I have a 2015 Q7 TDi with 111,000 miles. It has always worked great. Lately I have noticed what feels like "slop" in the transmission. I do not drive it hard, and so it sticks in 3rd gear when cold. When driving with a light pedal at about 25mph, letting suddenly off the pedal can cause it to jerk. It also sometimes will jerk downshifting from 3rd to 2nd. This is getting progressively more common in the last 5,000 miles. I have had the transmission oil changed and the external drivetrain checked 1,000 miles ago. I have read that the transmission shifts can be related to plugged emissions equipment. Ideas? Thanks.

 

You can certainly do a throttle pedal and transmission memory reset/adaptation/relearning on it, which may help tremendously if that hasn't been done prior when the transmission was serviced. If it was reset, then there's a relearning period during which shifting can be notchy and significantly less refined in transitions, but usually the transmission shop takes it out for this drive if they reset it. If you didn't go to a transmission shop, then...???

Suggest you also review the Aisin OC8 transmission matching your Q7 TDI 3.0L engine (TR-81SD). Here's a reference link to specs and whatnot...please read through the info, as it includes the known symptoms/problems caused by the trans fluid not being serviced and/or overheating of the transmission, etc..

https://gearboxlist.com/aisin/tr-81sd/

 

If this one is running the settlement tune, I'd say that is a "feature" of the mapping. Mine would do it somewhat regularly. I have had no repeats in the six weeks or so after I remapped to a stock TCU tune... plus, the vehicle runs far smoother with more responsive shifts. I'm glad I made the change!

 

Gearbox oil and filter change was done at .. miles?

 

The transmission oil was changed at 102,036 miles. 7 quarts of Liquid Moly were added.

 

Like WES said, the TDI holding 3rd gear after cold-starting (when driving at modest speeds) until the car begins to warm up on the coolant temp gauge is absolutely 'normal' behavior for the dieselgate TCU tune...it's programmed to hold the lower gear / higher revs to speed the warming of the engine for peak efficiency/lowest emissions, etc. That behavior is 100% about Dieselgate and getting those emissions numbers down as quickly as possible.

FWIW: The 6 spd transmission on my '10 TDI does exactly the same after a cold-start...holds onto 3rd gear (speed limit is 30mph around town) until the car shows signs of warming up...usually after driving a few blocks like that it upshifts, or I can force it to upshift by activating the cruise control.

I'd definitely recommend you do the throttle pedal sensor calibration, as that takes literally 30 seconds to complete and no scan tool is required.

Another thing you should try out for comparison is simply moving the shifter into S mode (sport) rather than defaulting it to normal D mode. This simple change bypasses the negative (sloppy feeling) traits related to the Dieselgate TCU tune, although, once you calibrate the fly-by-wire throttle pedal the throttle pedal when in D mode may not feel nearly as laggy/disconnected as it currently does.

I usually drive my own TDI in the S mode on transmission around town as the shifts are so much crisper and this eliminates the lag you feel in D mode at takeoff from a standstill (stop light/turn lane, etc.), the hesitation between shifts, and also the problematic, automated upshifting preference at very modest speeds after the engine is warmed up, etc.

The S mode also introduces proactive downshifting with a bit of engine braking that the D mode no longer has on the Dieselgate TCU tune. This makes it fun to drive and safer because I'm not waiting on the transmission...it just goes immediately (like it should) and doesn't leave me stranded in a turn lane or wondering as to how it will respond when I need it to move quickly. Of course, the S mode will also favor holding a lower gear (speed and throttle input dependent), and so if I am out on longer errands or only driving modest speeds, then I'll either set the cruise control to keep me from speeding (this instantly allows the upshift), or just move the selector back up to the D mode, where the Dieselgate tuning upshifts 1-2 gears and drags the engine revs out of it's peak torque zone. As this Q7 has a learning transmission, the more time you spend driving it in the S mode or manual shift modes translates into it will feel and respond better when you are in D mode as well. This has been my experience. I don't drive harshly, but I'm not really a gentle driver unless the road conditions require it, so your mileage may vary.