2016 LR4 with 74,000 miles. Experienced a significant shudder, thud, clank on several occasions while driving uphill on Oregon coast at around 55 MPH yesterday. Gentle throttle. Not driving aggressively. Always occurred when transmission (in automatic drive mode) was downshifting during uphill ascent. Car hesitates, then shudders rather violently once or twice then continues to operate normally. It's a significant and startling noise and feel. Can't determine source of noise (front or rear) as it happens very fast. Very jarring. Feels like car was slammed into park for a split second.

Occurred at around 5 MPH in parking lot about an hour later. Proceeded to drive a couple of hundreds miles home to Idaho in manual shift mode later the same day. Only occurred once in manual shift mode and that occurred in 5th gear at about 50 MPH during slight ascent and gently acceleration.

Recently drove across the country and rocky mountains and from northern Idaho to coast of Oregon with zero issues.

What are your thoughts on....

Being caused by improper transmission fluid level? No signs of leaks.

Dr. Tranny Shudder Fix? If yes, is fill near catalytic converter?

Transmission fluid drain and flush?

Reset adaptive transmission settings with Gap IID tool or iLand tool from Atlantic British

MAF issue?

Vacuum issue?

Drive shaft issue?

Transfer case issue?

Thanks in advance for your thoughts.

 

any dash warning messages?

 

Thanks for the reply. No warnings. Just read a similar account from someone who said it turned out to be spark plugs. But the loud and rather violent jerk or shudder makes me think something more serious like the torque converter.