RS6 - torque convertor cicuit, stuck fault - advice needed

[agent5150]

Hi, I have a low mileage RS6. Check engine light came on and I took it to local Audi shop who service my RS6 (did timing belt replace etc). They said it was Torque converter circuit stuck error and told me they have cleared it but I will need to replace the torque converter soon. Car has 44K miles on it and I have kept up with all recommended/periodic/wear related maintenance. It is completely stock with no modifications.

I am in process of getting torque converter replacement cost estimates parts/labor (decided to use edge/ace torque converter), but here's the thing, I used torque pro app on my android phone and a bluetooh OBDII reader, it only found fault "C02E5 - Chassis" and no other fault.

My question is, could they have stored the torque converter fault as C02E5? if not then why am I not seeing the fault again? ie if I did have the dreaded fault code for torque converter stuck, can it be cleared permanently? if not, then why am I not seeing that fault either has stored fault in ECU or a a new instance of it after it was cleared?

Apologies if I sound like a noobie.. I am one with this car. Long time wish to own one, came true about 10 months ago. I had this car checked by dealer and they said all it needs is the timing belt as the previous owner didn't do it at 35K due to lack of use.

Appreciate any advice I can get on how to go about with this TC issue?

[canyon]

Drive it and see if the light comes on. The fault you'll get for the torque converter will be P0741 Torque Converter Clutch Stuck Off. If it doesn't come back then you're good to go......for now.

[agent5150]

Drive it and see if the light comes on. The fault you'll get for the torque converter will be P0741 Torque Converter Clutch Stuck Off. If it doesn't come back then you're good to go......for now.

Thank you. So can I safely assume that the stored fault "C02E5 - Chassis" is not related to torque converter.

[lswing]

You want Ross-tech.com to read all the codes correctly. Many torque converters have failed at lower mileage, many seemed to have a faulty seal. Danger of more driving can be the slipping of TC creating higher fluid temps and cooking the trans. I've tried the Torque and other OBD2 Bluetooth apps, very limited code info.

TC slippage test; Tip mode, 5th gear cruising at 50mph, give it gas but not enough to hit kickdown switch. You'll see RPMs rise ~500 or more before your tach moves if slipping.

[agent5150]

You want Ross-tech.com to read all the codes correctly. Many torque converters have failed at lower mileage, many seemed to have a faulty seal. Danger of more driving can be the slipping of TC creating higher fluid temps and cooking the trans. I've tried the Torque and other OBD2 Bluetooth apps, very limited code info.

TC slippage test; Tip mode, 5th gear cruising at 50mph, give it gas but not enough to hit kickdown switch. You'll see RPMs rise ~500 or more before your tach moves if slipping.

Thanks. This is why I was asking about the fault completely disappearing.

Need some help with the TC slippage test. Please correct me if I have not understood the process.
a) be in manual shifting mode.
b) 5th gear cruising at 50 mph
c) give gas but not let it downshift?
d) You'll see RPMs rise ~500 or more before your tach moves if slipping (not sure I understand seeing the RPM rise before the tach needle moves...do you mean I will feel or hear the rise of rpm before such rise is displayed by tach needle?

[DHall1]

Last 6 of vin?

[agent5150]

Last 6 of vin?

Here you go: 904645

[DHall1]

Depending on how early you catch the failure.....a TC can last 10k or 50k before the whole trans takes a crap.

Early vin...sorry about that

Is the trans shifting properly at all times? Even kick down on hwy

[agent5150]

yes transmission shifting normal in all modes. yes on the highway evwn kick down.
That is the reason i am not sure if the fault was true.

Early vin.. sorry in what sense? it has all the recalls taken care off. Anything in particular I need to worry about due to early vin.

[DHall1]

Yeah

You just experienced it. The TC

[agent5150]

Yeah

You just experienced it. The TC

Doh!:fastm:

[lswing]

Thanks. This is why I was asking about the fault completely disappearing.

