Slipping 3rd to 4th when hot...

[lswing]

Well, still acting up here, figured I'd post for some extra input...

Went out to log data on a warm day here, 85, had been driving around the city for a while so car was reading 90 on the display. First run in 3rd, Tip manual shift mode, shudders around 3,000 then pops into 4th around 4,500rpm, so much for logging, onto the problem.

Trans is 8 months old, upgraded A clutch pack after rebuild. Trans fluid flushed and confirmed filled to the top. Got some input from Tozo; I mentioned I had pulled the Aux radiators last year; he said trans fluid could be overheating/foaming and not being able to hold enough pressure to keep in gear.

Any other thoughts on why the fluid would be getting so hot?

Also for the first time got a trans code, scanned right when I got home; Trans Temp Sensor, reading implausible...hmmm, so that means it's hot I'm guessing, or just odd timing with a wiring issue. Car has full boost and more than enough power, too much apparently.

Also wonder if the notches we cut in the trimmed trans filter pickup might be adding to the fluid foaming? Don't know really. Thinking a flush with new fluid and filter, trim pickup just a bit this time, see how things look in there.

Just fishing, thanks for any ideas/input....

[kevin]

Sorry to hear. Cut your losses and install an 01E.

[lswing]

Sorry to hear. Cut your losses and install an 01E.

Thanks, but no can do, bad back keeps me from operating a clutch more than on the weekends. Maybe down the road...waiting 4-5 years for the RS7 to show up used for $40-50k, then the RS6 can be a track/toy and not daily.

Might just need more cooling, being optimistic. Drove the hell out of the car on many occasions this spring when it was cooler, no issues even after hours. I've certainly hit the clutch's hard on many occasions, and the car has great power, really hoping it didn't eat another trans, but only have about 200-300 hard shifts on it under full throttle...

[905084]

How hot is "hot" for the trans fluid temp when it skips? VCDS ...."Lite" will tell you the zach temp of the trans fluid. And the fluid in the trans is what? Need more info...

[lswing]

How hot is "hot" for the trans fluid temp when it skips?

Dunno, crap, should have checked it with VAG when I was out eh?

Car reading 90F on the dash, drove around town for 30 mins, then out to the highway...

[905084]

And, as far as I know from my experience (cause I suck with the TIP mode) it will upshift by itself, when it decides you didn't and you should have. Just like the paddle mode only lasts for so long till it decides to shift for you....

[mik15]

that sucks, but i don't really think is the oil temperature, by your description it does slip. My car was running here at 110-120F outside, even when the TC was bad never had issues with slipping and the gearbox oil temperature never went above 225F and that was on a track day, otherwise it was set at around 180-190F. At cca 250F the gearbox will go into limp mode. In manual mode it will only up-shift at red line, otherwise it will not do it.

Do a log while driving it to get a better reading of the gearbox oil temperature, it might after all be the cause if it gets too hot, though at 85F outside that doesn't really seem plausible, unless you've really beating the crap out of it.

But then again, if the Trans Temp Sensor is out, that could also be the culprit.

[DHall1]

I have my own issues with the A clutch. It's applied in 4th and 5th gear.

Dont know why that clutch would go first. Much more load on 1-2 and 2-3 shifts.

Aux coolers. Unless your coolant temps are rising and your car is overheating. It makes no difference if they are there or not. Coolant temp is determined by tstat.


Well, still acting up here, figured I'd post for some extra input...

Went out to log data on a warm day here, 85, had been driving around the city for a while so car was reading 90 on the display. First run in 3rd, Tip manual shift mode, shudders around 3,000 then pops into 4th around 4,500rpm, so much for logging, onto the problem.

Trans is 8 months old, upgraded A clutch pack after rebuild. Trans fluid flushed and confirmed filled to the top. Got some input from Tozo; I mentioned I had pulled the Aux radiators last year; he said trans fluid could be overheating/foaming and not being able to hold enough pressure to keep in gear.

Any other thoughts on why the fluid would be getting so hot?

Also for the first time got a trans code, scanned right when I got home; Trans Temp Sensor, reading implausible...hmmm, so that means it's hot I'm guessing, or just odd timing with a wiring issue. Car has full boost and more than enough power, too much apparently.

Also wonder if the notches we cut in the trimmed trans filter pickup might be adding to the fluid foaming? Don't know really. Thinking a flush with new fluid and filter, trim pickup just a bit this time, see how things look in there.

Just fishing, thanks for any ideas/input....

[lswing]

Really don't know...all else seems fine, get the car warm, and bam, screwed up shifting...

So maybe I've roasted the clutch already, or fluid and pickup aren't playing nice. I've put the hammer down full throttle shifting at redline 30-40 times, must be rough on the trans.

[ttboost]

Yep..stock transmission doesn't like anything other than just cruisin. I think there is more load on the transmission in higher gears...however, once it slips once, it's not gonna get better....sorry to hear. Mine started to slip in 4th, then 5th.... Never had a problem in 1st, 2nd or 3rd...
I suppose it's possible that different clutches fail at different times...just my thoughts...

[DHall1]

Got it. I did read a service manual for the ZF trans and there is a spreadsheet to diagnose trans problems. (A clutch) is applied in 4th and 5th only. When you have a problem with shifts in those gears only its the A clutch.

There is lots of torque applied between that 3-4 shift as the gear ratio is making a big drop to 1:1.


Yep..stock transmission doesn't like anything other than just cruisin. I think there is more load on the transmission in higher gears...however, once it slips once, it's not gonna get better....sorry to hear. Mine started to slip in 4th, then 5th.... Never had a problem in 1st, 2nd or 3rd...
I suppose it's possible that different clutches fail at different times...just my thoughts...

