Need Help and advise automatic 05 S4 not shifting when its cold.

[COAudiS4]

Hello:

I have a 05 b6 s4 automatic. About a week ago I had to take my car in because I had snap the alternation belt while driving. Belt was replaced all tensioners where check and in working order and a new battery was installed. After the repair, It drove great even got back some the "down on power" I was getting. last week one morning the temperature had dropped below freezing, and was still cold in the morning (right above freezing) I start the car up no problem, car was cold but no real concern. Gave the car a few mins to circulate the fluids put it in reverse and then start to go.

Here is the problem when in drive normal (not S or tiptronic mode) I notice the car would not shift into second gear, I let my foot off the gas and pressed the gas again and it took a few seconds to respond. pulled over, placed it in park gave it an minute, put it in drive and start off again same thing. if I put in triptronic mode i could manually change the gears from first to second and beyond with no problems. Once the temp gauge on the car read half way I put it back in to normal mode and It would automatically change gears as normal. thinking it was a fluke, the very next day again the temperature was low, did all the same things above, but once the temp was at half way it was fine. (does not happen if the car is warm or hot after letting it sit or if the day is warm). So I took it back to the shop to have it looked at, on the way there it did it agiain, but since it warmed up by the time I go to the shop the problem could not be reproduced. And they said that the belt looked fine, I had asked if they could check the tranny fluid but was told it is a for life fluid and should not drop, but if I wanted they could, but there is a whole process involved.

So I ask you the forum, has any of you had this problem or know what is going on, or how to fix it?

thanks

[COAudiS4]

Hard to believe nearly a hundard people have viewed this post and yet no comments, suggestions, advice, not a single post.

Interesting, no one has had this problem?

[KAL]

I can chime in although I different platform but I thing we share some parts here. In my c6 4.2 with the ZF 6 spd I have an rpm fluctuation thing going on when the car is cold. Only happens when I maintain speed, under load it doesn't happen. And then when it gets warm its back to normal. I read around here and found a b7 S4 with a similar problem as mine and it turned out to be his torque converter. It was replaced under warranty for him and he was good to go.

Not sure if the problems are related but thought it might get you started. Also from what I understand its a good idea to change the fluid on these ZF trans after the first 100k miles. My source got it straight from the Trans manufacturer. Let me know how you get on!

[COAudiS4]

thanks for your input, I too was doing some research and I was thinking it of could of been the tranny seloids, but was told by an audi tech that it would throw codes, and I have not had nor where there any codes when they replaced the batteryand belt . so then I thought it might be the tranny fluid being low. the car is 99300. nowthe problem happens sporatically all the time but still no codes and the onboard check comes back "OK". if it is the tranny fluid needing to be changed, does someone know where at can get ZF automatic transmission fluid life guard 8 S67109031201 for less than $35 a quart? as the stealership wants $58.17 a quart.

Cheers

[COAudiS4]

Hey Y'all:

Ok an update on the problem. it turned out to be a brake switch on/off malfunction, there was codes in both the engine and the transmission. had a mechcanic diagnose the problem comfirmed the brake switch problem, change it out and erase the codes. problem fix, about a $100 fix 37 for the part the rest labor, hope this helps