TCU Tuning

[Chrs5topher]

Can anyone explain what TCU tuning is all about and why some say it's needed? I see the APR stage 1 doesn't have a TCU map, however speaking to a highly rated UK Audi tuning specialist, they recommend a TCU remap, so I'm a little confused at the benefits and when it becomes required.

I know a thing or two about old school ECU tuning, but transmission tuning has me beat. Does anyone want to give me the low down here? :)

My guess would be that it's a safety feature to not kill the transmission with too much torque?!

[wwhan]

Can anyone explain what TCU tuning is all about and why some say it's needed? I see the APR stage 1 doesn't have a TCU map, however speaking to a highly rated UK Audi tuning specialist, they recommend a TCU remap, so I'm a little confused at the benefits and when it becomes required.

I know a thing or two about old school ECU tuning, but transmission tuning has me beat. Does anyone want to give me the low down here? :)

My guess would be that it's a safety feature to not kill the transmission with too much torque?!

On a DSG TCU tune, one improvement would be to increase the dual clutch max hydraulic pressure (to handle higher torque loads). This is tricky to get the right amount of slip, to prevent jerkyness. Of course one can also adjust shift points (RPM, relative to throttle position).

ZF torque converter equipped automatic transmission, one can have increased holding pressure on the clutches and bands for the planetary gears. On torque converter equipped automatic transmissions one would also adjust the accumulator function which slows down & softens the clutch engagements (allows more slip & more overlap between clutches). One can increase the holding pressure and also minimize clutch slip to give a firmer shift. The lockup clutch can also be adjust for max pressure, proper slip and engagement MPH conditions.

It is possible to set up the torque converter equipped automatic transmission programming or valve body modification to allow the shifts to snap into place, but if made too firm and too quick, it may cause powertrain breakage or failure.

Here is a nice overview known as Jerry's Mod. Jerry Wroblewski (Ford Transmission Engineer). He designed the AOD/AODE transmission & article includes a lot engineering details & theory) of modifying a valve body torque converter equipped automatic transmission for better performance. I made these modifications, in 1999 on the AODE of my supercharged intercooled 99 Mustang. The transmission shifted very nicely snapped into gear smoothly and quickly: https://www.tccoa.com/threads/tech-a.../#post-2056310

If you have ever driven a 14' to 22' Uhaul Ford truck, you would notice how nicely (no slop) the transmission shifts, which is due to proper transmission programming.

[303 Spartan]

Can anyone explain what TCU tuning is all about and why some say it's needed? I see the APR stage 1 doesn't have a TCU map, however speaking to a highly rated UK Audi tuning specialist, they recommend a TCU remap, so I'm a little confused at the benefits and when it becomes required.

I know a thing or two about old school ECU tuning, but transmission tuning has me beat. Does anyone want to give me the low down here? :)

My guess would be that it's a safety feature to not kill the transmission with too much torque?!

In my experience, TCU tunes tend to be mostly about faster shifts, holding gears longer and increasing the rev limiter. At least, that's how it was with my previous cars.

When I tuned my old S4, I did the recommended TCU tune, as well. Many people love aftermarket TCU tunes to change how the transmission behaves. But some, like myself, actually preferred the OEM TCU tune and ended up flashing back to stock.

With my RS5, I couldn't imagine changing how the transmission performs. It shifts very fast, smoothly, and seems to shift at the perfect times. I also never loved the idea of increasing redline over factory settings. But that's definitely personal preference.

[wwhan]

The RS5 OEM transmission programming of shifts are quick and direct, without a lot of slop.

About the only thing I would change for the RS5 transmission is to have a switchable option with sport mode shifting into gear sooner and not holding the gear. This would need to be selectable, because track type driving (like with mountain roads and lots of corners) requires holding the gears, where as straight line driving does not, especially on the street.

[Chrs5topher]

Some great information there! Thanks people!