[lswing]

Well it does have upgraded clutch packs, I'd be surprised they would fail so soon. Driven almost all the time in Tip. I suppose we'll see once we check/replace the fluid/filter.

My previous trans slipped a few times from 3rd to 4th under full load, same thing, but it was a bit low on fluid. Topped it off and was good for another year.

I'm also wondering if something is wrong with the TC, slipping some maybe, heating up and bubbling the fluid.

So what I think is odd, everyday on a short steep hill, 2nd gear, I get what I consider an slip or maybe it's just the TC locking up?; go up the steep part with revs at 2,500 and then about half way up it catches and they go down to 2,000. So is this the TC spinning then locking up, or the clutches spinning then locking up?

[lswing]

Got it. I did read a service manual for the ZF trans and there is a spreadsheet to diagnose trans problems. (A clutch) is applied in 4th and 5th only. When you have a problem with shifts in those gears only its the A clutch.

There is lots of torque applied between that 3-4 shift as the gear ratio is making a big drop to 1:1.

All my hard shifting has been 1-2, 2-3....2-3 being a tough shift, maybe just toasted that group and 3 can't hold the power anymore. 3-4 is one clutch pack to another then right?

[coco]

I'm not sure if it's applicable here or not....

I drive my RS6 (80k+ miles on her) without no trans issues though I drive in hot and quite harsh traffic condition in Japan.

I installed ATF temp meter but it never goes over 95C even though driving through (not even "through" because it usually takes an hour to drive only 10miles in Tokyo, hahaha)"stop and go" and "bumper to bumper" situation in Tokyo with outside temp is pretty close to 100F.
So the temp is not the issue here but upgraded TC?

[ttboost]

I'm not sure if it's applicable here or not....

I drive my RS6 (80k+ miles on her) without no trans issues though I drive in hot and quite harsh traffic condition in Japan.

I installed ATF temp meter but it never goes over 95C even though driving through (not even "through" because it usually takes an hour to drive only 10miles in Tokyo, hahaha)"stop and go" and "bumper to bumper" situation in Tokyo with outside temp is pretty close to 100F.
So the temp is not the issue here but upgraded TC?

Is your car modified or all stock? If you are NOT flashed, you really shouldn't have a problem...if you are flashed...it's only a matter of time...

[lswing]

Yep, running the extra 125 Torque from the engine is a massive difference. But still, only have 3k on the upgraded trans. Will know a bit more today after new fluid/filter goes in. Filter pickup tube may have been trimmed too much, hoping that's part of it. Will see if the temp sensor code shows again.

I've done about 30 full throttle runs from 0-60, each time in Tip, letting it usually shift on its own at redline.

Again, this has only slipped twice, when warm, and 3rd gear full throttle in Tip.

[Bigglezworth]

Talk to the trans rebuilder. You're under a 1 year warranty timeframe. They should be able to address your concerns.

[TozoM8]

R=C and F clutch
N=F clutch
1st= A clutch
2nd= A and E clutch
3rd= A and D clutch
4th= A and B clutch
5th= B and D clutch
We are working on figuring it out. Too short filter, lack of trans cooler and/or faulty trans temp sensor (and all that extra muscle :) could cause the problem.

[lswing]

Thanks for the details, will report back later tonight, along with keeping an eye on the temp sensor code.

[MaxRS6]

^Bummer to hear about the issue- Good luck with a quick resolution

[Kgnast]

200-300 hard shifts under WOT over the last 8 or so months? I probably put 100-200 hard shifts on the car on my way back from CT after putting the MTM TCU in the car (thanks TTBoost!). You are a very well behaved individual in the RS6! That MTM TCU is awesome. I'd love to know what the difference is net in tenths on a 1/4 mile. My bet would be at least a tenth per shift.


Thanks, but no can do, bad back keeps me from operating a clutch more than on the weekends. Maybe down the road...waiting 4-5 years for the RS7 to show up used for $40-50k, then the RS6 can be a track/toy and not daily.

Might just need more cooling, being optimistic. Drove the hell out of the car on many occasions this spring when it was cooler, no issues even after hours. I've certainly hit the clutch's hard on many occasions, and the car has great power, really hoping it didn't eat another trans, but only have about 200-300 hard shifts on it under full throttle...

[lswing]

Well, off to a good start. Nothing much regarding clutch debris in the fluid. Back to stock fluid and 1/4" trimmed pickup on the filter. Got a nice drive in, two 3rd gear pulls to "60" and no shudder or slip to 4th. Day was cooler which could help a bit, but certainly better it seems.

I'll go for a drive soon and check trans fluid temps to see where it's at.

Current thinking is pickup trimmed too much, causing foaming of fluid, setting off temp sensor to read implausible, along with lack of pressure allowing the slip.

Time will tell, but makes me realize you only want to press so much power into the auto trans, rebuilt or not...

[ttboost]

200-300 hard shifts under WOT over the last 8 or so months? I probably put 100-200 hard shifts on the car on my way back from CT after putting the MTM TCU in the car (thanks TTBoost!). You are a very well behaved individual in the RS6! That MTM TCU is awesome. I'd love to know what the difference is net in tenths on a 1/4 mile. My bet would be at least a tenth per shift.

No problem bud..wish I had my car home...a ride in that would've changed everything....

[lswing]

And it's back....I added a bit more boost and fuel, car felt faster and great, then after warmed up good shuddered and slipped up to 4th during a 3rd gear pull. Other than that, all's fine...so how was the play Mrs. Lincoln?

Crap....not the worst if it will hold together. During normal acceleration the trans enters 3rd much higher rpm than when data logging, and has shuddered, but not slipped. If I start in 3rd, shudders good around 3,500 then pops around 4-4,500 up to 4th, goes about it's business and seems fine otherwise.

