Mercedes Benz CIS

Discuss Bosch (Porsche, BMW, Volvo, etc) tuning topics here. Request definitions, discuss parameters, etc.

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Duckmang
Posts: 3
Joined: Mon Jun 01, 2020 5:17 pm

Mercedes Benz CIS

Post by Duckmang »

I'm starting a thread about the Mercedes Benz 6 cylinder 55pin modules. Specifically for the 104 engine, but the 55 pin 103 module is very similar. The 119 V8 CIS module is almost identical in function, but its an entirely different beast on the circuit board and not addressed in this thread. The 6 cylinder 55 pin modules use the 27c256 EPROM, which is a chore to desolder. With a socket soldered in place I'm using the Ostrich emulator to tune on the fly and data trace.

The impetus to take on this module stems from my California version 104 module's poor performance on a moderately modified engine. Lacking any WOT enrichment I was determined to figure out how to tune these modules. After finding TunerPro and being disappointed with the XDF available on the site, I set out building my own. Thus far I have 19 defined tables and a couple of scalars.

Number 1 is the WOT table. It allows up to +15mA of EHA current in 500 RPM increments with the WOT switch closed. These modules also have an acceleration enrichment. Sudden increase in airflow potentiometer voltage results in a shot of +EHA current. The amount defined in a 2d table. This function turns off above 83C so I have defined the scalar that sets that temp. Using the scalar you can set the temp much higher than operating temp to prevent the function from being turned off.

My second goal was raising the idle speed. These engines tend to overheat in hot weather due to low idle speed not circulating enough coolant to keep temps in check. I've defined several idle tables with decent success at raising the idle speed but it isn't cut and dry and I'm still trying to sort out random idle limp mode.

My list of defined tables:
WOT enrichment
Accel enrichment
Warmup enrichment
Afterstart enrichment
Cranking enrichment CLT***
Cranking enrichment IAT***
Low load lambda
Lambda delay***
Idle lambda
Idle valve output
Idle park neutral CLT***
Idle drive reverse CLT***
Idle park neutral IAT***
Idle drive reverse IAT***
Idle park neutral a/c on
Idle drive reverse a/c on
16 bit airflow potentiometer transfer function
16 bit IAT sensor curve
16 bit CLT sensor curve

*** = pretty sure but not 100%

Defined scalars
accel enrichment cutoff temp
EEPROM clear start address

I still have over 30 tables defined that I don't know what they do. These modules don't have the convoluted addressing scheme some other Bosch modules have. They do have a section in the code pointing to most of the map addresses, so it was pretty easy to find them. Figuring out their function, not as easy.

If anybody is interested chime in. I'll happily share my XDF and BINs.
mahdi93
Posts: 32
Joined: Tue May 05, 2020 12:22 pm

Re: Mercedes Benz CIS

Post by mahdi93 »

im very interested bro
d.mahdi.121093@gmail.com
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