On the point of the second post, I also really like the shifting of the rs5 b9 transmission. I have my moments.. in drive I play let's get the best mpg ever whilst in sport I'm playing around so wouldn't mind a performance improvement.

Interesting about the RPM increase - I always worry that the higher you go, the more risk of parts that are moving faster can pop. I actually enjoy most of my driving on the low end torque and rarely hit the high RPMs. I'm also one of those freaks who really likes to use the manual option to shift when I want.

[Dan99]

Can anyone explain what TCU tuning is all about and why some say it's needed? I see the APR stage 1 doesn't have a TCU map, however speaking to a highly rated UK Audi tuning specialist, they recommend a TCU remap, so I'm a little confused at the benefits and when it becomes required.

I know a thing or two about old school ECU tuning, but transmission tuning has me beat. Does anyone want to give me the low down here? :)

My guess would be that it's a safety feature to not kill the transmission with too much torque?!

My experience is different than some of the other posts.

I had a B8.5 S4 with APR Stage 2 and the TCU. Previously I had a B8 S4. Both had the DSG transmission. The stock behavior on the B8 was horrible, especially as you were slowing down and coming to a stop. At times it would downshift and jump forward just as you thought you were stopping. The stock B8.5 transmission eliminated this problem and was better all-around in various driving modes.

When I installed the APR ECU I also did the TCU. My primary goal was that the TCU raised the shift point to take full advantage of the power band provided by the ECU. At first I did not like the behavior of the TCU, so I switched it back. After a while I did not like that I was not getting all of the power possible with the ECU, so I reactivated the TCU and drove extensively. Eventually I switched it back to stock just to test and decided I liked the TCU better. In addition to the higher power band, its shifts were remarkable. They did not bang in, they just shifted quickly and smoothly. You did not notice a gap in acceleration - it just pulled hard through all of the gears with seemless shifting. If you weren't paying attention you might not notice the shift under full power. It made the driving experience more refined and, if it shifted in the middle of a corner, it was not a hard shift and did not affect the car at all. It also made internal changes to the transmission so that it was more reliable with the increased power of the ECU. In my view, it was great.

In contrast, the ZF transmission in my RS5 SB is crude and I would swap it out in a moment if it was possible. It shifts at unexpected times and may do so with a bang. For example, it will occasionally bang a 1-2 shift while making a turn from a stop with minimal acceleration. More often than not the 1-2 shift is OK but occasionally it catches me and everyone else in the car by surprise, and not in a good way. I was hoping APR would do a TCU tune for the ZF transmission to tame some of its errant behavior.

So, depending on which car you have, a TCU may or may not be available. If you have a B8.5, I highly recommend it. I suspect it will be as good on a B8, but have no direct experience with it.

[303 Spartan]

Interesting about the RPM increase - I always worry that the higher you go, the more risk of parts that are moving faster can pop. I actually enjoy most of my driving on the low end torque and rarely hit the high RPMs. I'm also one of those freaks who really likes to use the manual option to shift when I want.

That was always a big concern for me, as well. Personally, I'm extremely uncomfortable increasing the rev limiter beyond factory specs. So much so, that when I did have the EPL TCU tune flashed, I found myself constantly switching to manual, simply so I could short shift it and stay below the OEM red line.

It's funny though... I'm terrified to raise the rev limiter but I'm perfectly comfortable tuning the ECU for significantly more HP/TQ than OEM spec. Go figure...

[wwhan]

I had a TCU tune on my B8 S4 Stage 2 & C7.5 S6 stage 1 to complement the ECU. The main reason is to make sure there was enough pressure to the clutches, to prevent excess slipping under the extra torque. I was never a fan of increasing the RPM of the shift points.

The RS5 shifts perfectly for me, except that I would like to have a straight line Auto mode where it would shift like Sport mode, but would not hold the gear & it would shift much sooner. I prefer the torque converter ZF transmission over the double clutch DSG. The ZF shift transitions are quick enough, when it decides to shift. It also feels smoother than the DSG.