Makes we wonder about few things, and I'll have to email Tozo, but even this spring when I was doing some fast driving, I noticed the shudder from the trans. Maybe the VB is not putting enough pressure?...or do the upgraded clutch packs last longer but not have as much grip?

All seems well on a moderate tuned amount of power, but when I try and max out the tune, now with the Wagners making it a bit better, there goes the slip....

I can live with it, but it does inhibit data logging, seems to stick together otherwise. Fluid and filter topped off and good, never got a lot of particles so I don't think the clutch packs are shot, just not holding for some reason...if it lasts I'll be happy, but I would like to find a fix if possible to get that extra bit of power to the wheels...

[lswing]

Oh yes, Tran Temp sensor code intermittent is there all the time now...trans temps are not bad, reading around 200F during this....

[905084]

Does it slip when you power brake it when hot? Dirve....brake on.....run it up to the TC stall speed (~1800)....slips then slams?

[lswing]

Does it slip when you power brake it when hot? Dirve....brake on.....run it up to the TC stall speed (~1800)....slips then slams?

Hasn't before...but I'll give it another try this week. What you thinking?

[905084]

Mine (both Thing One and Thing Two) would slip if you power braked them when hot. Thing One was my first and what I learned was after she got hot, she would slip....sometimes in 1st, 2nd, 3rd, 4th....but never in 5th.....When she was cold she was ok.....but put some heat in her....after say 20-30 miles, she would slip. If she slips when hot as you run her up in first when you power brake her , I suggest it's the A-clutch oring....she will hold till about 1500 rpm, then slip....then slam back into gear...the trans may or may not go into limp mode....

[lswing]

Interesting, hoping something small like an o-ring isn't it...thanks for the testing tip.

Trans feels great all around, and never felt a slip when accelerating through gears...it's just that hard pull in third when starting lower in the gear...

[905084]

Live with it till it dies......that's my wife's theory.

[lswing]

Live with it till it dies......that's my wife's theory.

Only little problem is this is a brand new trans....well, 4k now....

[lswing]

Mine (both Thing One and Thing Two) would slip if you power braked them when hot. Thing One was my first and what I learned was after she got hot, she would slip....sometimes in 1st, 2nd, 3rd, 4th....but never in 5th.....When she was cold she was ok.....but put some heat in her....after say 20-30 miles, she would slip. If she slips when hot as you run her up in first when you power brake her , I suggest it's the A-clutch oring....she will hold till about 1500 rpm, then slip....then slam back into gear...the trans may or may not go into limp mode....

Were you tuned when this was happening? If I back the tune off a bit, trans holds, and still WAY faster than stock. Pressing the limits she starts to slip...

[905084]

Were you tuned when this was happening? If I back the tune off a bit, trans holds, and still WAY faster than stock. Pressing the limits she starts to slip...

Both tuned....Thing One is Sportec....Thing 2 is GAIC.....both pushing a little over 500 I guess.....I flog Thing 2 daily as she is mine....3k on a trans, T/C I got off eBay for $600......

[lswing]

Well, shudder is what I've got...

http://www.lubegard.com/SearchByCategory.aspx?CategoryCode=230&title=Dr.+Tranny+Instant+Shudder+Fixx#

[DHall1]

Lou,

I just noticed this post on rs246.com. Owner was having trans problems and noted that the TC would not lock with trans temp sensor failure. It may be worth lookking into...

ATF temp sender so the TC wouldn't lock. So, I sent the VB off to 517trans and they rebuilt it. MRC replaced the VB loom and also found the engine oil overfilled by AmD. They also rectified a leak to the turbos with engine in situ which AmD wanted to perform an engine pull.
The car has been on the dyno without any gearbox slip and a test drive didn't find any slip either, so I'm very happy.
It'll be painful getting back into the 'loon, I'm sure a manual in the C5 is just wrong, it's great on track but everywhere else I'm sure the tiptro comes out on top.


Well, still acting up here, figured I'd post for some extra input...

Went out to log data on a warm day here, 85, had been driving around the city for a while so car was reading 90 on the display. First run in 3rd, Tip manual shift mode, shudders around 3,000 then pops into 4th around 4,500rpm, so much for logging, onto the problem.

Trans is 8 months old, upgraded A clutch pack after rebuild. Trans fluid flushed and confirmed filled to the top. Got some input from Tozo; I mentioned I had pulled the Aux radiators last year; he said trans fluid could be overheating/foaming and not being able to hold enough pressure to keep in gear.

Any other thoughts on why the fluid would be getting so hot?

Also for the first time got a trans code, scanned right when I got home; Trans Temp Sensor, reading implausible...hmmm, so that means it's hot I'm guessing, or just odd timing with a wiring issue. Car has full boost and more than enough power, too much apparently.

Also wonder if the notches we cut in the trimmed trans filter pickup might be adding to the fluid foaming? Don't know really. Thinking a flush with new fluid and filter, trim pickup just a bit this time, see how things look in there.

Just fishing, thanks for any ideas/input....

[lswing]

Lou,

I just noticed this post on rs246.com. Owner was having trans problems and noted that the TC would not lock with trans temp sensor failure. It may be worth lookking into...

ATF temp sender so the TC wouldn't lock. So, I sent the VB off to 517trans and they rebuilt it. MRC replaced the VB loom and also found the engine oil overfilled by AmD. They also rectified a leak to the turbos with engine in situ which AmD wanted to perform an engine pull.
The car has been on the dyno without any gearbox slip and a test drive didn't find any slip either, so I'm very happy.
It'll be painful getting back into the 'loon, I'm sure a manual in the C5 is just wrong, it's great on track but everywhere else I'm sure the tiptro comes out on top.