Need some help with the TC slippage test. Please correct me if I have not understood the process.
a) be in manual shifting mode. YES
b) 5th gear cruising at 50 mph YES
c) give gas but not let it downshift? YES - 1/2 to 3/4 throttle, just not to the floor, don't hit the kickdown. The kickdown should never be hit really, it's a hard shift and can only do bad things to the trans.
d) You'll see RPMs rise ~500 or more before your tach moves if slipping (not sure I understand seeing the RPM rise before the tach needle moves...do you mean I will feel or hear the rise of rpm before such rise is displayed by tach needle?
YES - Basically your RPM's will increase before your speed does. I believe the TC should be in "lock" when cruising in 5th, so both RPM and speed should rise together, very close at least ~100 RPM. When my TC failed, and I did this test, the RPM's rose about 400-500 before my speed increased. This is the TC slipping before finally building up enough speed/energy to push the car forward.


I had the check engine light, although I thought it was P0745 stuck open, not P0741 Torque Converter Clutch Stuck Off.

[lswing]

Yeah

You just experienced it. The TC

Cold...:rolleyes:

[ddillenger]

Not that it's a fix or anything, but I can disable the torque converter lockup clutch entirely. This will prevent it from attempting to lockup, superheating your fluid, and killing the transmission. It will also prevent the fault code. It's not a fix, more a bandaid for someone that wants to continue driving the car without doing damage in the process.

[DHall1]

Yes that would help ^^

[agent5150]

Not that it's a fix or anything, but I can disable the torque converter lockup clutch entirely. This will prevent it from attempting to lockup, superheating your fluid, and killing the transmission. It will also prevent the fault code. It's not a fix, more a bandaid for someone that wants to continue driving the car without doing damage in the process.

How? please do share.

also, I did the slip test, did not see or feel rpms rise without speed with curising at 50MPH in manual mode 5 gear. stays put a 1/2- 1/3 gas paddle. drops to 4th if I let it slow down.

Will be visiting my local audi tech shop to have to check to fault code again.

[ddillenger]

How? please do share.



By flashing the tcu. It's nothing I can give instructions for I'm afraid, and it requires some specialized equipment.

[agent5150]

By flashing the tcu.

Hope my audi tech guy knows how that is done. I am assuming you are calling out a change to TCU programming.

If I do disable the TC lockup clutch, what will be change on up/down shifting and power?

[ddillenger]

Hope my audi tech guy knows how that is done. I am assuming you are calling out a change to TCU programming.

If I do disable the TC lockup clutch, what will be change on up/down shifting and power?

I can confidently say that I am one of two people in the US that can do this. Yes, it is a change in the tcu programming.

As for change in shifting, none. Power, none, however the tcc will never lock, so there is waste there.

[agent5150]

I can confidently say that I am one of two people in the US that can do this. Yes, it is a change in the tcu programming.

As for change in shifting, none. Power, none, however the tcc will never lock, so there is waste there.

Nice. Hacking programming to work around the weakness. What does it do to the transmission in the long run. Am I buying time to deal with the expensive replacement or are you saying one can pretty much run without the lock as long as the tranny works :)

[ddillenger]

Running without the lockup will generate a bit more heat. HOWEVER, it will generate substantially LESS heat then a slipping converter clutch, and none of the particulate from the clutches winds up in your oil. You can run without the converter clutch indefinitely.

[lswing]

I thought the TC only locked when in cruising gear, usually 5th, maybe 4th, to be more efficient fuel wise?

I know that it's open when stopped, and in regulating mode when accelerating. I was under the belief that this slipping TC would also cause heating during this period since it can't accurately transfer power and is spinning extra. You also get the max torque through the TC during this regulating mode causing more issues.

Please correct me as I'd like to be spot on with this.

Daz, you in NY, Dyno, tune my car this spring?

[ttboost]

When my TC went, I was getting a 17125 code.

[lswing]

How? please do share.

also, I did the slip test, did not see or feel rpms rise without speed with curising at 50MPH in manual mode 5 gear. stays put a 1/2- 1/3 gas paddle. drops to 4th if I let it slow down.

Will be visiting my local audi tech shop to have to check to fault code again.

