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I have decided to get rid of the Bosch ECU. The AFM is antiquated as it is, and the Motronic is a generic system that might have been great in 1988, but it is time to move the engine management of my S38B35 into current technology. Power and fuel economy improvements can be had with a new ECU system.

I am going with a wideband standalone, probably a Autronic SM2 or MoTeC M800. With both systems, I will use MAP, UEGO CO2, CDI, separate coils, etc blah blah, its just whether I want to spend $$$ motec or go the Autronic route. Im probably going to start on this late Feb and hopefully be completely finished by mid march.


I need to do this as my C230 is my current daily driver and puts the M5 to shame with 38mpg on the highway. This will give me an excuse to drive the M5 more.
 

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Autronic is both much better and cheaper. also MoteC compatible (dashlogger)
not so strange because its former Motec people that started Autronic.
 

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That sounds like a super idea. How much do you anticpate this will cost ? Can you do it all yourself with out a garage and how much improved do you expect the MPG will be?
 

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Jehu said:
That sounds like a super idea. How much do you anticpate this will cost ? Can you do it all yourself with out a garage and how much improved do you expect the MPG will be?

I have decided to go with the Autronic system. The MoTeC system, while the creme de la creme...the Autronic system can match it. http://www.autronic.com


Its not inexpensive, but I feel that since I will not sell this car, the benefits gained from the improved ECU outweigh the costs of the ECU. The system will provide a greater range of safety for the engine that the Bosch Motronic does not have. The system that I have decided to use:

SM2 w/ Autotune - $2100
Direct Fire CDI - $900
*UEGO exhaust analyzer - $1800
*UEGO Sensor - $1200
3X2 Double Coils - $240
Reluctor interface RPM pickup - $109

Thats what I have quoted so far. One BIG issue is the UEGO sensor. If I go with the Bosch LSM-11 sensor, it cuts the cost greatly. The LSM-11 sensor is $260 and the LSM-11 exhaust analyzer is $1300. The UEGO sensor is tremendously accurate, but the LSM-11 sensor is cheaper and will do the job. If I had the engine built for all out performance, then I would go UEGO no question.

I do not know the exact MPG gains. The Motronic system is just too primitive anymore. The precision and adaptability that is built into the current stand-alone systems will definetly make a difference. I have an email in that asks about what sort of economy will be gained.

There is more that I have missed.
 

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One HUGE factor that you mentioned Jehu, is whether this can be done by a person with minimal experience with EFI systems or if you have experience with EFI, can you do it yourself?

Autronic has this covered. The SM2 ECU comes with a feature called "Autotune." The SMC, a lesser ECU model, also has this feature. What Autotune does is this:


" The Autotune ™ will tune the engine with no input from the operator. The closed loop air fuel ratio table is used as the target air fuel ratio table for the Autotune software. This table is setup with the required air fuel ratios at various RPM and Load points.

An Autronic exhaust gas analyzer or any other analyzer that provides a 0 to 1 volt corrected output, is connected to the ECU O2 I/P, this is used as the actual air fuel ratio input. As the engine is run through its various RPM and Load points the software will adjust the volumetric efficiency numbers in the main fuel table to achieve the target air fuel ratio.

At no time do you need to touch the keyboard on the Laptop.

After the tuning is complete the analyzer and 02 sensor is longer need. At any time after tuning is finished the values in the target closed loop table can be changed, and the engine will automatically run the new air fuel ratio, providing you do not make a change to the volumetric efficiency of the engine, e.g. fit a different camshaft, modify cylinder head etc...

If the engine is modified so the volumetric efficiency changes, then the analyzer and Autotune ™ software will be required again to re-tune the engine.

The Autotune ™ software is much faster then a good operator. It is not possible to manually tune as quick as the Autotune ™. A typical engine will take less than 20 minutes to fully map on an engine dyno.

The accuracy of the Autotune ™ can be setup in the software from 0.5% to 5.0% accuracy. The default value is 2% accuracy, this is generally a lot more accuracy then most tuners manual tune engines."

"Overview
Autronic Autotune ™ software provides rapid hands-tree tuning of Engine Air/Fuel mixtures. This automated operation frees the engine tuner, allowing total concentration on safe engine/dyno operation. On road tuning of motor vehicles is even possible.

This software uses a complex combination of math, including statistics, trigonometry and fuzzy logic to intelligently adjust the fuel delivery tables. Initial tuning is rapid usually occurring within 1 second. High precision can be achieved by allowing the Autotune ™ to operate for an extended time at each engine operating point. The operator has control over the balance between tuning speed and accuracy. Accuracy is ultimately limited by the accuracy of the attached Air/Fuel ratio measurement equipment.

The program provides visual indication of the tune status. Automatic and manual storage of tune status allows the user to monitor the tuning progress even if undertaken in several sessions. Tuning usually proceeds 2 to 5 times faster than possible by manual means. Fuel savings of as much at 90% have been reported. The considerable savings in engine life are obvious.

This program also has elaborate diagnostics facilities and allows simultaneous operation of the ECU internal data logger and external P.C data logging.

Versions are now available that have live engine operating data graphs while tuning, and a live 3D graphical presentation of the tuning process."


Source:
http://www.autronic.com/page_files/autotune_feature.htm
I have a local shop with a dynamometer that is willing to let me go all day for a flat fee. They will even help and supply a UEGO sensor and UEGO exhaust gas analyzer. I will install the system onto my M5, make all the modifications I want, and then take it over there and let the system figure itself out. Of course, you have to initially tell the ECU what exactly you have it connected to and what you want it to do, but that is simple.

Of course, one benefit with this system is that if you make a modification, you can run Autotune, rather than have a chip made up for it. The bigger benefit is that you lose the AFM. You can also lose the plenum, which is an interesting idea. Maybe an S38B36/B38 plenum can be installed and the flap actuator programmed into the Autronic to open for intake runner length increase. Or just go with some snazzy intake trumpets or just run smooth rigid tubing from the stock plenum to the behind the grille with a cone filter.
 

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I have decided to get rid of the Bosch ECU. The AFM is antiquated as it is, and the Motronic is a generic system that might have been great in 1988, but it is time to move the engine management of my S38B35 into current technology. Power and fuel economy improvements can be had with a new ECU system.

I am going with a wideband standalone, probably a Autronic SM2 or MoTeC M800. With both systems, I will use MAP, UEGO CO2, CDI, separate coils, etc blah blah, its just whether I want to spend $$$ motec or go the Autronic route. Im probably going to start on this late Feb and hopefully be completely finished by mid march.


I need to do this as my C230 is my current daily driver and puts the M5 to shame with 38mpg on the highway. This will give me an excuse to drive the M5 more.
Hello
I want to upgrade my EMS too, I found the following one, and the information specify that you can use the original harness:

940864
 
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