Very interesting, thank you sir! Checking in with Tozo on this. I'll try some driving with the laptop and watch for it to close. Odd enough this whole year it seems like the TC has been slow to lockup on hills, hmmm...

[lswing]

Logged TC into work, opens and closes fine according to logs and watching live data...

[lswing]

Lou,

I just noticed this post on rs246.com. Owner was having trans problems and noted that the TC would not lock with trans temp sensor failure. It may be worth lookking into...

ATF temp sender so the TC wouldn't lock. So, I sent the VB off to 517trans and they rebuilt it. MRC replaced the VB loom and also found the engine oil overfilled by AmD. They also rectified a leak to the turbos with engine in situ which AmD wanted to perform an engine pull.
The car has been on the dyno without any gearbox slip and a test drive didn't find any slip either, so I'm very happy.
It'll be painful getting back into the 'loon, I'm sure a manual in the C5 is just wrong, it's great on track but everywhere else I'm sure the tiptro comes out on top.



Dave, if you get a chance can you direct me to this thread?

I think the trans slipping started happening about the time the code for trans temp sensor was thrown. Don't think I had any codes before that. I had a bit of shudder, but no codes. Could be that the power is already loosening the clutches up a bit too in worse case scenario.

Getting the temp sensor wiring inspected next week...if that doesn't do it the damned thing is in the VB, more trans fluid, yay!

[ttboost]

Shudder is slipping...death knoll...not gonna get better...it will start in higher gears (more load) and work it's way down. If it's doing it in lower gears now..not good. If you wanna keep it an auto, send it to 517 Transmission. He told me he custom fabs parts to make it stronger and last longer. Don't ask me what parts, but everyone seems to be happy with his work.

[DHall1]

Where is the temp sender located? Crap, I didn't save the link....its one of the big posters on the board over there....and it was not in a general trans thread. Lemme think about it a sec...

ok back...

down at the bottom of the page. bambam

http://forum.rs246.com/viewtopic.php?f=2&t=89022&start=330


Dave, if you get a chance can you direct me to this thread?

I think the trans slipping started happening about the time the code for trans temp sensor was thrown. Don't think I had any codes before that. I had a bit of shudder, but no codes. Could be that the power is already loosening the clutches up a bit too in worse case scenario.

Getting the temp sensor wiring inspected next week...if that doesn't do it the damned thing is in the VB, more trans fluid, yay!

[lswing]

Dave, trans temp sensor is in the valve body, sweet right! We'll check all wiring out to the TCU first. Thanks for the linkage...

[lswing]

Shudder is slipping...death knoll...not gonna get better...it will start in higher gears (more load) and work it's way down. If it's doing it in lower gears now..not good. If you wanna keep it an auto, send it to 517 Transmission. He told me he custom fabs parts to make it stronger and last longer. Don't ask me what parts, but everyone seems to be happy with his work.

True to some extent....both of my trans have always shuddered under max torque in 3rd, both have only slipped 3rd to 4th. The previous trans blew itself apart in 2nd gear at 89k and was clunky and done after that. The old trans only slipped gear once, was low on fluid, done 7 months later.

The new trans has always shuddered some under max load. I've got this thing tuned strong, and just pushed the new trans over the edge by increasing the tune again, is my belief. I could pull a bit of timing and it should hold, but a bummer to not utilize the power. This one is running an upgraded clutch pack and other goodies, so I'd be surprised if it tore apart after 4k and 300 WOT runs...but you never know! I figure one good sign is no clutch material in the pan yet. Never launched, probably about 15 days were I really drove the piss out of it on back country roads.

As far as custom parts I'm sure 517 has some good stuff. Talking with Tozo he said there is no more room in the A drum for more or bigger clutches than he's already added. This should be stronger than stock, but my power levels are up also.

Again, always attributed the shudder to clutches slipping some, but the jump in shifts is when they break loose, and could be good for a long time even after that, with any luck!

Edit; 4-5 are on clutch pack B, so why do you think it would start there and work down to clutch pack A 1-3, if they are separate clutch packs? Unless it's another part that wears? I'll have to look at the trans diagram again. Maybe that jump from pack A to B is a weakness. And yes, auto trans only for me, bad back unfortunately.

[4everRS]

Temp sensor plugs into the valve body. I blame a faulty temp sensor on ruining the tc on my Daytona car. I have to agree with mike on this. Anything you do will be a bandaid, until you do a full r&r.

A faulty brake switch will cause the tc to stay open as well.

[SensoRS6]

Well, shudder is what I've got...

http://www.lubegard.com/SearchByCategory.aspx?CategoryCode=230&title=Dr.+Tranny+Instant+Shudder+Fixx#

I think I have shudder as well. But it's only under WOT, but no slipping, think just too much power. Think this stuff would help?

[lswing]

Temp sensor plugs into the valve body. I blame a faulty temp sensor on ruining the tc on my Daytona car. I have to agree with mike on this. Anything you do will be a bandaid, until you do a full r&r.

A faulty brake switch will cause the tc to stay open as well.

Thoughts on why the trans temp caused your issue? Just did a full rebuild, $7k every 4k doesn't seem good, might have to tune it down a bit...

[lswing]

I think I have shudder as well. But it's only under WOT, but no slipping, think just too much power. Think this stuff would help?

Might, going to try it. My shudder only at wot at max torque, a few slips so far on this new trans. Old one only slipped once, then was fine for 7 months, go figure...

