I will go ahead and first apologize for this long post, but looking for some ideas/suggestions from the collective super minds on the board.
To get some useful information back, I think it is important to provide enough detail, and some history.
History:
The RS6 had been garaged for about 3 to 4 weeks; it started up fine. Took it for about 20 minute city drive and parked it again. Decided that I need to take another drive, and the car would not start. It would crank up, but not fire up. Turning the key I would see the battery registering above 12V (center line), and during start attempt dip to 8. At this stage I figured I'd leave it alone, order a new battery and spark plugs.
Next morning I take the keys to the garage anyway, and start up the RS6. It starts up just fine. Take it to work. Go pick up lunch, which is about a 5 minute (3 mile) ride. When I get back to the RS6, it won't start again. Same as before. I call a friend, I hook up the battery cables, and car starts. I figured I have it figured out, and a new battery is needed.
I get the battery and spark plugs, and I changed them over the weekend. I also did the the RS6 Sportec lower air vent mod.
After all this work is done, I have not had any issues starting the car up, and has been at least 1+ week since. Took the car to work. Took the car on short drives. Stop and restarts no issues. I figured I was done.
At this stage I am still running on a tank of gas that was in place even while the car was parked. No new gas has been added.
Issue:
After car has been strong for a few days, on my way home from work, after about a 15 minutes (possibly 5-7 miles of city driving), the car jerks a bit.
Continues to drive no issues for another 2 minutes and it jerks about another mile or so down the road. Afterwards no issues for about 15 or so minutes. I think I might have gone about 7 miles or so. Lights are horrible during my drive. I feel another jerk, and this time a bit stronger than the last one.
Keep in mind that the jerk was no associated with any downshift or upshift. I could have been going anywhere from 15 MPH to 40 MPH at each of the occurrences. The jerk itself felt more like the engine chocking, and not a tranny issue.
I pull to a parking lot, take out my Mobile VagCom, plugged it in and connected with my iPhone. No tranny DCTs found. I feel good. However there were engine DCTs as shown further below.
I am thinking at this point I either have some possible bad gas, or something else is messed up, such as my spark plug installation. Or even bad spark plug.
One other point to make is when I felt the first jerk, I was accelerating slowly behind a couple of other vehicles, and with the windows opened, I heard what it sounded like air being rushed through a small opening. I had not noticed this before, but it could be me. Also unsure what level of sound difference the lower air vent mod contributes.
I save the codes and clear them. Take it to the highway for a 5 minute drive from work to home.
All working just fine, and no issues. As I am about to take the exit, all bells and lights in the dashboard go off, the last I saw was the oil icon large in the center dash, and car shuts down. Given my momentum, I am able to exit the highway and enter a parking lot. Damn the steering is heavy, but made it.
Park the car, check for leaks and nothing. Spent 5 minutes around the car. Turn it back on, and it starts just fine. Check the DCTs, and the same ones appear.
Get home fine as I am about 2 miles or so away. No more issues, jerking or shutting down.
I check the whole car again, and various modules on the car.
I go online and research the codes. Main concerns appear to be a leak, which is interesting enough based on the sounds I had original heard before. So I get a few details to log, sector 115 (the boost), and MAF readings
So now I grow a pair, and about 15 minutes go after all the checking and rechecking. I load the wife up in the car, she is in charge of the computer logging with the VAG tool, and also checking to hear anything.
We end up going for a few runs, as there are a couple of choices around town to proceed with caution. Car is strong again. No more leaking sounds. No more jerking and chocking. No more DCTs after the last clear.
Needless to say, MAF readings appear to be quite healthy, idling at 5g/s, and on the top end reaching north of 250g/s.
The boost appears good. I am adding some excerpts below.
Engine Fault Codes:
5 Faults Found:
17535 - Fuel Trim; Bank 1 (Mult)
P1127 - 002 - System too Rich - Intermittent
17537 - Fuel Trim; Bank 2 (Mult)
P1129 - 002 - System too Rich - Intermittent
17544 - Fuel Trim: Bank 1 (Add)
P1136 - 001 - System too Lean - Intermittent
17546 - Fuel Trim: Bank 2 (Add)
P1138 - 001 - System too Lean - Intermittent
16705 - Engine Speed Sensor (G28)
P0321 - 008 - Implausible Signal
Questions:
1. One of the runs, I have an actual boost spec request at 24PSI, but the actual was 28PSI. Is this normal for our RS6? My car has stock ECU, and never been tuned. First boost graph ranges from 14PSI to 21PSI
2. The codes, that were generated based on the jerk/sputtering, any idea what it could be? Do I need new MAFs? Should I change the engine coolant temperature sensor and fuel regulator sensor? Could it be a leak somewhere that I've yet not found, but will be looking for.
Thanks for any help you can provide. Sorry for being long on the details.
Concerns on boost and misc
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