tables (PFL is at the front, FL is behind it to the right).

77859

We can see that between PFL and FL, Mitsubishi changed the shift points, the PFL holding gears longer and the FL shifting up sooner.

More to come, watch this space :thumbsup:

foxdie
24-06-2017, 12:43 AM
Second update!

Definition is done as far as I can get it using BCX templates as hints to find locations. They can be found in the Definitive ECU ROM repository (https://www.clubvr4.com/forum/showthread.php?69931-Definitive-ECU-ROM-repository) along with the others.

Couple of things to note;

* There were some oddities in BCX tables (I'm sure he did the best he could, it's a huge headache looking through hex) and those have transferred across, there are a couple of tables that don't seem right
* The MUT periphery table looks vastly different, presumably because it's a different ROM entirely

Another thing too, after bouncing some ideas against Confused and Nick Mann, I'm wondering if the unknown shift point tables are interpolated for the INVECS driver style learning. Here's a screenshot;

77860

The above is 2 pairs of tables, the ones on the left are the 1st -> 2nd gearshift tables, the ones on the right are 2nd -> 3rd.

It's widely known the main engine ECU has 2 fuelling tables; high octane and low octane. It interpolates between these depending on how much knock affects the octane rating (0-100). My theory is that, depending on how aggressive you are driving, it interpolates between the "known" and "unknown" table to choose it's shift point, with a variable (lets say 0-100 again) relating to driving aggressiveness.

I am thinking the "known" table is for hard driving, the "unknown" table is for gentle driving;

The harder you drive, the closer to the "known" table the gearbox shifts, holding gears longer.
The softer you drive, the closer to the "unknown" table the gearbox shifts, shifting up sooner.

I'm not sure. It's late, I'm off to bed. For now, at least we have something to play with :)

Davezj
26-06-2017, 07:32 PM
sound like you have been hacking the **** out of this.

looks great.

orionn2o
27-06-2017, 11:12 AM
Excellent work Jason :)

foxdie
27-06-2017, 12:39 PM
Thanks chaps :)
Confused has been helping out a lot and will help test some of the tables.

I've also approached someone to see if they can help us change the code to add torque converter lockup in 3rd gear too.

Confused
27-06-2017, 12:45 PM
Yep I'll be testing some stuff out over the next few days, watch this space :)

orionn2o
27-06-2017, 12:55 PM
Ideally you want to be able to set a nice drag racing style torque converter setting :)

foxdie
28-06-2017, 10:05 PM
Question, has anyone mixed a early facelift autobox ECU (with the additional speed wire) with a late facelift auto gearbox (without the additional speed wire), or vice versa?

If so, were there any issues?

( Davezj adaxo Wodjno you guys may know this? )

Davezj
30-06-2017, 08:55 AM
I am not sure.
I think most of the swap that have worked are old PFL boxes with PFL ECU and these seem to be able to be fitted to any car.
I do have never old FL auto box and ECU in the back of my shed (buried under a load of stuff) and that configuration did not work for Nev in his PFL not sure if the box and ECU is early or late.
Nev or nick Mann would have more info on this.
elnevio Nick Mann

Sent from my MI 5s using Tapatalk

Confused
30-06-2017, 10:50 AM
Davezj if you get a chance to dig out the box and ECU, we'd be very interested to know the part numbers and processor type :)

Davezj
30-06-2017, 11:37 AM
Easier said than done.
I can't get into my shed without taking stuff out of the door and it is right at the back with 10-12 feet of stuff in-between.
I think all the numbers from the box and ECU are already recorded on the forum somewhere, as Nev tried to get the box and ECU to work in his car but gave up and removed it. He fitted a PFL ECU and box I believe.
Which seems to be the only off the shelf combination that is proven to work in a PFL car.
Although my silver vr4 originally had a second gen box ( no external filter and OWC) with a plastic case ecu.
That is a 1998 car.
I have probably recorded those numbers on here as well.
I did a lot of searching for the correct pairings of box and ECU.
There are tables of the results somewhere.
elnevio will know what the thread was called or some specific key words to search for it.

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foxdie
02-07-2017, 10:11 PM
Posting an update.

Earlier today we successfully reflashed a pre-facelift gearbox ECU and improved shift time by 20%.

Video demonstration;


http://www.youtube.com/watch?v=x-sqwbLZ-h4

Keep in mind this car has a boost leak. There's potential for more :)

rajvr497
03-07-2017, 02:13 AM
Great work Jason...
more to come????

Confused
03-07-2017, 07:45 AM
Yes, we certainly hope so!! This has definitely whet our appetites!

Anderz
03-07-2017, 10:36 AM
Excellent, good work! A bit off topic but have you found how to control the TC lockup, or is it found for the FL Auto?

Confused
03-07-2017, 10:37 AM
Not yet, but that is one thing that we are all interested in!

Louis
03-07-2017, 02:46 PM
:)
Well done!

orionn2o
03-07-2017, 05:27 PM
Not yet, but that is one thing that we are all interested in!

if he works that bit out, i might just buy another vr4 just to play! I'm sure i'll have broken it in weeks...