[4everRS]

Thoughts on why the trans temp caused your issue? Just did a full rebuild, $7k every 4k doesn't seem good, might have to tune it down a bit...
The temperature is not as relavent as what that sensor is telling the valve body to do. If it's sensing too hot (faulty) it will keep the tc open more. The sensor is the whole wiring harness at the trans.

[lswing]

The temperature is not as relavent as what that sensor is telling the valve body to do. If it's sensing too hot (faulty) it will keep the tc open more. The sensor is the whole wiring harness at the trans.

Interesting, similar to what could be happening here, TC not closing soon enough allowing too much power in, also overheating fluid. Could have sworn Tozo said sensor was in actual valve body.

[4everRS]

Interesting, similar to what could be happening here, TC not closing soon enough allowing too much power in, also overheating fluid. Could have sworn Tozo said sensor was in actual valve body.
It's a sensor wire that sort of wraps in/around the valve body. It's connected to the whole harness and doesn't seem to be removable seperatley. I guess you could call it "in" the valve body, I don't know. I think I have a pic somewhere.

[lswing]

That would be just great, fried TC or trans because trans temp sensor goes bad and doesn't throw CEL....we'll get the sensor resolved in the next few weeks and go from there, thanks!

[lswing]

It's a sensor wire that sort of wraps in/around the valve body. It's connected to the whole harness and doesn't seem to be removable seperatley. I guess you could call it "in" the valve body, I don't know. I think I have a pic somewhere.

Yep, embedded in the wiring then through the VB. Going to pull and replace in a few weeks. Anybody got the part # handy? don't have etka installed right now. I can check with Tozo also, hoping it's just a pan drop and VB can stay in the trans. F@&$cking sensor/wiring, arghhhh.....

[lswing]

Just an update from rs246, working out same issue....

I haven't driven it personally after the fix, but Doug @ MRC said there were no issues with slip post VB loom replacement (this includes the G93 ATF temp sender). The car also sent a fair bit of time on the Dyno trying to troubleshoot a meth kit failure, the Dyno usually exposes gearbox issues.
There was some top-end slip on WOT but then the sender failed and the TC wouldn't lock up so it was a pretty smooth but slow drive. However, instead of just replacing the loom I opted for betterment and used the chance to have the VB uprated by 517trans. So, the slip issue may have been rectified via better line pressure etc. For reference my 'box is a lowish mileage rebuild but recieving a tad more power than yours - 605PS/853Nm.

[DHall1]

Yes, this is good information. I was looking at your logs and noticed that it spends a fair amount of time in regulating phase. I don't know if this is a good thing because the TC is not locked and the clutches are attempting to apply and lock.

I was going to log the TC in my #1 car today as I drove it to work. Remembered the laptop but not the cable. Doh

Dammit, I wanted to run some logs because I filled up with a mixture of 1/2 91premium+Aces and 1/2 100 octane pure gas. I was ready to add timing and 2psi boost and have some fun. Dammit.


Just an update from rs246, working out same issue....

I haven't driven it personally after the fix, but Doug @ MRC said there were no issues with slip post VB loom replacement (this includes the G93 ATF temp sender). The car also sent a fair bit of time on the Dyno trying to troubleshoot a meth kit failure, the Dyno usually exposes gearbox issues.
There was some top-end slip on WOT but then the sender failed and the TC wouldn't lock up so it was a pretty smooth but slow drive. However, instead of just replacing the loom I opted for betterment and used the chance to have the VB uprated by 517trans. So, the slip issue may have been rectified via better line pressure etc. For reference my 'box is a lowish mileage rebuild but recieving a tad more power than yours - 605PS/853Nm.

[lswing]

Sounds like a nice fuel mix there, better get to use on it! Would like to see a TC log if you get a chance. Mine is only at 50% throttle, but is does seem to stay in regulating for a while. Yep some good info from these fellas, here's another one. I'll know more in a few weeks once Temp sensor/sender is fixed.

The temp sender could be a red herring, although, if your TC is locking late, that ain't good either. Having too much engine speed in viscous mode then only to lock up would put a lot through the clutches in one hit.

[DHall1]

Yep agreed. Some of those guys are pretty sharp if you can get around all the quips back and forth. One guy(footlong) has a link to just about every Audi service guide and bulletin on our cars.
Sounds like a nice fuel mix there, better get to use on it! Would like to see a TC log if you get a chance. Mine is only at 50% throttle, but is does seem to stay in regulating for a while. Yep some good info from these fellas, here's another one. I'll know more in a few weeks once Temp sensor/sender is fixed.

The temp sender could be a red herring, although, if your TC is locking late, that ain't good either. Having too much engine speed in viscous mode then only to lock up would put a lot through the clutches in one hit.

[lswing]

Was finally able to clear code, not sure why it wouldn't clear last week. Just sitting in the driveway running, temp readout seems fine, sat for 10 mins no issues. Makes me think it's the wiring where it plugs into trans body. Tozo has suggested that could be it, and from him and reading, the temp sensor itself in the VB hardly ever fails. The wiring into the trans from the tcu is exposed to the elements, and I'm thinking when I drive it jiggles around and causes the intermittent reading, will check it out this week.

[lswing]

Two days driving and still no trans temp code, although I've only gone 30 miles...some codes can take 50-100 to show I believe, so I'll check later this week. VAGCOM can read trans temp the whole time when I drive around with the laptop. Maybe the loose cable is just settled in place for now.

[lswing]

More of my current goose chase from a few years ago...just bumping for info.

[orcars6]

If you look at my previous thread....and lswing has responded numerous times, didn't know we had so much in common! As described, my tranny started exhibiting this slip thing only 2 weeks ago from 0 and has progressed nicely in a bad way to not only slipping when launching from 0 speed but now will slip 1st. 2nd. and 3rd. It is more evident on an incline/ up-hill etc. Goes back to Stealership tomorrow to see if they are the culprit after axle leak fix just a week before this problem. 2 yrs. no problem with tranny on launch or even massive spirited 'kick down' ....I am frustrated as hell at this point. Yes, we will check fluids and more and then what $$$!

