Tiptronic box not engaging

[Jason Taylor]

I've noticed the past couple of times I've had the car out that when starting from cold and selecting D the box isn't engaging, if I put my foot on the accelerator the car revs as it would in N. After a few seconds the gear engages and all is well, no issues driving the car, changes up or down everything performs as it should. If I turn the car off and restart it it engages immediately. The only recent changes to the car was a tune but I can't see how that would affect the box?

Any ideas before I take it to my Indy?

Cheers

Jason

 

[deMort]

I would start with having the fluid lvl checked or if it has been years then change the tip oil and filter .

Unlikely but i assume the gear lever moves nice and freely and is not stiff at all ?

Fault code check of Every control unit .. it may show a fault or 2 which could indicate a problem ...

We do every control unit as there may be nothing in the Tip one but there may be communication issues with the tip cu in other units which leads towards a fault obviously .

 

[Jason Taylor]

Thanks democrat, hopefully it's just the oil level, I'll start there and get it checked out 👍🏼

 

[Jason Taylor]

I would start with having the fluid lvl checked or if it has been years then change the tip oil and filter .

Unlikely but i assume the gear lever moves nice and freely and is not stiff at all ?

Fault code check of Every control unit .. it may show a fault or 2 which could indicate a problem ...

We do every control unit as there may be nothing in the Tip one but there may be communication issues with the tip cu in other units which leads towards a fault obviously .

So, had the gearbox service and I still have fault, albeit intermittent, I think the next course of action is to put it back into the Indy and do the fault code checking exercise, anyone else experienced the same issue?

 

[gizlaroc]

So after the transmission was done it is not happening as often?


What year is your car?

Is this the Mercedes 722.6 transmission used in these?


It does sound like the levels are too low.

Also, what fluid did they use? Porsche changed it 3 times for this gearbox over the years, from MY06 I think it was they started to use a lightweight gear oil which should not be mixed with the stuff being used previously.


The reason I mention this is most people just drop out 4-5 litres which means you are mixing old with new, which is sort of OK, but not if you mix fluids.

I undo the oil cooler and pump the old stuff out and new stuff in, and keep doing it until you have new clear fluid coming out. That flushes the whole system.
Then I reset the adaptions.

However, I only ever reset the adaptions if ALL oil has been flushed, NEVER if only 4.5 litres has.


Anyway, drifting off a bit there, it still sounds to me very much like the level is slightly off. The oil needs to be 80ºc when getting the levels right, and only when it is 80ºc and dripping slowly from the fill plug is it right.
Considering these take around 9 litres in total (do on Mercs) it is amazing that 50ml out can cause so many issues like you are having.

Delayed engagement of Drive from a cold start is the first sign of level not being right.

Can you have a look at the connector? Undo it and see if any oil is showing inside?
Should be bone dry, if there is some sign of oil it might be leaking, very slowly but enough for the level to drop to the point where you get issues like yours.

 

[Jason Taylor]

Thanks for the advice

The car is a 2007 model

The goods listed on the invoice are, sump gasket, filter and atf plus transmission fluid

The car was due a gearbox service at 12 years old but this wasn't offered by the main dealer so wasn't carried out. The Indy did remark that the fluid taken from the gearbox was 'manky" meaning dirty I guess so it's probably due.
I have no mechanical experience so I'm afraid removing plugs etc is not my thing, I've used the Indy for years with various different cars and never had an issue, they are well respected so I guess I have to trust that they are doing the job correctly, the gearbox does perform perfectly otherwise.

 

[gizlaroc]

I don't doubt they are doing things right, but not many know that Porsche changed the fluid. But if your car was 2007 it will have used the later fluid and I 'presume' they will have used the same.

The problem is, most won't even know that you must not mix this later type with the earlier types.


Also, I have done loads of flushes on these 722.6 'boxes and have often had to go back and check the level again a few miles later. Delay engaging D for the first time or a change you feel is a good indication that the level is not quite right.



I would ask them if they can just double check the level again for you, say it is better but still doing it occasionally. Also, ask them if they looked at the electrical connector for any signs of leakage there.
The probably did and sure they won't mind you asking.

 

[Jason Taylor]

Thanks gizlaroc

That's good advice, I'll take it and give them a call tommorrow.

Jason

 

[berni29]

Hi

If the symptoms change with temperature then it's possible that the gearbox linkage might need adjusting on the basis it expands with heat and vice versa. I would also check any microswitches in the linkage.

Just my 5p's worth

Best of luck

Berni

 

[Jason Taylor]

Cheers guys

Cars going back to Indy tomorrow to have levels checked, although I've only said when put into drive the same has happened on occasion when also put into reverse so I do feel the levels will be the best shout but who knows, I'll have a better idea after tomorrow I hope.

 

[deMort]

Unfortunately after an oil / filter change and even though its made it better the next step would be a replacement of the valve body ..

You have in effect a restricted oil flow through a solenoid valve and whilst cleaning it all out would seem a fix in reality it's normally a valve body replacement next .

It is possible that continued driving and it will improve .. try that first for a few K miles and see how you get on .