Hello, sorry it has been a little bit since I’ve been on here I’ve been super busy. I parked the S4 about 2 weeks ago and bought something else to drive for now.
This last summer I noticed the car making its rumble/shudder while driving some Mountain Roads. I had to keep turning the music down and paying attention to the road to see if it was caused by imperfections and the road surface. I thought it was all in my head and it was the roots from the trees growing under the road making the car Rumble. Fast forward until recently, yes when it got cold, the car started doing the RPM bob up and down. After doing a lot of reading, people say this is pretty normal and that it’s the torque converter causing the RPMs to bob up and down. I read a couple places about the torque converter seals going bad and this can cause that. Recently though, the car has exhibited acceleration issues when under light-to-medium throttle. It’s almost as if the car Miss steps as it’s accelerating. If i jam on the throttle it goes away completely. If you drive around like a maniac everywhere, the car drives absolutely fine. I plugged in my laptop and booted up vcds and did some logging. I’m not an expert doing any of that, I don’t know my way around vcds extremely well, but every time the car did it thing, I hit the mark button. Looking at the data, each time I hit the mark button, there seemed to be little bit of slip in the torque converter. When the RPMs bob up and down, when they get to the lower portion of the RPMs, there is a mechanical sound that I have a hard time describing. I apologize if I’m repeating anything I already posted, just trying to remember how the car drives off the top of my head as I haven’t driven it for a week or so.
After driving around with the transmission like this, I figured the first thing I should try would be a fluid and filter swap. It did absolutely nothing to help with the issues I’m experiencing. I checked and double-checked and made sure that the transmission fluid level is right. I took a level to the transmission pan and make sure the car was level and I made sure that I watched the transmission temperature and vcds and that I follow the step-by-step instructions in the service manual and from other DIYs I found. This isn’t the first automatic ZF transmission I have worked on, so I have done this procedure a few times with other cars as well. After driving around for a couple hundred miles, I double checked the fluid level to make sure the fluid level was correct.
I wish there was a way to do a more detailed diagnosis of the problem. The problem I’m having is I don’t have any DTC or stored codes to go off of. I have already started saving up for the inevitable. I’m either going to go one of two routes. 6MT swap or I’m going to buy a new torque converter and a rebuild kit from ZF and tackle my first automatic rebuild.
Thoughts?
