Hi!
This is my first post at forum .
I have a 2003 Z4 3.0i M54 roadster .
I bought my car last year in August and it was at 92.000kms with no problems.
In winter my car started to make a thud in second gear ; very strong thud and rpm drop .
(You can see it on a video , car is shaken at 3000rpms !
If the engine/tranny/fluids etc. are cold this happens at 2nd gear at 3000rpm .
As the engine/tranny/fluids get warm up there is no thud at 2nd gear but there is always a rpm drop !
When engine/tranny/fluids are at normal operating temperature there is a rpm drop at 5th gear ; at 5th when you kicked the gas pedal a little it goes to 3000rpm and drops 250rpm . Sometimes it makes at 2750rpm .
While lowering the gear from 5th to 4th there is a drop ( can't hold the rpms stable , and falls back 250rpm)
There is no problem at kick down or no problem with 0-to xxkm acceleration.
When I first experienced this I changed ignition coils and spark plugs ; btw there is no error code !
Changing these parts did not help .
I flushed the ATF but no luck
Actually I think this is related with torque converter ; I guess a worn lock up clutch ?
I uploaded some videos .
Videos about ;
When the engine is cold a thud at 3000rpms at 2nd gear ,
When engine/tranny/fluids are at normal operating temperature there is no thud at 2nd gear (a night video)
When engine/tranny/fluids are at normal operating temperature at 5th gear ( please ignore the temperature gauge because my thermostate was broken)
And normal 0 to ... kms acceleration videos
I don't want to change my TC for now because I don't use my BMW so much ; I drive it on weekends and in holidays.
I consider to use Dr. Tranny Instant Shudder Fixx ; I bought from amazon ; customer reviews are positive.
Thanks in advance