Questions related to the ECU and ICU. I am fighting a sometimes stalling when hot condition. Some have suggested it could be the ignition control unit/module with part # 191 905 351B. The problem I have, I can not find that ICU anywhere in my 91 100. Every online catalog I have checked say this is the ICU I need.
On the right kick panel is the regular fuel injection ECU, under the left kick panel is what Bentley calls the knock sensor ignition control unit..it is # 443 907 397M.

control unit # 191 905 351B, which my car is supposed to have, is a 7 pin module. The only ICU I can find, # 443 907 397M is a 25 pin module.
I also have an identical 91 100 parts car and it has the same setup as described above.
Am I overlooking that 7 pin ICU somewhere, or do I have two of the rarest 91 100's in the world!
The Audi ETKA shows that unit being above and forward of the left side kick panel............but then ETKA also shows the unit I do have being on the right side...it is on the left. So certainly ETKA is not always accurate

thanks for any info and/or ideas

Thanks for the reply. Yes, I am familiar with the 25 pin ICU and the 35 pin ECU. After searching all over for the elusive 7 pin module, I had about decided my 91 doesn't have such a module. The reason I wanted to ask around....when I go to online parts store, including Arizona Autohaus where I buy a good amount of parts.... they all show my car having the 7 pin module.
I do know about the 3 pin power stage that is mounted next to the coil
Stalling is related to outside ambient temperature. The magic point when it will probably stall.........first it needs to be 98-100 degrees ambient or warmer. It then needs a drive of 45-50 minutes on the highway at speed. So far so good........but when doing stop and go driving, like waiting at red traffic lights...or maybe making a stop at a store and then continuing on. After maybe 30 minutes of that city type driving it happens. I get a couple very light surges...too light to call a jerk. The passenger likely won't feel it. When that happens i start looking for a spot to pull off the road/street. When I get those two (so far has always been two) surges, the tach does not drop...it continues reading normally, until the engine shuts completely off and the red warning lights come on.
Now that the weather has started to cool down some in Arizona, I probably won't have the stalling problem. I have never experienced the problem at 90 degrees ambient or cooler. Even if I do nothing, now that it is cooler, it probably won't stall until next June!
When the car does stall and quit...I sit and wait for 15 minutes..it starts right up. Sometimes it will take maybe three stalls and restarting before I get the 50 miles back home (freeway driving) other times, after sitting for 15 minutes, I can make the 50 mile freeway drive with no problems. If I wait 5 minutes, it will start up but will likely stall again within 15-20 blocks.

New fuel pump, new fuel pump relay..........have swapped both the ECU and ICU with another (used) unit. Have also swapped used ignition distributor, coil and power stage. I have an identical 91 100 parts car. Again, all the ignition parts I swapped were used, but with both sets, it has stalled exactly the same way

thanks again

John

It is indeed a test of patience trying to chase down the stalling problem. During the summer with ambient temps near or over 100 everyday, I was surprised if the car didn't stall. Now that temps have cooled a bit, I will be surprised if it does stall. Seems to not be a summer time car, at least summer in Arizona!
The speedo works fine...it has never not worked, and when the stall does happen, the speedo has never wavered a bit leading up to the stall.
I'm going to install a fuel pressure gauge.......I am not talking about the fuel pressure test equipment (which I do have) but rather going to hook up a fuel pressure gauge that I can watch when a stall does happen. Doing that may or may not indicate anything.....considering that the ignition is tied into the fuel pump relay, so even tho the problem might be ignition, it could also shut down the fuel pump.......which would indicate no fuel pressure...even tho the primary problem might have been something in the ignition shutting down first, and in turn, shutting down the fuel.
Why can't these cars be as reliable as a Toyota! When the Audi is running good, there is nothing I would rather be driving.....but when they act up.......oh my!!

I do appreciate your input