Flummox

Hi all. I'm the new owner of a 2016 A8 4.0T with 8.5K miles (CPO). Really, really love the car. After driving it for a couple of weeks -- mostly around town -- I have a couple of observations that I hope the collective wisdom here can shed some light on:

1. When slowing to a stop in traffic or in a parking space I notice an unexpected coarseness in the engine. Sometimes it's just a little shudder, but other times the engine surges a bit causing a slight lunge forward. This is particularly disconcerting when pulling into my garage, which is a tight fit for such a large car. It *seems* to be more noticeable when auto stop/start is engaged, but that might just be my imagination.
   
2. When I lift off the accelerator at around-town speeds, I feel a greater than expected deceleration. It feels like engine braking, which I expect when descending grades, but I feel this consistently, even on level terrain. I don't feel this sensation in my wife's 2016 Touareg. It also has an 8-speed automatic, but I admit I don't know if it's the same auto as in the A8.
   
3. On cool mornings (mid-30s) I'll use the seat heater. A couple of times (again, not consistently) it has felt as if the center third of the seat cushion is being cooled rather than being heated. It's a very odd sensation.

These are on a list of things to talk to the service department about when service time rolls around, but I thought I'd ask the smart folks here as well. Has anyone heard of or experienced any of these issues? They're all subtle enough that they could just be the imaginings of a mind that is hyper-focused on a new toy, but I really don't think so.

Thoughts?

LexusLSguy

Although I don't have the 4.0 engine I do notice a few things that are similar in my 14 CPO with the 3.0 engine

1 - I don't like the auto-stop / start feature and keep mine off. When the car re-starts it does kind of surge and since I don't spend much time in stop and go traffic the very minor improved fuel economy vs extra wear and tear on the starter is not something I prefer.

When I first got my car I noticed the idle seemed a little "rough" or rather I was feeling more vibrations then I expected. Not knowing what fuel the previous owner ran I used my favorite injector cleaner combined with 93 octane fuel. This did improve things and she is smoother at idle. DuraLube severe system cleaner has been my favorite for years and really only need to use half the bottle per tank. Walmart has it for about $11.

2 - I don't really notice the pronounced deceleration you are mentioning. It is a fairly heavy car and maybe you are describing something that is more accustomed the 4.0 engine I'm not sure. How are your tires tread and are they inflated properly? I'm pretty **** about this and keep a nice little 12v compressor in my trunk plus a good gauge. My dealer put on 4 new tires when I purchased the vehicle. They also could not get the pressure right. 36 one side, 41 on the other, etc. Don't forget to set your tire pressure on cold tires.

3 - I don't notice the cold air with the heated seats but the center does not heat up as much compared to the outside. I also can't take but the lowest setting. I will turn it on medium for a few min but then turn down to low because it is too much for my rear... lol

Psy Wagon

1 - In the owners manual it states when turning the car on it can be "rough" for a bit. But randomly getting course could be the start/stop function which I disabled.

2 - I do notice this at slow speeds occasionally. I always thought it was the transmission kicking down a gear to anticipate slowing down but not sure.

3 - Seat heater seems a bit weak compared to other cars imo.

Flummox

I'm not a big fan of auto stop/start either, but I'm trying to get used to it. For the time being, I've disabled it while I try to get a handle on this problem.

Interesting idea. I'll give it a shot, although with the low mileage I'd be surprised if there was significant gunk in the fuel injectors.

Pressure is spot-on. I just took care of that. TPMS is reset as well. I haven't checked the tread, but I will

Wonds

2. I think this sounds like engine braking but I only get this when going down steep hills. The car detects it's going faster than it should be for the amount of throttle applied and retards the power delivery. I've not tried it in a while but it may be linked to traction control, try turning it off and see if it still happens, could be a problem with a speed sensor or something.