Manual Mode Engine Pulsing

[Lava]

I used the manual transmission mode today for the first time on my new (to me) 2017 XLT. Was going down a steep mountain highway and shifted all the way down to 3rd, which put me at about 2700 RPMs. Worked great and was nice and smooth at first but after awhile it felt like the engine started to "pulse" for lack of better word. I shifted into 4th and it continued to do it. I shifted back to D and then back into M to see if it would reset and operate smoothly again, but no dice. What is happening? Is this normal or something I need to get fixed?

 

[07xln]

When I had my 17 Limited it would do something similar to that. We took a vacation to Branson one year and lots up big steep hills around there and I would put it in manual and pick a lower gear for it to not upshift past. I would get the weird surging effect at times too. It was very odd. Never figured out why it was doing that.

I realize Im of no help but I did have the same experience with mine

 

[Lava]

Did you ever have any mechanical issues because of it? Trying to figure out if it's expected behavior or if it's a symptom of something wearing out.

 

[justinp16ex]

Did you ever have any mechanical issues because of it? Trying to figure out if it's expected behavior or if it's a symptom of something wearing out.

How was the trans temp?

 

[Langer]

I have used manual mode through the mountains of TN a lot, and have never had this. Did you have cruise control on?

 

[Lava]

Trans temp was only 104F. I would have expected it to be much hotter even on the flat. Cruise control was not on.

 

[Langer]

Trans temp was only 104F. I would have expected it to be much hotter even on the flat. Cruise control was not on.

That trans temp seems unnaturally low for driving. Maybe that’s a thread you should pull?

 

[Lava]

What are your typical flat ground trans temps?

 

[Langer]

@Lava This evening in 41 degree exterior temperature, I drove 2 miles to the gas station, with cruise control set at 45, and my trans temp got up to 112 F. Haven’t had anything that’s required me to get up to highway speed for an extended period of time. When I do, I’ll update.

 

[Grover6]

My '16 does that as well when the transmission is cold. Once it warms up it stops. I assume it is the torque converter not liking cold oil.

 

[Langer]

@Lava After driving about 35 minutes on flat interstate at 75 mph in 39 F external temp, my trans temp is 199 F.

 

[Lava]

My '16 does that as well when the transmission is cold. Once it warms up it stops. I assume it is the torque converter not liking cold oil.

That's an interesting observation - I've induced it three times now and two of the times were soon after starting up with a cold engine in the mountains in winter. The third time the trans temp was 176F after ~30 min of operation, so that one doesn't fit the theory. Although I was still in the mountains in winter.