I've been chasing an intermittent stutter/stalling issue for many weeks.

Although I say stuttering, it was rare for more than one "buck" to happen. Felt like someone ran into the back of the car or a flutter or fuel cut (not really a misfire). Seems related to cold and is most likely to happen on days that are cold -- below 45 degrees (F) -- and moist. If engine stalled on first start up of the day it would almost certainly stutter while driving once or twice or even die on me when coming to a stop.

Fuel pumps (both) and control module and filter have been replaced at a reputable independent shop. Their VAG-COM showed no errors while chasing this but stuttering was happening intermittently until the fuel pumps were replaced. Since then I've had a couple stall outs but no stuttering. Occasionally it will start and die (on cold engine or 1st start of day).

Two days ago while coasting to decelerate uphill, a vehicle in front of me nearly stopped while turning (at the top of the hill) and I did not need to stop as I'd timed it pretty well. But as I turned, the car seemed to "forget" to downshift and simply died right there. Started back up, though.

Seems more common for stalling like this when I coast (so toggling between closed loop & open loop) and then feather the throttle -- same that used to cause stuttering.

Last night (cold and rainy) coasting in 5th gear (auto transmission) in "D" on the selector, I found a dead spot on the accelerator. I pushed and the RPMs did not react.

I pumped the accelerator several times. Wheels did not spin but then ESP light came on and the dash display stopped showing me what gear I was in. All gears disappeared from the lower portion of the display. The engine then felt like a motor scooter that would wind up and have very little power. Felt like it was stuck in 3rd gear. Is that the infamous LIMP mode? I never read about it changing the display.

Once I parked and pulled error codes from the ECU I found a current fault (P0600: Serial Communication Link) and a pending fault (U0101: Unknown code). The pending fault disappeared from ECU once engine was turned off. P0600 remains which I interpret to be a failure between the ECU and the TCM.

With the engine restarted I could drive normally again and the display showed me the gears. I am logging with Torque Pro and ELM327. I know it's limited.

I have read that a bad MAF can trip the ESP but what about simultaneously tripping the P0600 or killing the serial connection??

 

Hi, i have exactly the same thing, the car while moving lost power and the glow plug light came on and flashed .. i re started the car and it cleared. The same think happened a few hundred miles later and the same happened.. Then i connected a computer and get p0600 error in the history but no current issues....... sounds similar to yours, did you get to the bottom of it?

 

The fuel pump needed an adaptation performed. That helped tremendously (no more stalling out).

The bucking issue (eventually) boiled down to a pinhole leak in the PCV hose plus a poorly performing Wastegate actuator valve. The valve was replaced after it (FINALLY) showed some electrical fault that was recognizable -- out of spec by ohms. The bucking has completely disappeared.

I do have a CEL that still comes on occasionally. Torque and ELM show low fuel delivery on bank 1. But my highway run just last week gave 34-35 mpg so I cannot complain about that. I don't recommend using Torque and ELM. I'm just telling you my experience (er lack thereof).

My hunch is there is nothing to "fix" yet -- just as when the actuator wasn't bad enough to recognize.