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      01-17-2017, 04:18 AM   #58
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Drives: 2011 135i M Sport
Join Date: Jun 2016
Location: Australia

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Warning long winded post.

So I think I have now got this sorted. I had a bit of a problem with the placebo effect as I would try something, restart the motor and move the wheel and think it is lighter. It is only when you turn to full lock do you feel the additional load that is required without Servotronic. In addition past 30 kph the additional weight is really not a factor.

To answer the post above they are basically the same rack. Same ratio, same fitment apart from the hydraulic pipes may be slightly differently oriented.

The issue has been whether you can get Servotronic operating on a 135i.

I have managed to get the speed adjustable assistance working in a more meaningful manner than the hit and miss that was previously the case. The weight is the same as without Servotronic in the quarter turn either side of straight ahead but the servo assistance kicks in past there and takes off the additional load as you add the additional three quarters turn. The reason for the additional weight is the amount of caster built into a 135i (approx 7 degrees stock) which means you are actually lifting the car as you are turning the wheel. It is accentuated with mine as I have 8.3 degrees.

The 135i pump is smaller than that on the M3 and 1M and I assume this means that the hydraulic pressure is less and so more human effort is required.

The new steering weight is not as light as a standard 135i and probably heavier than the sports mode on a M3 or 1M, but not un wieldy as with no Servotronic. This only really relates to parking speeds, other than that it is a little lighter up to 30 kph but faster than that feels the same as before the Servotronic function was active.

The next thing is to thank the author of NCS Dummy and the member who
posted a 1M FSW_PSW dump file on this forum. The dump file enabled me look at the difference between the instructions of a 135i and 1M and trace down the ecu other than JBBF which needed to be re coded. NCS Dummy helped find what was required in the Kombi ecu.

What came up was that the following instructions were active on a 1M and inactive on a 135i. I coded them in as active and this settled down the rather on/off Servotronic assistance I previously had. (I was aware that the Servotronic function was working after I had coded in the option as when I disconnected the wiring I would get a fault come up and there was a current running to the valve but it fluctuated wildly).

ST_MDRV_ALIVE_MONITOR
aktiv
ST_MDRV_CSUM_MONITOR
aktiv
ST_MDRV_ID_MONITOR
aktiv

So there you have it, add the option $216, recode the whole car, alter JBBF to Servotronic aktiv and make the changes to the kombi ecu as above.

It is not as assisted as a 1M but it is a lot better than none at all.

There are a host of ST_ and other instructions in the JBBF ecu which are steering related and they are the same between a 135i and a 1M. These may adjust the level of assistance but I am not sure I want to tamper to much with these. They may only relate to activ steering or electric steering. I am happy with the way it is.

I am not going to put in a big warning about doing this at your risk as I have found the ecus' to be remarkably resilient to cock ups. These are only minor changes and I also found that NCS Expert will not allow you to make alterations to instructions that are not reasonable.
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