george J

I took my '07 A6 out for its second opentracking day recently and got more insight into a problem with the shift paddle changes ("sport mode"). It appears that for the first 15 minutes the tranny changes as directed, but then for the 2nd half of the session it develops a mind of its own: not changing from 3rd to 2nd when paddle pressed (although repeated attempts succeed), and shifting from 2nd to 3rd and from 3rd to 4th when not pressed. I'm driving with traction control in competition mode. The changes (requested and forced) are happening below the max speeds listed in the Owners Manual -- and I'm driving the same in 2nd half as 1st half. One idea I had is that perhaps some automatic override kicks in when active handling has kicked in, or ABS has kicked in, or the tranny temperature is too high (mine got to 175 with ambient temps of 105 -- despite a Ron Davis radiator ...)

Any ideas? Thanks.

davidfarmer

that simply goes to show that it's still an auto, no matter what kind of paddles/buttons they put on it. I suspect it is temperature related, either directly or electronically over-riding.

Just like with a manual, you should not be downshifting until the very end of your braking zone. You want the revs as low as possible when you make the shifts to prevent over-revving. Assuming this is all being done, then temps can certainly change the behaviour of any hydraulic fluid.

If you are going to continue to track this car, I'd simply concentrate on improving your driving style. IE work on being smooth with your hands and feet, and let the trans do as well as it can. You certainly can't force it to shift if the TCM won't let you.

btw, 175 doesn't seem that high to me. However, maybe an external trans cooler (in addition to the integral unit) would help. Since you are only seeing 175 when your coolant temps are certainly much higher than that, I imagine an air-to-ATF cooler would be much more effective.

Tintin

David is correct, 175 is not that high in Farenheit... My Suburban trans temp readout is that high on my commute to my business every morning..
Maybe the computer goes into protect mode or some such when you hit some rev parameter over a set time frame? Many of the current autos have bizzaro behaviour when the program does the thinking.. try left foot braking to set the front end in a high speed corner in a new 3 BMW for example and see what happens... make sure there is nothing to whack into nearby when you give that a test...
look below for the exciting consequence








The bloody thing will floor the brake pedal and not let go until the car stops because the car thinks the throttle is stuck open... this whilst you have the throttle floored... exciting offroading follows immediately because of the loss of balance... did this on an offramp at 100 mph.. no rails , just nice smooth grass to fly over... the sales guy was a little pale and wanted to end my test drive... didn't buy the car, too weird for me...

2000BSME

I had to get HPTuners and program my a4 to act right in my '99.

mousecatcher

huh, never considered that. i like to downshift as soon as possible in case of a missed blip.

Allthrottleandsomebottle

I would try it with all traction control/comp mod off.
May be some interesting algorithms delaying shifts from the factory tune with any driver aids still on.
I am running dex VI trans fluid in my 97’ which is the same as in yours…….my last temps were 274 at the end of a session( was beating on it in hot weather at VIR) so no worries on your temps. Maybe……… over 240 could cause shift issues on a stock tune.
I have played with a stock C6 paddle shift coupe and it worked pretty good………but I did have all the drive aids turned off………trans temp 200+
PS, I downshift after the braking zone..........

AU N EGL

Brakes are for slowing your car down, not the transmission. That is why as David mentioned, downshift just prior to turn in.

The computer has certain algarythums that allow you to downshift in a very narrow rpm range. PPL who have learn that narrow range plus downshift at the last moment, before turn in have not had a problem traking the A6.



Rember brakes are less expesnensive to replce over a transmission.

george J

Whoops I meant to say 275, not 175!

I'm a pretty good driver (although I say it myself!) with a race car as well so this is just for casual fun with my street car, I knew it would be suboptimal when I bought an auto (much easier to drink coffee on way to work:-))

But the main point is that nothing is changing -- on the car or my driving -- between the 1st half and 2nd half besides the temperature so sounds like there's some unadvertized fail-safe mechanism kicking in before the documented overheating mode kicks in (at 325 oil temp I think).

rbl

Well David I will certainly disagree with you.

We have about 15 events on this car and I'll tell you that it will shift on demand as smooth or smoother than you can with the M6 and probably as fast for the cycle. In fact, when Norbert rode with my wife he actually had to ask her if she was shifting.

George .... it sounds like your trans is messed up or it may have an issue when it gets hot. We have had no issues and we have had a few C6's.

When it is in that mode it WILL NOT shift on it's own. I would have it looked at.

george J

Rex, glad to know I'm not the only one tracking an A6 and that your experiences are all positive! It really is a great car.

Have you experienced high tranny temps like mine (275)?

You're not completely correct that the shift paddles always do their bidding -- on p.99 of Manual it says when they don't (to save the engine from over-revving on the down shift and lugging on the up). I have seen the "X" in the picture. However it's not downshifting at safe speeds (and it's upshifting without my bidding) so there's something else going on. Interestingly the Manual also says that traction control slows the upshift.

So I guess my next step is to talk to the dealer and also try without any traction control (that should be interesting as the articles I've read recommend competiition mode even with professional racers.)

