gbove

Hi -- I have a 99.? A4 Quttro Avant, 2.8 30V, 100K miles. (Also have a 1998 identical vehicle, courtesy a drunken texter...) Although usually perfect, the transmission will clunk at random times, usually in 5th at 40-50 mph, and sometimes the gear indicator lights on the dash will all light red. When this happens the car loses shifting ability, and will not shift in manual mode either. And then from a start, it has no power, like it is go-cart with a bad centripetal clutch. Turning the car off and back on usually resets whatever happened. There are no related codes. Because of this I just replaced the transmission fluid and filter, thought this might fix the problem (and it should have been done years ago from the looks of the fluid). But it did not. I could not find a related post. Ideas? (Other than replacing it with the one from the 1998?) Thanks in advance.

gbove

More information --- I have found the term "limp mode" in regards to the transmission, and that there are lots of causes for that, including air flow issues. Before all this I was getting codes for the O2 sensors (although they look fine when monitoring with VAG-COM(. The car was never used hard before we got it --- I found the air intake basket (before the filter) full of junk, and cleaned that and installed a KN filter. Cleaned the MAF sensor, no codes on that, but why not. Tried to clean the throttle body, did spray the sensor, but did not get the throttle body off to clean. The vacuum tubes in that area were all brittle and I replaced them. Since this and the tranny fluid replacement we have only driven 30-40 miles. No codes have come up so far, but the clunking and limp mode have happened again.

GTA_Driver

Is there any play of the driveshaft?

gbove

No play in the driveshaft; this only occurs once every few days, very randomly, but always while at a constant speed.

Geoffrey Bove

No play in the driveshaft; this only occurs once every few days, very randomly, but always while at a constant speed.

Geoffrey Bove

OK, now it threw some codes at me:

16795 - Secondary Air Injection System
P0411 - 35-10 - Incorrect Flow Detected - Intermittent
16806 - Main Catalyst; Bank 1
P0422 - 35-00 - Efficiency Below Threshold
16816 - Main Catalyst; Bank 2
P0432 - 35-00 - Efficiency Below Threshold
16487 - Mass Air Flow Sensor (G70)
P0103 - 35-10 - Signal too High - Intermittent
18032 - MIL Request Signal Active (Check TCM for errors too!)
P1624 - 35-10 - - Intermittent
17549 - Load Calculation Cross Check
P1141 - 35-00 - Implausible Value
17535 - Fuel Trim; Bank 1 (Mult)
P1127 - 35-10 - System too Rich - Intermittent
17537 - Fuel Trim; Bank 2 (Mult)
P1129 - 35-10 - System too Rich - Intermittent

As I said, I just cleaned the MAF --- could the KN be doing this?

GTA_Driver

Ah, you shouldn't have touched the MAF.

In any case, how are your engine mounts? Someone had a clunk from differential mount as well.

Geoffrey Bove

Thanks GTA --- the air flow codes were there from the beginning, although not so many (see second of my initial posts). Everything said "clean MAF." Now I will do it again and replace the K&N as well, I think it threw some oil in the mix. The symptoms are not consistent with engine mounts, it is far more irregular, duration is variable, and sometimes there are multiple shimmies. I would do the sound if this was CarTalk but cannot ---- it more feels like the tranny is going to simply fail, like it goes out of and then back into gear. As one other person on this Forum said, feels like the next sound is going to be that of the tranny falling off the car and onto the road!

dirtracerny1

Sounds like your Tranny is in safe mode, i bought my 98 A4 in December and it was in safe mode, the guy told me that one of the tranny mounts need to be changed, come to find out it was locked out. when i have the car in auto mode i.e. "D" it goes into safe mode, if i over ride in tip mode its fine but i have a recognition switch error code come up and tranny goes back into safe mode. I changed out the tiptronic shift board and the tcm and nothing fixed it.