Tiptronic - engaging D or R at cold start

[Filipão]

Knowledgeable Sirs,

On my S4 Avant - when cold starting - I must wait 20 seconds till rpm drop to "normal" to engage D or R, otherwise it jolts.

Any thoughts on this?

Thank you thank you.

 

[Daggerit]

Knowledgeable Sirs,

On my S4 Avant - when cold starting - I must wait 20 seconds till rpm drop to "normal" to engage D or R, otherwise it jolts.

Any thoughts on this?

Thank you thank you.

I’ll see what mine does next time but I don’t think it jolts too much. I imagine it’ll just be because it’s at increased revs, like releasing a clutch at 700 rpm versus 1500, it’s always going to have a more noticeable effect.


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[Filipão]

I’ll see what mine does next time but I don’t think it jolts too much. I imagine it’ll just be because it’s at increased revs, like releasing a clutch at 700 rpm versus 1500, it’s always going to have a more noticeable effect.

Indeed not too much, but noticeable enough to annoy my tech mind... Thank you!

 

[cuke2u]

With a cold engine the oil within the torque converter will also be cold, thus thicker as well...

 

[Daggerit]

With a cold engine the oil within the torque converter will also be cold, thus thicker as well...

Definitely a fair point!


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[Terminator x]

Same with me although I get round it by releasing handbrake then selecting D.

TX.

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[Filipão]

Same with me although I get round it by releasing handbrake then selecting D.

TX.

Thank you. I tried it, but to select any gear I must press the brake pedal.

 

[Daggerit]

Thank you. I tried it, but to select any gear I must press the brake pedal.

You also have to be pressing the brake pedal to release the handbrake though?


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[Terminator x]

Thank you. I tried it, but to select any gear I must press the brake pedal.

Yep foot on brake, release handbrake, select gear, release footbrake, drive off. No clunking.

TX.

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[Filipão]

You also have to be pressing the brake pedal to release the handbrake though?

Indeed, but you can do it in any gear lever's position.

 

[Filipão]

Yep foot on brake, release handbrake, select gear, release footbrake, drive off. No clunking.

TX.

Even with idling at 1200rpm?

 

[cuke2u]

That sounds a bit high, do other S4 owners experience it this time of year? Mine only revs just over 1000rpm then drops very quickly...

 

[Daggerit]

Even with idling at 1200rpm?

That’s actually what I do come to think of it.


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[Daggerit]

That sounds a bit high, do other S4 owners experience it this time of year? Mine only revs just over 1000rpm then drops very quickly...

Can’t actually remember where it sits in the S4 to be honest, didn’t think it was that high but could be!


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[Filipão]

Can’t actually remember where it sits in the S4 to be honest, didn’t think it was that high but could be!

Yes - I may be exaggerating a bit. Will need to confirm. Sorry

 

[Terminator x]

Even with idling at 1200rpm?

Yep did I just now driving back to the house. Straight from engine start works fine.

TX.

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[Filipão]

Yep did I just now driving back to the house. Straight from engine start works fine.

TX.

Thank you so much TX, will try it out tomorrow morning!

 

[Filipão]

I do confirm idling at cold start to be 1200rpm (S4)

 

[Filipão]

No matter how I deal with it, using either electric hand brake or foot, at these high rpm the jolt is always felt.

So, the only solution I have found is to allow idle to drop to normal levels and select.

Meaning I wait, exhaust sounding like a tuned Honda, everybody looks at me as if I am a noisy teenager, I blush, revs drop, people don't stare anymore and I drive off.

Torque converter oil ice cold or not, engaging is still smooth (regular idle rpm).

Hope to get many other opinions on why the muffler's valves are open at cold start and why revs are so high. Does it make technically any sense?

Thank you all!

 

[Terminator x]

Ha ha seriously mine jolts if just selecting gear upon startup but doesn't if I take the handbrake off first.

TX.

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[SMI77]

Yep foot on brake, release handbrake, select gear, release footbrake, drive off. No clunking.

+1

exhaust sounding like a tuned Honda,

My my, you do have a problem. ;-)
It would appear that at cold start, under acceleration and heavy throttle application are the main criteria for all 4 tips to operate, otherwise quiet driving is 1 tip only.

With a cold engine the oil within the torque converter will also be cold, thus thicker as well...

I take it this may well be a synthetic oil, so would it necessarily be significantly thicker?

 

[Filipão]

@SMI77 - yes I do have a problem, I'm too freaking old! He he he!

@terminator x + @SMI77 - There's something I am definitely missing here.

Symptoms must be the same (if not worse) if foot brake on (on 4 wheels) , as well as with electric hand brake on (on, only rears)

So either way there won't be any room for absorbing the jolt I am noticing.

 

[cuke2u]

+1

My my, you do have a problem. ;-)
It would appear that at cold start, under acceleration and heavy throttle application are the main criteria for all 4 tips to operate, otherwise quiet driving is 1 tip only.

I take it this may well be a synthetic oil, so would it necessarily be significantly thicker?

Its a sealed for life, according to the beemer forums, thus difficult to find what oil it actually is, bmw recommendations seem to difer from zf, who don't.
Info from here https://f10.5post.com/forums/showthread.php?t=1228391
But automatic tranmission (ATF) it is, possibly ATF lll or even Lifeguard 8, but mineral based not synthetic according to here
https://www.opieoils.co.uk/pv-205365-zf-lifeguard-8-atf-automatic-transmission-fluid.aspx
Having said that I have just read that ATF can come in synthetic form as well https://en.wikipedia.org/wiki/Automatic_transmission_fluid