Salhab

I own a 2004Sl 500, it runs great and everything is perfect on the highway, but once i am heading to the mountains and gasing it, at some point the tiptronic will die and the car will lose some power.
Took it to the dealer and did a star diagnosis, no faults were recorded or found. drove test it with the star plugged in, the tiptronic failed and the loss of power was felt
But no faults were recorded. Advice please!

vtvette

Can you please elaborate by "the tiptronic will die"? Do you mean the transmission is having issues?

Salhab

It will be stuck at D.
Wont be able to downshift or anything, just D. And when i kickdown the car will accelerate but not as fast
It shld

vtvette

I assume the dealer checked the transmission fluid level? When is the last time the transmission fluid and filter were serviced? How many miles on the car?

If the fluid level is good and has been serviced I would assume the valve body in the transmission may be having issues but, it is difficult to say without seeing the car in person.

Salhab

A month ago, they were serviced. The tricky part is that only this happens when am going uphills to the mountains. It never happens when am on the highway.

vtvette

You know what - I wonder if you don't have a failing Catalytic Converter. It would be most prevalent uphill in the mountains, and would restrict the engine of power which may prevent the transmission from shifting?

Salhab

Wont that show on the star diagnostics?? Will ask about it for sure. Hope it will be solved soon, cause its driving me nuts. I cant even pass another car sometimes!

vtvette

I don't think it would show on Star Diagnostic. There are no Exhaust Temp Sensors on your car so, Star has no way of knowing there is an issue.

The engine works hardest traveling up hills (especially mountain roads) so, this is where plugged or clogging cat's first show up.

I think it's definitely worth looking into.

Salhab

Thank you for the help. Will let u know how this goes!

Philip317

Hi Salhab

I know exactly how you feel as we have had the same problem. I have documented this problem and how I dealt with MB over a 7 year court case. MB know of this problem - has been known to them since 1996. Don't want to blow my own trumpet but you might consider my entry later in this series of emails. Staggering to see that MB have hidden this problem. Take care as this could prove fatal. The sticking in gear can happen when you ave a surge in acceleration such as moving fast from a stationery position or entering fast traffic on a motorway. Of all the times it can happen when you need the power.
Just be careful or simply get rid of this car as it could prove fatal.