[SteveKen]

I apologize ahead of time, as it might have already been covered.

Hot suggests that it could be a result of the fluid being less viscous. Fluid leaking past a seal or seals when hot, perhaps?

The same reason why things get worse after a fluid change.

Has anyone looked into using the Lubegard Red additive?

[lswing]

Thanks for the input. I should have clarified car is driving just fine, trans seems fine, it's just the sensor part that has shown up.

So I just randomly got the Trans Fluid Temp Sensor G93 intermittent during a scan. As stated in my other post, I got the same thing last year with my OLD trans. Can't believe I'd get this again on another trans, but I have seen it pop up a handful of times here and for the Euro group. Maybe the sensor is getting old, along with the rest of the car:)

I have barely driven the car this year as I'm just down in Texas for one year and I'd prefer to have a known mechanic nearby for issues. I've got ~800 miles or so, just a few freeway trips and spins around town/countryside, all super easy driving really.

I'll do some monitoring of the TC locking up and trans temps. When I had this same issue last year, I found it after the trans was already slipping, and it was slipping at any temp after more testing. This can be a dangerous code/issue as the temp sensor regulates the locking of the TC.

[lswing]

I'm going to log transmission block 007, which has the trans temp G93 along with the TC lock/reg/open status. So far just looking at it idling the trans temp reading is fine.

What should a good operating temp be for the trans fluid, along with a max temp (around 200C I think). Sitting in the driveway at warm idle the fluid is at 66C.

[fukinavit]

I'm going to log transmission block 007, which has the trans temp G93 along with the TC lock/reg/open status. So far just looking at it idling the trans temp reading is fine.

What should a good operating temp be for the trans fluid, along with a max temp (around 200C I think). Sitting in the driveway at warm idle the fluid is at 66C.

max not 200c, that's for sure. maybe 200f, I read somewhere when I used to own a pickup and towed a fair bit that once tranny fluid hits around 225f it should be changed as the temp degrades the oil.

[lswing]

max not 200c, that's for sure. maybe 200f, I read somewhere when I used to own a pickup and towed a fair bit that once tranny fluid hits around 225f it should be changed as the temp degrades the oil.

Yep, thanks for the reminder. I'll keep an eye on it when driving. Here's Google's generic feedback...

It doesn't take long for the automatic transmission fluid (ATF) to heat up once the vehicle is in motion. Normal driving will raise fluid temperatures to 175° F, which is the usual temperature range at which most fluids are designed to operate.

[lswing]

So if I'm at 66C in my driveway at idle on a warm day, without any driving, there doesn't seem to be much wiggle room before I get to 93C, which would be around the max desired operating temp of 200F.

Can someone else check temp at idle just so I have reference of trans fluid temp? Or temp after driving too, any numbers would be good.

[hahnmgh63]

I can run a log when I get home Lou if somebody doesn't pipe in by then. But that won't be until Wednesday.

[lswing]

I can run a log when I get home Lou if somebody doesn't pipe in by then. But that won't be until Wednesday.

Thanks. I'm traveling for a few days here also. I'd be interested in your idle temp and peak temp if you get a chance to glance at it. I'm assuming is a loose connection in the wiring harness at this point but will keep an eye on it as I don't want to risk it.

[G2]

A new Drive Cycle may be needed for the I/M status to update any trans codes. Unless it's a hard code, and will/can flag a MIL/DTC immediately.

The temp sensor code seems to coorelate to hard or sporadic shifting from what I've seen on a couple RS6's. 5th to 4th kick down can act up, or flare. Sensor is imbedded into wiring harness-- harness is $800+ from dealer. Last I knew had to be sent from the Mother Land.

Fluid flow issues are unlikely to be root cause. Would cause consistent shifting quirks. I have reshaped several filter pickups w/o issue. All edges should be smoothed and rounded. Last one came out obviously hacked, yes, hacked with a, yes, Hack SAW. Not deburred, not even a straight cut (courtesy of a "pro" audi shop....); Plastic danglies waiting to get sucked into the filter/trans... WTF...... (the critical tech in me says, you get what you pay for...usually.)

Maybe wise to remove valve body or shift selenoids. Check screens for debris. Pressure selenoids can get old and not work so well also.

LSWING- my custom ATF blend works nicely. Amsoil of course. Tried Version 2.0 in Chung's RS6 (higher mix ratio), seemed to help. Think his car has the temp sensor issue also, however. My car doesn't. Going with V2.0 or maybe 2.5 in my car this summer (4th gear slips in the winter, until fluid warms up; I Tip past it). Still wonder if it REALLY has a TCU tune....the MTM tune works great, holds a gear nicely before kicking down.

Doubtful any modern auto trans car (German anyways) runs anywhere near 175F. Higher. With that said the RS6 has 2 trans coolers/heater. The radiator (pre-heater) and the FMOC, which is integrated into the engine oil cooler. ECT on this car is much lower than newer German cars (lowers trans temp), plus the big external oil cooler. So maybe 180-220 is realistic. Shouldn't be any issues fluidwise until 260+F, maybe a bit more depending on brand of fluid.

Wiring harness plug: They don't wiggle, or shouldn't. The o-rings leak at the case pass-thru. Could contaminate the harness plug. I use electrical contact cleaner, wash and dry it out, add dielectric grease, ensure rotating plug sleeve is fully engaged.

