How do you know if your transmission is about to fail?

Question
1

I’ve got a 2012 F-150 Ecoboost FX2 with 147k miles.

Lately, I’ve been having some acceleration issues at around 60mph. I saw a post suggesting that spark plugs and coils might be the fix, but my first thought was the transmission since I haven’t done any work on it before.

Either way, I’d like to stay on top of potential issues. Any advice? Thanks in advance!

2

Definitely check for any pending codes.

I had a similar issue with our '11. It would lurch or jerk while accelerating up a small mountain pass, and I was convinced it was the transmission because it felt a lot like how our old '04 Expedition acted when the transmission was going bad.

Turned out it was just misfires. A quick scan showed the misfire codes, and replacing the plugs fixed the problem.

3

My first sign was a check engine light with a misfire code. After changing the plugs and the coil boots, the issue went away. It seems like the plugs on these Ecoboost engines need to be replaced more often than other cars I’ve owned.

4

@Uma
Good to know. I’m changing them today—thanks for the tip!

5

Yeah, definitely check the plugs and coils first. You’ve got the 6R80 transmission, right? That’s a solid transmission. If it were a transmission issue, you’d probably notice problems at lower speeds first.

6

@Ciel
Good to hear. I’m only noticing issues in 5th and 6th gear right now. Thanks!

7

Bit of a gamble with these things.

I did the spark plugs and ignition coils, but the issues continued. Then my 6R80 decided to shift from 6th to 1st on the highway, and that blew up a turbo… that was a fun day.

8

@Oran
That’s my worst nightmare, haha. Did you notice any issues at lower gears beforehand?

9

Blake said:
@Oran
That’s my worst nightmare, haha. Did you notice any issues at lower gears beforehand?

Nope, no problems at all. But to be fair, I had 200k miles on it, and the truck had a questionable maintenance history since I was the 5th owner.

10

@Oran
Had similar issues with my '11 Ecoboost. After the transmission recall work, all the strange shifting problems disappeared. It’s been a few years now, and I’m back to just replacing plugs and coil packs as needed.

11

@Ben
Unfortunately, I was outside the warranty period for that recall. It sucked.

12

Mine gave out around 160k miles. Before that, I noticed it would slam pretty hard at low speeds, like when rolling through a parking lot, but it was fine on the highway.