Disabling O2 sensors completely DIY

[ogorek]

First of all i take no responsibility, work at Your own risk.

Some people may know, there have been few E31 without catalyst, and becouse of that without O2 sensors. Below, eprom image from such car. To make it work You need to have catalyst removed, o2 sensors disconnected and MAF's with screw installed.

You need also to visit exhaust analyser and regulate CO using this manual

http://www.bmwtechinfo.com/repair/ma...et1/721186.jpg

To burn the image You need to have 27c256 EPROM's.
Bin:
http://www.multiupload.nl/MULKRRTX9F

I can also burn and send such an image if costs returned.
Also, i have no-o2 version of wokke chips but to send it, i need to have permission from wokke, becouse this is his property. So you need to buy his chips first.

Have fun.

P.S there is a manual how to reprogramm Your existing chip with MODIC, but this procedure doesnt work for me. This is the solution that worked for me.

[Omega man 1969]

Thanks for posting this info. I will take a look at that file to see what changes were made.

There is no reason not to have O2 sensors without Cats though, I have O2 sensors with the cats removed. I can see in certain situations it would be nice to set the Air/fuel at a fixed value but it would take some time to setup properly.

So is there a bit in the code somewhere that tunrs off Lambda correction?

[ogorek]

You dont need o2 sensors if no cats. This is why BMW used this that way. For me its always problems with failing o2 sensors, adaptation values etc. Its only ecology. The car runs smooth right now as never before without o2 adaptation. Why would i need catalyst protection, if i dont have catalysts

Its the first symbol of variant code that determines if its a o2 sensor control car or not.

[Omega man 1969]

Yes but at part throttle the car can constantly adjust fuel to keep it running more efficiently depending on fuel grade/ air temperature etc......Surely lambda correction would be more effiecient than set tables.

Saying that, I like having the choice between Lambda correction or not for tuning.

Right I see, thanks for the picture, so at what address is the variant code located in the bin file?

[ogorek]

I dont know becouse i dont have original version of this bin with o2 control. I have few bin's but non of them contain this software version - and they are different.

[Omega man 1969]

The bin file is software number 1736635 from a 0261200352 Motronic. E32 750. E31 850

Maybe worth searching for the original HEX string in the standard bin file for a 750 e32.

I can guess most of the options but have no idea what "free postion" or "stadard Variant" would refer to.

[ogorek]

f052

[Omega man 1969]

Bingo!!! location 1E56

On the standard file it is C052 = 1100000001010010 So switching the 3rd bit to 1.....1110000001010010 would disable O2 sensors on an 850.....cool!!

Thanks for that

Its located at the same address on the CSi, its very close to the software and DME number. Mine is 8052 which is also written on the silver DME case sticker, just below the chassis number. very interesting.



So it looks like you can also tell the DME to not look for the EML and use cables throttles.

[ogorek]

Thanks for that my friend. Too simple for me to figure it out first

Oh one more thing, the checksum will change. Open the file with HxD lookup the checksum with checksum-16 (4 digits) and You need to have the same checksum when You finish editing the file. Otherwise You will get DME control unit errors in ECU. I do it like that:
1) look up FFFFFFFFFF on the end of the file (unused)
2) insert 000's or other symbols to make checksum match

There is checksum in the file somewhere written... dont know where, didnt find it

Yes, and You can switch to manual also

[Omega man 1969]

No problem

I dont seem to have that on mine, I have written over the standard data and have no warning lamp....I even wrote the file from 1 DME to both...the only difference I could find in the files was the number 372.09 located at 1E20... that number is also on the case on the white sticker above the silver one.


Do you know where the start and end address of the checksum calculation or does it use the whole file?

[ogorek]

I guess the whole file becouse i do changes in the ending FFFF's and it affects. Writing 1 dme to both is no problem i do that all the time. I dont think You dont have checksum. Maybe it didnt change for You. When i moved wokke maps from his chips red lamp came up. Dont know if its the same in CSI but in regular 850 You dont have the red warning lamp bulb in instrument cluster by default. Maybe You have error in DME and You dont know.

[Omega man 1969]

The light is there so maybe like you said...tunerpro could be updating the checksum automatically, I look at it. If not then it would be easy enough to work out if it is the whole file range. But.....if it was then the different part numbers between the 2 DME's would make a change to the calculated checksum and there would be a checksum value stored........the files are identical apart from that number so unless that number is the checksum then It can't have one.

Or it is within a certain range within the code and is the same value for both DME's.

It so hard to find info on these DME's....the Pro's keep it well hidden from prying eyes

[ogorek]

If the german engineers would see what we are doing they would turn in one's grave Tunerpro didnt calculate checksum for me

[Omega man 1969]

HA Ha yes!

So when you calculate your checksum before you make changes what address do you start and end at? 0000-7FFF ?

I will try this O2 sensor disable out on my car this afternoon.....just to see what happens to my wideband logs at part throttle. I wonder if selecting different fuel ratings makes the DME select different timing maps? I wonder what the KD(sERVICE-ECE ONLY) does?