All I can think of right now. Lovely A5 full of DTC's no one else can figure out....see how that goes. The newer these cars get the more I like the "old" ones.

[Other_Erik]

Sorry to the OP, I can't offer anything useful...

Gary, why can't you live less than 2,000 miles from me? Could use a good RS6 mechanic in the DC area, everywhere I've been just wants to throw parts at problems :|

Side note - anyone with this problem ever get a code thrown (don't remember it off the top of my head) something along the lines of the TCU not knowing what gear you're in? Saw that one once, and I rarely get a chance to stretch my beast's legs, so it's not from hard shifting...

Thanks
O_E

[hahnmgh63]

If you mean the TCU not knowing what gear your in by the dash cluster going reverse highlighted? If so that is the Limp mode for the TCU, usually sticks the car in 3rd gear so you can get going with a bit of TC slip from a stop but obviously limited in top speed.

[Other_Erik]

If you mean the TCU not knowing what gear your in by the dash cluster going reverse highlighted? If so that is the Limp mode for the TCU, usually sticks the car in 3rd gear so you can get going with a bit of TC slip from a stop but obviously limited in top speed.

No sorry not what I was talking about, I'll have to pull up the scan to get a copy of the code it threw. There were no adverse affects while driving, drove like normal, with the damn CEL lit because of the generic "Cooling System Malfunction" code - pulled full scan and there was a code with some wording along the lines of "Unable to determine current forward gear - Intermittent", was quite odd, never seen it before or since. I have been doing logging while driving, and scans before/after every drive trying to determine what in the blue bleeding fxxk is causing P2181-008. Maybe car computer is just tired of me asking it to dump all logs to the Vag-Com :)

Anyway, back to the issue at hand - gear slip while trans is hot. I'm no ASE master mechanic, but it does sound like degraded fluid to me. Maybe someone can chime in on how to pull a sample for blackstone labs to test without too much disruption to the trans?

Blackstone helped me immensely with my old Pontiac, diagnosing a crank position sensor failure. Car would start, run, drive, everything happy until full operating temperature, then it would stall and refuse to start until cooled off. Turns out the replacement CPS done by a local shop, they'd screwed it in too far, and after everything heated up it couldn't track the crank anymore (full systems shutdown, no code thrown). They managed to figure it out from a trace of (Tungsten? I forget which metal they use for the CPS) in the oil, turns out the sensor had been clipped by the crankshaft, probably caused the first time it stalled out and then every time afterward.

---ramblerambleramble---

O_E

[G2]

[QUOTE=Other_Erik;273721

Anyway, back to the issue at hand - gear slip while trans is hot. I'm no ASE master mechanic, but it does sound like degraded fluid to me. Maybe someone can chime in on how to pull a sample for blackstone labs to test without too much disruption to the trans?
O_E[/QUOTE]


-- Fluid is usually a good starting point. Nearlly all issues are fluid related and/or fluid flow related (old fluid clogs the filter). Or the oil shears down. My beater Jeep shifted so much better after a trans service and fluid flush (Dex3 since it was sitting aground- works great...filling with Amsoil would exclipse the price of the vehicle).

Most trans have external ports for testing pressures. Some what odd, your symptom....mine slips when cold, and is fine when hot. Some 5HP24's slip when hot in 4th. The one I recently serviced was, I thought, much better with my ATF blend. Didn't "fix" it,but better. 4th gear, i think, sees the most torque loading. Throwing 500-550lb/ft at a 415lb/ft trans that's a dozen years old is asking a lot.

There is a trans pan drain plug. Easy to drain a bit out. Just keep in mind that's where most of the crud is. That magnets catch the big stuff, however.

Not knowing what BlackStone charges? The Amsoil KIT06 (UOA kit) is the cheapest they offer. Wholesale is about $20. Should be on my website www.oiloregon.com
Oil Analyzers does the UOA. Nice on-line system.

Either way a report would be interesting to see. And thanks for the comment.

---ramblerambleramble---

[lswing]

So if I'm at 66C in my driveway at idle on a warm day, without any driving, there doesn't seem to be much wiggle room before I get to 93C, which would be around the max desired operating temp of 200F.

Can someone else check temp at idle just so I have reference of trans fluid temp? Or temp after driving too, any numbers would be good.

Grabbed a temp reading when I got home from doing some errands and stretching of the legs. 90 degrees F out today in central, TX. Car read 91C for the trans fluid temp once I was in the driveway. Puts me at 196F. Temp code for intermittent G93 sensor is back right away.

Seems reasonably warm for how hot it was. I'm always amazed the carbon on the air box isn't completed cracked and fried. If I was really out doing some spirited driving I would assume the trans fluid temp would reach at least 220F, based of my moderate driving today.

My plan is to take it easy until I move later this summer and find a new mechanic. I guess we'll check all connections like last time; and then replace the G93 like last time; and maybe all will be good.

[Other_Erik]

Grabbed a temp reading when I got home from doing some errands and stretching of the legs. 90 degrees F out today in central, TX. Car read 91C for the trans fluid temp once I was in the driveway. Puts me at 196F. Temp code for intermittent G93 sensor is back right away.

Seems reasonably warm for how hot it was. I'm always amazed the carbon on the air box isn't completed cracked and fried. If I was really out doing some spirited driving I would assume the trans fluid temp would reach at least 220F, based of my moderate driving today.