Good to hear. Get Ross-Tech, easily worth the $250, you can check everything and clear random codes, like an EVAP that could pop up.

Anyhow, you accelerated without noticeable slip, good. Maybe the problem is just starting, not full blown,
maybe random sensor. Mine didn't fail until 85k, with the last 10k having a powerful tune upgrade.

[DHall1]

This would be 100% correct.


Running without the lockup will generate a bit more heat. HOWEVER, it will generate substantially LESS heat then a slipping converter clutch, and none of the particulate from the clutches winds up in your oil. You can run without the converter clutch indefinitely.

[ddillenger]

Anyhow, you accelerated without noticeable slip, good. Maybe the problem is just starting, not full blown,


This is the most dangerous condition. When it all out fails it's no longer slipping, and not nearly as dangerous as it is when it sorta works (generating excess heat and sediment)

[lswing]

This is the most dangerous condition. When it all out fails it's no longer slipping, and not nearly as dangerous as it is when it sorta works (generating excess heat and sediment)

If it failed/locked completely the car would barely drive I would think, or be very rough. It has to open up to stop. Also, it's just fins in the TC I thought, no clutch disc at all.

[lswing]

If it failed/locked completely the car would barely drive I would think, or be very rough. It has to open up to stop. Also, it's just fins in the TC I thought, no clutch disc at all.

Nevermind, I used the Google, noticed the clutch pack for lockup in the TC. Still, to drive decent it has to open and regulate, so I think the OP's isn't that bad off.

[ddillenger]

Nevermind, I used the Google, noticed the clutch pack for lockup in the TC. Still, to drive decent it has to open and regulate, so I think the OP's isn't that bad off.

You are not understanding. It's naturally open/unlocked. It will never fail closed/locked.

The seals fail, there is no longer enough hydraulic pressure to engage the clutch properly, it ends up slipping. Imagine driving a manual with the pedal half in. Sure, it moves, but it's creating a LOT of heat, and wearing fast.

[lswing]

You are not understanding. It's naturally open/unlocked. It will never fail closed/locked.

The seals fail, there is no longer enough hydraulic pressure to engage the clutch properly, it ends up slipping. Imagine driving a manual with the pedal half in. Sure, it moves, but it's creating a LOT of heat, and wearing fast.

Got it. It threw me when you stated the fact that the OP's TC not slipping is worse. Under load his is transferring power just fine, and driving fine it seems, that's all.

[ddillenger]

The issue is it's not a binary converter (on or off). It's regulated, modulating the clutch.

So while it might not slip during steady state operation, It can easily be slipping during engagement.

[lswing]

If you do get VCDS from Ross-Tech, you can actively log/observe the TC function. It's interesting to see when it locks, unlocks, regulates. Forget which data block it is, but just log the data and keep an eye on your laptop to see it in real time.

[agent5150]

I was going to get the APR programming done, but with this TC thing, I am not sure if that is a wise move at this time. APR has dropped the price on it.. now $599... very tempting. And my mechanic keeps bugging me.. "no RS6 that I know, is running without it.. you don't know what you are missing" I thought... sure he wants me to get APR, it will probably shorten the life of turbos/tranny etc... more business for him :P.. but it was the price in thousands of dollars that always put APR at a lower prioirty for me.

[lswing]

I was going to get the APR programming done, but with this TC thing, I am not sure if that is a wise move at this time. APR has dropped the price on it.. now $599... very tempting. And my mechanic keeps bugging me.. "no RS6 that I know, is running without it.. you don't know what you are missing" I thought... sure he wants me to get APR, it will probably shorten the life of turbos/tranny etc... more business for him :P.. but it was the price in thousands of dollars that always put APR at a lower prioirty for me.

Yep, I'd wait until the TC is sorted out or cleared as good. That's a good price and seems like a solid tune. Any of the tunes will put a great deal more stress on the TC and Trans, usually looking at +50hp/+100tq at a minimum, adding to a gearbox that can break under stock power. Most of it comes down to how you drive it, or beat on it...I've been through one TC and two Trans, lesson learned with too much hard shifting.