Also, any further progress on read/write to the TCU via OBD?

thx

Hi, Is Daz  DDillenger?  Sorry to hear of his passing. I had no idea. I have only been reading these boards for a few weeks but have come to realize he was one of the brightest stars on this site. I have been sending him some emails until my registration came thru but no reply. Now I know.

Wow! Okay so guys like us can take up the challenge to continue his work. I know he was well on the way to getting it working. I have been working in the electronics industry my whole life but don't have the in depth knowledge of software that he had.

Let's keep at it. It's surely worth the effort. I love my S4 otherwise.

Cheers

Well, adding on to our house this year. Hardware hacking the TCU is about all the time I will have to spend on the car.

I made up a rudimentary drawing of my understanding of the TCU circuits we are working on. I am going to modify it to show a way to make it variable, if need be.

I have a fair understanding of the TIP xmission but need to know how the line pressure affects the TC lockup pressure being applied. Does the EDS1 line pressure constantly keep a charge on the TC clutch circuit, ie, always applying X amount of PSI depending on the EDS1 condition, and EDS4 uses that pressure to control lockup, and when the TC seal goes bad it leaks past? If so, we should be able to help the marginal TC trannies' seals, hard, but not torn or otherwise buggared, by forcing EDS1 to make a bit more pressure. As long as having more line pressure doesn't negatively affect any other functions in the transmission. That combined with an earlier application of EDS4's regulating function, by lowering the resistance in series with it, or shunting a parallel  R on the TCU side of the coil, hopefully would allow us to get more miles out of our TIPs before total rebuild is required. Is there any way to measure line pressure on these babies?

I would rather work on the electronics side of it, rather than modifying spool valves and such. All this hacking can be done under the carpet, without even getting dirty. 

Lots to think about.

More coming.

Cheers

AARDQ, do you know for sure that the TCU is regulating the coils by watching voltage on them, or could it be monitoring current thru them? It's PWM I think, correct, just pulsing on/off to control average coil current? The reason I ask is that even if we eliminate the 1R in series with EDS4, max current will only be .65-.8A, depending on actual R of the coil, which I have discovered changes with temp. When cold and TCC is locked, I see .744A, and after it's up to temp, VAG reports .728A.  While it is regulating I can see it vary from .35 - .7A, then finally holds at .74 or so at TCC lock. If it is controlling by monitoring voltage, I wonder if the TCU is using the 1R as a sense R and measuring the voltage across that? Thinking about it, that makes more sense than measuring the voltage to ground on the coil. If this is the case, it will change how I was thinking of modding this.

I'll think some more while waiting for your reply.

Cheers

BTW, have you changed the soft coding in your TCU via VAG-COM? My original code was 00002 and I changed it to 00032, which is "sport" tuning, 00002 is "old man with a hat on the package tray" mode. Made a decent improvement, as did re calibrating the ECU with the "gas pedal kick down switch" operation.

It's up to 0C here today so I may go out and pull up the carpet and find the TCU and start modding.

more later.

Okay good, glad you confirmed that. After I thought about it for a while, it made more sense to use it as a measuring shunt. Cool. Now I can continue to figure out a "variable" hardware tune scheme for it. 

Long ago, when I had an E4OD in a big Ford truck, I completely rebuilt it, trans spring kit etc. I also figured out how the solenoids were switching and modified the coils and diode switching used in the valve body, to allow the TCC to lock in 2, 3, and OD, not just OD. Made a HUGE difference when pulling a 5th wheel. Also put a switch on the dash so I could lock the TCC whenever I wanted. That was a cool tranny after it was done.

Now I may wait until it warms up a bit. I don't want to trash my carpet, interior is pretty mint.

Thanks for the help. I see an old post now, you have put in a 6 spd manual. Appreciate the help.

Cheers

I know it was 4 years ago, but do you remember what values of R you played with for EDS1 and EDS4? Did you find it to be a linear function? I know you ended up at 1.1 and .8, but how high/low did you go and do you recall the results?  As mentioned, I may put a rotary switch in, or even just a DPDT switch so that I could have 2 or 3 different firmness settings, put it somewhere on the console.  I'm assuming these are SMT Rs, but looks like there may be room for thru hole types. Probably 2W should be fine.

Thanks again!!