My plan is to take it easy until I move later this summer and find a new mechanic. I guess we'll check all connections like last time; and then replace the G93 like last time; and maybe all will be good.

hmm... Moderate driving, even at 90F ambient should not put trans fluid at 196F, unless you've removed the warm weather package secondary radiator. I'm not saying that that _is_ the issue, but heat-soaking the trans would worry me a lot. Spirited driving would probably put you in the 250F region depending how long you keep your foot in it. I see in your sig you say Aux Radiator Delete - you mean the secondary oil coolers from the backs of the stock IC's, not the transmission cooler mounted on the main radiator, right? We may have found our culprit, even if you still have the trans cooler hooked up - assuming it's still there, have you flow-tested it? Enough gunk buildup from 12 years of spirited driving may have plugged the rad line, giving a plausible reason your trans runs so hot.

Regarding the G93 code you're getting - I love how word order can make a difference, especially when translated from Deutsche.
G93 Sensor temperature high warning intermittent
Is completely different from
G93 Sensor intermittent temperature high warning

The first means your temperature intermittently spikes high, while the second means your sensor intermittently fails signal at higher temperature.

I need to modify my sig to note that I'm not an expert, I'm basically doing guesswork based on second-hand knowledge of the integrated systems of this car. Take everything I say with a massive grain of salt and listen to the real Pro's here.

O_E

[lswing]

hmm... Moderate driving, even at 90F ambient should not put trans fluid at 196F, unless you've removed the warm weather package secondary radiator. I'm not saying that that _is_ the issue, but heat-soaking the trans would worry me a lot. Spirited driving would probably put you in the 250F region depending how long you keep your foot in it. I see in your sig you say Aux Radiator Delete - you mean the secondary oil coolers from the backs of the stock IC's, not the transmission cooler mounted on the main radiator, right? We may have found our culprit, even if you still have the trans cooler hooked up - assuming it's still there, have you flow-tested it? Enough gunk buildup from 12 years of spirited driving may have plugged the rad line, giving a plausible reason your trans runs so hot.

Regarding the G93 code you're getting - I love how word order can make a difference, especially when translated from Deutsche.
G93 Sensor temperature high warning intermittent
Is completely different from
G93 Sensor intermittent temperature high warning

The first means your temperature intermittently spikes high, while the second means your sensor intermittently fails signal at higher temperature.

I need to modify my sig to note that I'm not an expert, I'm basically doing guesswork based on second-hand knowledge of the integrated systems of this car. Take everything I say with a massive grain of salt and listen to the real Pro's here.

O_E

Good input, thanks.

We removed the Aux Radiators just after I got the car, they just flow engine coolant through them. Took about a year or two for the G93 sensor code to show after that. But I would agree that these have an effect on overall temp, cooling of the engine coolant would help keep other fluids a few degrees cooler.

You mentioned what I've been thinking, that my trans cooler up front is not flowing correctly. That would be a very reasonable explanation for this same code two times in a row now. I'm getting the G93 Sensor intermittent signal (don't think it says anything about high temp, but I will confirm), and this either gets activated at 90C+ or is faulty. Since I've now had the same code on two separate transmissions it makes me wonder. We did purge the whole trans cooling system a while back and fluid seemed to flow fine though.

The temps from this last log were basically a grocery getter run, on a warm day, with a few miles of highway. I could and would typically drive the car WAY harder, so I think that trans temp could really escalate.

I'm going to try a few start and idle sessions in the garage, 15 minutes each time, to see if the G93 code pops back up. It does not throw a CEL by the way, just sits there stored for some reason.

[Other_Erik]

Good input, thanks.

We removed the Aux Radiators just after I got the car, they just flow engine coolant through them. Took about a year or two for the G93 sensor code to show after that. But I would agree that these have an effect on overall temp, cooling of the engine coolant would help keep other fluids a few degrees cooler.

You mentioned what I've been thinking, that my trans cooler up front is not flowing correctly. That would be a very reasonable explanation for this same code two times in a row now. I'm getting the G93 Sensor intermittent signal (don't think it says anything about high temp, but I will confirm), and this either gets activated at 90C+ or is faulty. Since I've now had the same code on two separate transmissions it makes me wonder. We did purge the whole trans cooling system a while back and fluid seemed to flow fine though.

The temps from this last log were basically a grocery getter run, on a warm day, with a few miles of highway. I could and would typically drive the car WAY harder, so I think that trans temp could really escalate.

I'm going to try a few start and idle sessions in the garage, 15 minutes each time, to see if the G93 code pops back up. It does not throw a CEL by the way, just sits there stored for some reason.

NP. Do you have a block log with trans temp from a regular drive? Compare engine coolant temp gradient to trans temp gradient.

Engine coolant should show a steady uptick, followed by a valley after it peaks at/just over your thermostat temp (thermostat opens), then temperature gradients depending on engine speed. Should end up looking like a peak, a valley, then shortwave peaks and valleys as the radiator and water pumps do their jobs.

Trans temp should show steady uptick from cold to operating temp (170F or so), then short peaks and valleys as you drive. If all you see is a peak followed by steady temperature with no valleys when you're idle-cruising, chances are you've got a flow problem in the cooling loop of the trans fluid.

If the code for G93 Sensor Intermittent Signal happens to coincide with peaks in the actual trans temp, it may actually be heating to the point that the TCU rejects the sensor signal (not sure of the temp peak for this sensor) - let's say for sake of argument the maximum temperature signal the TCU accepts is 250F (121C) - if you hit 255F or higher, the sensor will be sending what the TCU sees as "Implausible Signal" - which could happen intermittently as the trans temperature fluxuates back under and over the 250F mark.

TL;DR version: Go for some moderate drives, log engine coolant temp and trans temp blocks, let's see what the pretty little graphs show. If you see peaks with flat caps, you may be overheating the trans to the point the TCU doesn't recognize the signal.

O_E

[lswing]

^^^Good call. I'll go out and log some data in the next week or so and report back. Thanks again for the good ideas and helping me think out a good troubleshooting process.