2015 bucking HARD under slow acceleration in 1st/2nd gear.

saucer

Veteran Member
Joined
Jun 4, 2010
Location
Fayetteville, AR
TDI
2015 Passat SE
After a month of diagnosis, I've noticed the hard bucking really only occurs under heavier acceleration/uphill. Lesser bucking has now even occured in 6th gear on the interstate, in spurts of two or three. But when she's under load, it bucks hard, like I'm hitting the brakes.

I've driven plenty in Manual mode to rule-out the DSG; this happens independent of shifting.

Here's the most reliable evidence: this seems to be happening at a specific temperature and only at that specific temperature, which - if my normal coolant temp is 190 - seems to be around 180. It will not happen as my car warms up toward 190 and will not happen AT 190, once I've been driving for a bit, ONLY in that window of either driving for the first time in several hours or after letting the car sit for 5 minutes or more. In fact, a couple of times after idling or sitting a store for a few minutes, it will die on me as I try to drive away. And... once it's happened as the car warms up / warms back up, it will not happen again as long as I'm driving.

What could this be? EGR? HPFP? MAF?

110k miles, no mods. CVCA. DSG.

I've scanned with VCDS but am getting nothing but a code for my radio and backup camera.

Thanks for any help, guys!
 
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saucer

Veteran Member
Joined
Jun 4, 2010
Location
Fayetteville, AR
TDI
2015 Passat SE
If anyone ever winds up here via search, it turned out to be a bad lift pump sensor. Dealership replaced it under warranty, but it looks like it was an hour of labor and a $35 part.
 
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