Slipping 3rd to 4th when hot...

[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.

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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.

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