Kinda a newbie here I have been here just looking at old posts for a couple of years but now I have hit a road block. 2006 A4 cabriolet has 139K miles changed the timing belt plugs and coil packs, Cleaned the MAF, Changed O2 sensors car runs great until you put it in gear and its under a load then it vibrates, Im thinking that it might be the snub mount. My son thinks that its stuck in limp mode ( he is a very good Mech. ) although we just cant figure out why we are getting this vibration. Are we missing something obvious ?

 

Is it a Quattro? Any chance the vibration is coming from the drive shaft? Is the vibration only show under load at a certain speed?

 

No its only front wheel drive, and it seem to get worse over time. but now its when the engine is over 3XXX rpm

 

Would be better if you mentioned driveability of the transmission as well. Is it driving fine? Since it's a fwd then it has a CVT transmission and isn't the traditional gear driven. If everything is copacetic as in no sudden jerking, hesitations, or shuddering I would take a look at the transmission mount and yes, the snub mount. If the car was in limpmode you definitely would notice not being able to accelarate at the usual speed/power. If it was transmission related you would see your PRNDS on your dash blocked out and flashing. Also you most likely wouldn't be able to drive at all.

The CVT should have periodic transmission flushes done by an reputable euroshop/transmission shop with the proper tools. Only Audi or Febi fluid brand should be used for this. There is a specific procedure to this and it's recommended that you do a transmission adaptation as well. The adaptations are done with a vagcom or Genuine VAG software. You can buy the prior for three hundred dollars from Ross-tech and do the flush and adaptation yourself if you're up to it. It's not difficult, just a little time consuming. Hope this helps.

 

It does drive OK with the exception of the vibration... No jerking or hesitations. Nothing flashing and no codes. Thanks for your insite and I will check trany mounts and snub. and get the fluid flushed in the trany