V6 12V VAGCOM badness

[S2central.net]

Cheers Simon... does seem like the old girl would benefit from breathing mods and yes the cats have to go at some point...

I have dug up this link for how to extract blink codes without the blue plug - will try later.

http://20v.org/fault.htm

I also found this rather useful post on Audi World from someone that appears to be 'up' on the V6...

The MMS200 series was the first Engine Control Module (ECM) series for the 12v V6 engine. It was adapted from the MPI Engine Management System and included On Board Diagnostic I (OBD-I) capabilities. The ECM itself is made by Bosch and contains an 8-bit microprocessor with 48kB system memory.

MMS 300: With this version, the MPI ECM was completely rewritten. This ECU was the first to incorporate adaptive learning functions such as oxygen sensor control. The MMS300 ECM was used from October 1992 to early 1993 production in Audi 80/90 and 100 models. The ECM is made by Hitachi and contains a 16-bit microprocessor with 60kB system memory. The ECM has the same four connectors as the MMS200 series ECM, but the terminal functions are different and the control module is not backwards compatible.

Successor versions to the MMS300 ECU using OBD-I are designated MMS311. The MMS311 series ECM was used in all 12v V6 models from 1993 to 1996, when OBD-II was introduced.

MMS 400: With this version, On Board Diagnostic II (OBD-II) was introduced for the A6 with manual transmission and front wheel drive. OBD-II included the addition of a second pair of heated oxygen sensors after the catalytic converters and new OBD programming. To accomodate new features, an additional 32 input/output pins were added to the ECM. Successor versions to the MMS400 ECU are designated MMS411 and MMS411A. The MMS411 series ECM is used in 12v A6 and Cabriolet models from model year 1996 on; the MMS411A series ECM is used in 12v A4 models.

Guess I am just going to have to wait for the factory info to land here and meanwhile pour over AAH schematics thru the years. It would seem the MMS200 is the most easily chipped - being allegedly a Bosch ECU there is at least a chance that I can reverse engineer some sense out of it and locate the essential maps. I think it should respond nicely to more aggressive timing and bigger/less restrictive MAF someday - trying to remind myself this old V6Q aint a project car... The later Hitachi ECUs allegedly have microprocessor with built-in program memory, but they aren't programmable via OBD - AFAIK.

Seems like the early V6 ECUs are properly awkward (like early 7A) and have oddball OBD-1 capability - as opposed to OBD-2 which VAGCOM expects.

[V6quattro]

I have a Audi 80 2.8 quattro 92'. A long time a go i successfully read out the ECU whit a cheap ODB connector and VAGCOM software. It worked fine. But now my engine is running not so good so i try to read the ECU. I plugged in the ODB connector end try to connect the ECU. But it says ´Vagcom can not communicate whit the ECU.` I still downed know what it is. And i think it is very strange that it is not working anymorge.

The timing bled is a piece of cake. Specially if you have the special tools for the job.

[S2central.net]

mmmm - do you know if ECU was MMS200 or not ?

PS - hope to get your other ecu done tonight !

[V6quattro]

I don't know what kind of ECU it had. But it is one of the first 2.8 quattro's whit a manual airco. If you realy want to know it i can take out the ECU.

PS. I cant wait to get it back! I given my car a good service so it is good to go!

[S2central.net]

You cannot trust anything on the internet at face value... Curiousity got the better of me tonight - and I removed the ECU from the V6 - its all Hitachi - MMS200 with a separate EPROM - which I have also removed and fitted a socket in readiness for some 'fun' with an emulator one fine day.

[S2central.net]

Oh but it gets better - there is a Hitachi micro in the ECU - variant of the 6800 family - my favourite micro from days of old. Bring on the disassembler and another beer

[S2central.net]

You do have to love the internet sometimes though - click here for a photo of internals of the V6 MPI ECU I have - freaky or what - there's the rice influence though.

[S2central.net]

Its not a perfect match, but the commonality is significant... Amazing what a search for some cryptic chip numbers will turn up.

[S2central.net]

So here's the next bit of fun... the micro has 16k internal ROM and 32k external. Trouble is the reset vector is at top of internal ROM so at the moment I have no way to determine the entry point into the external chip - and so cannot start disassembly... Gonna have to build a one shot latch unless I get real-time trace support anytime soon.

So I'm going to calm this all down now - line it up for a winter project some other year and put this chip back in and close the box for the time being. No more projects - maybe its a red car disease.