[smokum]

!!! Keep up the good work

[Omega man 1969]

Add this to your XDF


1 MINUTE, I need to make some changes to that....I will paste it back in a minute.

<XDFFLAG uniqueid="0xB69">
<title>Unleaded or Leaded fuel option set for unleaded</title>
<description>0 for Leaded 1 for Unleaded</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x8000</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x730A">
<title>Super or regular fuel, set for Regular</title>
<description>0=super 1=regular</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x4000</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x5AAF">
<title>O2 sensor on or off. Set for off.</title>
<description>OFF=1 ON=0</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x2000</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x48A">
<title>BIT 1 OF 3 COUNTRY CODE, OFF ONLY. EXPERIMENTAL</title>
<description>ECE,US,JP,TROPICS AND KD SERVICE ECE ONLY. ACTUALLY A GROUP OF 3 BITS SO YOU NEED TO CHANGE 3 FLAGS.</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x1000</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x6724">
<title>BIT 2 OF 3 COUNTRY CODE, SET FOR KD SERVICE ONLY (ECE)</title>
<description>SET THIS TO ENABLE KD SERVICE (ECE ONLY) NOT SURE WHAT THIS IS</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x800</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x3A52">
<title>BIT 3 OF 3 COUNTRY CODE, SET FOR TROPIC.</title>
<description>SET FOR TROPIC, OFF IS FOR ALL OTHER OPTIONS.</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x400</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x611">
<title>MANUAL, AUTO GEARBOX OR EGS GEARBOX</title>
<description>SET FOR EGS OR AUTOMATIC, OFF FOR MANUAL.</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x200</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x3A4C">
<title>MANUAL, AUTO GEARBOX OR EGS GEARBOX</title>
<description>SET FOR EGS ONLY, OFF FOR AUTO OR MANUAL</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x100</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x7CCD">
<title>VEHICLE SELECTION BIT 1</title>
<description>OFF FOR ALL VEHICLES</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x80</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x6E1C">
<title>VEHICLE SELECTION BIT 2</title>
<description>SET FOR E31 ONLY, OFF FOR E36/E32/E33</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x40</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x4E00">
<title>VEHICLE SELECTION BIT 3</title>
<description>SET FOR E32/E33, OFF FOR E31/E36/E32</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x20</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x461A">
<title>FREE POSITION, UNKNOWN</title>
<description>EXPERIMENTAL</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x10</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x48AB">
<title>PURGE VALVE ON OR OFF</title>
<description>SET FOR NO PURGE VALVE</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x08</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x330">
<title>EML ON OR OFF, SET FOR NO EML</title>
<description>SET FOR NO EML</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x04</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x257D">
<title>ASC+T OR STANDARD</title>
<description>SET FOR STANDARD</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x02</mask>
</XDFFLAG>
<XDFFLAG uniqueid="0x7724">
<title>STANDARD OR VARIANT</title>
<description>EXPERIMENTAL. SET FOR VARIANT.</description>
<EMBEDDEDDATA mmedaddress="0x1E56" mmedelementsizebits="16" />
<mask>0x01</mask>
</XDFFLAG>

[Fatandre]

What will that do?

[Omega man 1969]

Just makes it easy to turn on or off the options when viewing the file with Tunerpro software.

[ogorek]

Nice tunerpro mod! Good job! I start editing from the last symbol of the file and go backwards. Checksum of finished file must match original one. I use HxD editor to count checksum-16 and modify

How are Your feelings on driving without o2 sersors in CSI?

[Omega man 1969]

Ok thanks.

I am about to switch my sensors off using the variant code. I have tried to enrich the part throttle mixture without success. Even at high load while the O2 sensors are still running its 14.7 to 15:1 .....If I can get that nearer 13.2 I can up the advance and squeeze some more power out

I'm going to make the low part throttle leaner for economy, it doesn't need to be as rich as it is currently.

I spent some time tunnig the car some more yesterday, it's really flying now.....the difference between the original file and my current one is night and day.

Ogorek, have you noticed the file you posted (eprom.bin) it is set for :
Unleaded
Regular fuel
O2 sensors off
and 1 for the first bit of the country code.....that option isnt listed on the Variant code picture you posted....a mistake ? or another option that isn't listed maybe.

[MADMAXER]

Could this be done on a CSI and what would the benefits be?

[Omega man 1969]

Yes it can, depending on what mixture you set part throttle areas at you may need to remove your Cats. You can set the mixture a fair way leaner and gain mpg at cruising speed or richen it up a little for more power. You'd need to adjust the ignition timing to suit the mixture.
Full throttle doesn't use oxygen sensor feedback so no change there.

I like to have the sensors enabled, that way if you develop problems ....air leaks, bad MAF etc you can see the fuel trims flag a problem in diagnostics and know you have trouble.

[BobieM]

I like to have the sensors enabled, that way if you develop problems ....air leaks, bad MAF etc you can see the fuel trims flag a problem in diagnostics and know you have trouble.

+1....I'll take all of the OBD hints that I can get.

[TIRAX]

Why can you choose between EGS or AUTO? Is it because there has been 5hp30 and 5hp24 boxes?

[Auraraptor]

I wish there was a way to flash to remove the rear Sensors on OB2 cars...