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-   -   MK20 ABS unit differences (http://www.m3forum.net/m3forum/showthread.php?t=600006)

M3 dude Wed, Jul-11-2018 03:20:40 AM

MK20 ABS unit differences
 
Hello all,

my m3 is a 08/2001 and has the MK20 ABS module.
when i fitted a purple tag (same as yellow tag in LHD) rack, my ESC goes nuts during a spirited drive. ESC off is fine, but driving in varying conditions like that gets hairy.

I know the MK60 unit can be coded etc etc, but i notice some Mk20 owners dont experience the same ESC issues that I do. their cars are 2002 pre September (changeover to MK60).

MY questions are:
1. Are there variations in flashed programs between MK20 units (part #'s appear the same)
2. can the DSC module be recoded?

otherwise I'd have to rip out the rack and go back to STD.

thanks,

M spec Wed, Jul-11-2018 03:22:46 AM

Re: MK20 ABS unit differences
 
Check out BuildJournals recent MK20 tune. Helps, but alas to truly drive these cars you need to have DSC fully off. Unfortunately, not every e46 M3 is going to be safe with DSC off, so make sure before hand that your suspension and tires are in proper working order.

https://thebuildjournal.com/news/new...3-b-spec-tune/

Quote:

Buildjournal’s Sport DSC Tune will adjust your MK20 DSC parameters and ignition cut off so it is less invasive during spirited driving similar to M-Track Mode on the newer E46 M3s. Cars produced between 2003.5-2006 have the MK60 DSC unit which allows for M-Track mode, while older E46 M3 with MY of 2001-2003 are stuck with the older MK20 DSC unit. This MK20 unit doesn’t allow for M-Track mode to be enabled. As a result, we have figured out a way to mimic M-Track mode on the MK20 units that we will call Sport DSC Tune. This tune will significantly reduce DSC interference, but still keep it on in case of absolute emergencies. Keep in mind that driver experience will vary depending on different tire setups which is why we are releasing this as BETA.

M3 dude Wed, Jul-11-2018 03:47:39 AM

Re: MK20 ABS unit differences
 
thanks.
i've contacted them already, but they're not confident that their flash would fix my specific issue.

M spec Wed, Jul-11-2018 03:59:58 AM

MK20 ABS unit differences
 
When you modify the early model year M3ís, theyíre always going to get worse with the MK20. The software will lessen it, but again the 01-03 MY are going to be the more raw BMW experience requiring the DSC to be turned off.

Again, just make sure youíre using the correct tires and a refreshed and acceptable suspension

Volke Wed, Jul-11-2018 03:25:57 PM

Re: MK20 ABS unit differences
 
There's nothing you can really do on the MK20 currently. The issue is that DSC uses the position and rotation speed readings from the steering column rotation sensor to calculate the angle of the front wheels based on a known steering ratio. It compares this information against the readings from the yaw sensor to determine if the car is in control or not. When you change to a faster rack, the wheel angle is greater than the DSC unit expects it to be, and the car experiences greater lateral acceleration than expected, so DSC kicks in.

On the MK60, you can change to the ZCP steering setting (14.5:1) or use NCS Expert/Dummy to fake a 12.8:1 setting. This minimizes the interference, but DSC will never work as intended with a 13.7:1 rack until someone finds a way to either flash the DSC unit and change the steering ratio, or scale up the output of the column sensor to trick the DSC unit by either modifying the column sensor directly or intercepting the CAN signal with a dual CAN.

Someone on this forum is working on a dual CAN, but it will be a while before it's ready.

bimmerfan08 Wed, Jul-11-2018 04:55:35 PM

Re: MK20 ABS unit differences
 
Quote:

Originally Posted by M spec (Post 1067843237)
Check out BuildJournals recent MK20 tune. Helps, but alas to truly drive these cars you need to have DSC fully off. Unfortunately, not every e46 M3 is going to be safe with DSC off, so make sure before hand that your suspension and tires are in proper working order.

https://thebuildjournal.com/news/new...3-b-spec-tune/

Have your or anyone else here tried this new tune/reflash for MK20? Seems intriguing.

M spec Wed, Jul-11-2018 06:14:06 PM

Re: MK20 ABS unit differences
 
Quote:

Originally Posted by bimmerfan08 (Post 1067843396)
Have your or anyone else here tried this new tune/reflash for MK20? Seems intriguing.



Not yet, however I did talk to Oscar and Connie who were testing it. Oscar is very upfront about it not being a perfect solution, but it does help.

Once the body shop is finished with some work Iíll be having Oscar tune/code my car. Iíll try it and report back, as the DINAN setup (JRZ/Champion) makes the 02 undriveable with DSC on, which isnít normally a concern for me, but if something is available, I want to try it.

mercedesc63 Wed, Jul-11-2018 10:25:05 PM

Re: MK20 ABS unit differences
 
When I had my 02 E46 M3 I wanted to upgrade the steering rack.. i learned a few things first of all that purple tag zhp rack is linear whereas the e46 m3 comes stock with a progressive. In addition according to my research the zcp rack works fine on a MK20 which is a slightly faster rack 15;4 vs 14:5 both progressive. Also I reccomend that new dsc tune and i really do think it can settle the dsc down a lot in theory.

I discovered the cheapest and easiest way to run a purple label rack is by getting a racelogic TC (discontinued) wiring it in and fine tuning it. This system works off of the abs and detects slip and cuts power to regain traction. Whereas the dsc systems like mk20 or mk60 run a lot off of steering angle/speed of steering which is why these systems never really agree.

Bottom line the MK20 doesnt have some of the sensors or capabilities to adapt to a change like a steering rack swap especially a linear one. Swapping racks never really does work 100% even on a mk60 because lets face it you are messing with something that was engineered a certain way for a certain reason.

M3 dude Wed, Jul-11-2018 10:35:31 PM

Re: MK20 ABS unit differences
 
yeah thats gonna do my head in.

looks like i gotta find time to swap racks again.

the car is set up wonderfully neutral, on the track and dry roads i run dsc off no problems.

what bothers me is doing all that in the wet / or varying grip conditions

M spec Thu, Jul-12-2018 05:19:31 AM

Re: MK20 ABS unit differences
 
Quote:

Originally Posted by M3 dude (Post 1067843492)
yeah thats gonna do my head in.



looks like i gotta find time to swap racks again.



the car is set up wonderfully neutral, on the track and dry roads i run dsc off no problems.



what bothers me is doing all that in the wet / or varying grip conditions



For the price the BuildJournal tune is a phenomenal deal. Certainly wouldnít hurt to try it out before swapping back.


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