Confused
03-07-2017, 11:10 PM
Have modified a couple of entries in the VR4_AT_Base_PFL.xml file to correct ECUID and Case Part Number lookup... and maybe the MUT table too (although the MUT table looks better than it did, it may still not be correct!)

77953

foxdie
10-07-2017, 12:02 PM
Hi folks, here's a small update;

The gearbox mods have been trialled by fire at Santa Pod at the weekend and have also clocked up around 300 miles so far.

The best bit is the times. In 26'C ambient temps I clocked a 13.8 second pass, whereas a similar specced auto VR-4 without the gearbox mods clocked a 14.2 second pass (so nearly half a second quicker!).

We're still under the belief there's a lot more progress to be made but we'll keep updating this as more emerges :)

Louis
10-07-2017, 02:12 PM
Remember "Wave Spring", issues when you are tweeking!

Might be better testing ECU mods on a car that has had the wave spring replaced!


https://www.clubvr4.com/forum/showthread.php?46535-Auto-box-Servicing-it-and-wave-spring&highlight=wave+spring

Confused
21-09-2017, 08:37 PM
https://www.youtube.com/watch?v=2RbGoTaY3Y0

adaxo
21-09-2017, 10:53 PM
https://www.youtube.com/watch?v=2RbGoTaY3Y0

This is great, it was so annoying when you crawl to near stop an box drop to 1st, how to flash box with that mod?

Davezj
22-09-2017, 01:23 PM
i can do it you need mmcFlash dongle.

Confused
22-09-2017, 02:04 PM
It's still very early days, I'm sure there's more tweaking needed to make this change better then the drop into 1st - this is a couple of guys theorising and applying some basic tweaks to some tables we think define something, compared to Mitsubishi's engineers working dedicated on this!

But, currently, myself, Davezj and foxdie have the equipment and current knowledge to apply these changes - but we are still working on it, and still have lots of testing until we've got something we'll be confident in applying to other people's cars.

The key thing is that we've managed to do something we don't think anyone else has managed yet, which is to change the 3-1 downshift behaviour, which proves it is possible, but we might try find out good reasons why it was done this way, and why changing it might not be a good idea.

foxdie
22-09-2017, 03:09 PM
Yeah there's a LOT of work left to be done - I was up until 1am last night reverse engineering the ROM with a hex editor and found at least 20 undocumented tables in the PFL TCU ROM that need analysing and publishing.

Today I've been fiddling with the shift points, trying to get the car to get up into a higher gear earlier, got mine shifting up to 4th gear around 20 MPH and 5th gear around 30 MPH.. (my speedo reads 10% high..)


https://www.youtube.com/watch?v=ADUNDDVlaU0

TAR
23-09-2017, 07:09 PM
Some great work going on here guys. Well done. :happy:

Grid
06-10-2017, 09:09 AM
The key thing is that we've managed to do something we don't think anyone else has managed yet, which is to change the 3-1 downshift behaviour, which proves it is possible, but we might try find out good reasons why it was done this way, and why changing it might not be a good idea.

Really cool that you managed to make a tweak like that. As for the stock downshifts when decelerating - I am guessing it is done this way because the autobox ECU is minimising wear by not picking gears unnecesarily. Easy to imagine that this simple strategy saves hundreds of gear shifts during a day of city driving. Another possible reason - read somewhere that it is unwise to engine brake using an autobox (risk of overheating something due to the box reverse-driving the engine). The default strategy seems to indeed avoid engine braking by staying at a high gear until car comes to a stop.

Nick Mann
06-10-2017, 06:34 PM
The VR4 drops a gear going down hills if the car is gaining speed with no throttle input. So engine braking can't be so bad?

Amonlym
06-10-2017, 07:08 PM
Something i noticed is that when moving very slow, in third (heavy traffic on M3 northbound) the gearbox seems to detect a need for engine braking in the same way as the more common 5-4 shift.

Rolling at about 15 mph, slight downhill, slowly gaining speed. just about to reach for brakes and the revs jumped from ~800 to 1600, speed dropped fast, then revs dropped suddenly from about 1200 - 800 after speed was down to say 10 mph. Im guessing it enabled TC lockup? that or it was in 4th and i was mistaken (seems unlikely, had been 0 throttle from a standstill for a while). Perhaps this is a part of the 3-1 strategy and when it detects heavy braking (or downhill) it will make much more of 3rd gear braking than normally seen in an auto?

Grid
07-10-2017, 07:48 AM
The VR4 drops a gear going down hills if the car is gaining speed with no throttle input. So engine braking can't be so bad?

Thanks. Never encountered that, interesting... Can't find the source of where I read that bit about engine braking.

Come to think of it - the autobox is a fluid and a mechanical coupling. So as long as the oil pump is running and clutch packs inside gearbox are fully engaged, there should be no ill effects.

I still stand by my comment about avoiding unnecessary gear shifts being the default strategy. This is also very annoying on trackdays.

Davezj
07-10-2017, 06:37 PM
When traveling very slowly in 3rd gear.
If you get on the throttle at all the gear box may well try to change down to 1st before moving off. But sometimes the gearbox will try and change down to 1st and then about the change and go back to 3rd.

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