My 2016 CX5 Grand touring (2.5L T) is aggressively shaking on the highway at 55MPH+, and also when I am going up inclines at lower and the same speeds. I just replaced the engine at 135k Miles after the third cylinder and head gasket blew. the used engine I replaced it with had 95k miles on it.
No service or dash lights are on.
I like working on cars myself.
Rotors are new. breaks are new. tires are new. I've driven it 3000 miles since i replaced the engine and started experiencing this problem.

First post im excited for the feedback

 

On the "shaking" up inclines at lower RPM's, some questions:

1. Have you tried using the manual-shift mode, up those same inclines at the same speeds? Would be worth seeing if a lower gear (higher RPM) eliminates the shaking you're experiencing.

2. Have you tried "Sport" mode, up those same inclines at the same speeds? It boosts the RPMs as compared to regular (non-Sport) mode.

I have a 2016.5 GT AWD. It shakes, shudders, "growls" a bit, at lower RPMs. Particularly when going up hills where the transmission hasn't decided to select an appropriate gear for the situation. In my experience, in "normal" (non-Sport) mode, the transmission shifts from 1st to 2nd gear at about 8-9mph. Should wait until 18-20mph or so, if heading up an incline, if using moderate throttle. But it doesn't. It aggressively seeks fuel economy at the expense of shuddering with an improperly-selected gear. Going to the manual shift absolutely eliminates this silliness; and using "Sport" mode until getting to "cruise-control" speed also works well.

Might be all that your "shaking" issue is. At lower RPMs/speeds, that is.


Shaking at higher speeds might well be tied to tire balance. You've got newly-installed tires. I'm wondering if they're out of balance. I've only had the car since the first of this year, but I've since swapped to different tires. In both instances, the tire install and balancing included a "road force" balance (ie, with the Hunter Engineering equipment at the alignment/tire shop). Did the same with a Miata, some years ago. All tire installs done with a Hunter "road force" tire machine. Worth asking your shop, about the tires' balance.

 

We need additional information OP. Exactly when did the shaking start:

Right after the engine was replaced?
Right after the brake job?
Right after the new tires were installed?
Some other time?

What year is the engine? Obviously it’s not the turbo.
Has the transmission fluid been checked/replaced?