A4 B7 Multitronic strange intermittent problem

[Desmond0313]

I have a 2005 A4 B7 2.0 TDI (BLB motor code) with the multitronic tranny. I bought the car from my uncle a little less than a year ago. The car is on its second gearbox, which was bought used, with 70 000 km (43 500 mi), but he couldn't tell me when that was, since he kept no service record at all (he completely neglected the car, always took it to shady mechanics who did everything the cheapest...), so I cannot tell the exact mileage of the gearbox. The issue I'm having has been present ever since I bought the car: sometimes the gearbox behaves very sensitive to the throttle pedal, which means that even with very modest acceleration it just keeps the revs at 2000-2100 RPM constantly, and only starts putting a higher ratio if I just barely touch the gas pedal. It feels like the gearbox thinks I want to accelerate hard so it doesn't put a higher ratio. Now in the title I mentioned that it's intermittent. What I mean by this, is I start the car, get going, it acts as described above. Then I stop when I reach my destination and shut off the car. When I get back and restart the car again, the problem disappears, it works very nicely and puts ratios how it should. So when the problem occurs, restarting the car solves the issue. At first I thought this was some kind of "warm-up" mode when the gearbox is cold, because I know some automatic gearboxes have that, and it only seems to do this when the car is not warmed up yet (but it doesn't do it on every cold start, so that's why I think this is not the case). Gearbox ECU was repaired last week, because I was getting random switching to Sport mode all by itself, then the PRNDS flash. All the contacts in the ECU were re-soldered, and all those problems have disappeared, but the above described problem didn't, so I think the problem is not the gearbox ECU.

Another thing that turned up during the removal of the gearbox ECU, is that some previous idiot mechanic put regular ATF in the transmission instead of CVT oil (the oil that came out of the gearbox was red, there is no red CVT oil in existence). The gearbox was refilled with CVT oil, but since you cannot drain all of the oil from the gearbox, a good 2 liters of regular ATF is still in there, that's why I'm going back for another oil change, probably next week. That may finally get rid of all the red ATF in the 'box.

I mentioned this in case it can be related to the problem, but to me, it seems like it's some kind of electronic/sensor issue.

Any help would be greatly appreciated. :)

[Okedokey]

You can change the oil yourself. Also change the inline filter. Sounds like a flush is in order. Also try changing the relays under the ECU plenum, as they can cause CVT issues where the signal is intermittently lost. I'd suggest under the circumstances that you do a full maintenance regime, change all fluids (power steering, collant, oil, etc).