I really don't want to add another cooler. I added a separate oil cooler and a Ron Davis water/tranny cooler and two+ thousand dollars later the oil temp went from 300 to 285 (good) but water/tranny went from 220/265 to 240/275 [ambient went from 90 to 105] -- disappointing!

rbl

When you get the thing in Sport it will run as an automatic until you manually shift it one time. Then it will "act" like a manual but no clutch.

We always run in Comp Mode ... yea, real men turn it all off ... Comp mode truns off traction control but leaves active handling in place.

It will not up-shift (on it's own) after that. It will hit the rev limiter and stay there.

If you try to downshift out of range it won't let you and you will see the X I think and get an audible warning .... but it won't do the downshift until you are in the proper speed range. That is a pretty wide window and it is never an issue on-track.

If you are in too high of a gear for your speed it will downshift for you but that is also a very wide window and quite obvious. This is like you are in 5th on a cool down and then roll into the pits at 10 MPH stuff. Not because you are in 4th at T-1 and really should be in 2nd or 3rd. It won't down shift in that situation because the engine isn't lugging. In fact you can drive the full track at VIR in 4th and it won't shift on it's own.

No issues with temps other than the engine oil gets close to 290 when it is hot and if you run high RPM's . We have Z51 cars and this is the 2nd with the A6. We have also had 4 C6's with the MN6, no issues there either. All of them are stock but probably not being driven as hard as yours. I don't drive the Corvettes any more ... got my SRF now.

V8 Juice

I agree with the above well written description of the paddle shift. I run a C6 with the paddles at Putnam Park, VIR, CMP, just back from VERY HOT Road Atlanta and have no problems with shifting if downshifts are done at end of braking. Upshifts are a minuscule fraction slow, but you never miss a gear and are never distracted by focusing on heel and toe. Had temp problems with prior C5 auto, but not on C6, most likely because can run in most efficient gear, even a few yards in 5th on the long runs at VIR and RA just before braking zone cool engine and trans with minimal time loss. Very easy to get back to 3rd gear while negotiating the zig zag corners - try that on a standard! The only gripe - the manual rear end isn't available on the paddle shift and you loose some oomph out of the corner, even in 2nd gear. This is where the Z06s will pull away from you.
The low 2.56 ratio just doesn't allow the revs to stay high. I am at best an intermediate driver and a very good driver may run better times in the manual, even with comparable rear end ratio.

kenw

I ran at VIR at the PDS put on by the Museum. My 06/A6 has the APS Twin-Turbo and 315 gears. The car did really well on the track. I had to be carefull with the power of the twins but once I had a few laps it felt good. The trans worked well although there were a few times it did not shift when I wanted. Not sure why the trans temp never got to high but my engine oil temp got to 270 by the end of each session. One time my traction control came on at 115 mph when I was passing another car. That was cool.

ScottJ03

I think it goes into a type of Safe Mode when temps are hot. Changed driving style helped..

V8 Juice

"The trans worked well although there were a few times it did not shift when I wanted" - Were you running with paddle activated and trans wouldn't accept shift? Did you get an "X" in HUD? I've never had a paddle shift refused unless I made stupid move like downshifting while high revving.

"engine oil temp got to 270" - that's good #, I went to 310 last weekend at Road Atlanta where it seemed ambiant was also 310. I was also at NCM VIR and finished with temps around 290.

"the trans temp never got to high" - I find that if you can run just a few yards at the end of the long stretchs in 5th, i.e. right after Oak Tree at crest of hill at VIR, it makes a big difference in trans and engine temps and doesn't hurt lap time much. It is so easy to downshift with paddles that you can get back to 3rd or 2nd quickly even while in zig zag corners.

I looked into changing rear axle ratio and thought it wouldn't work with C6A6, but you did.....how is it working, any problems? Would love to have higher ratio.

kenw

V8 juice---Yes I did get an X a couple of times.

I did start shifting into 5 on the straights and it helped keep the temps down I think. Mostly used 3 and 4 gear using 2nd was to hard to control.

I believe the 315s are the perfect gear set with the A6.

I have been very happy with the whole car overall and really impressed with the twin-turbos.

george J

Well I took it out this weekend and found a repeatable pattern (and solution). I was trying to paddle shift up (3rd to 4th) at 6K rpm on the front straight, but by the time the program kicked in the car was at 6500 rpm redline and so it balked. Initiating the change at 5500 rpm fixed that.

Which raises a question I asked a couple of months ago -- is the 2008 shift paddle improvement (1/2 the delay according to Road & Track) an available (s/w) upgrade? I asked my dealer today and they said no, but what do they know!

AU N EGL

Brakes slow you down, not the transmission. So brake hard first to slow, then down shift just the moment prior to turn in.


Besides replacing transmissions is very expensive

Dirty Howie

Better get a tranny cooler....270 will kill it....did that twice

I have a huge cooler in front of my radiator and run it straight to the tranny, not thru the radiator TOC. My tranny temp on a 110* day was 220.

I know I have a C5 A4 but your tranny temp is too high !!!!


DH

V8 Juice

[QUOTE=Dirty Howie;1562200121]Better get a tranny cooler....270 will kill it....did that twice

I believe the 270 temp quoted was oil temp that is high, but shouldn't be a problem. I agree 270 degrees is asking for trouble in auto transmission. My C5 auto was ill- suited for track - poor gear selections and too long in 3rd at tracks like CMP would overheat.