2015 Honda Pilot, V6 auto, 110K miles. This has been an ongoing and growing problem for probably a few years.
When hitting 65+ mph, the engine starts shaking pretty badly, causing dashboard rattles, steering wheel shake, and you can feel it in the floor. The issue happens when accelerating moderately (like trying to maintain highway speed) and goes away when letting off the gas. At certain times, this leads to a VERY bad shake when braking, and it feels like the rotors are badly warped (which they are not)
This is NOT tires, which are new. I've also tried rotating them. The rotors are also new. Recently had the timing belt and water pump replaced. I didn't think that was the issue (was hoping) it was just routine maintenance.
I've replaced the motor mounts, thinking that was the issue. It did seem to alleviate it at lower speeds, but the problem persists.
I've had the car in the air and have inspected the front end parts. The wheels have no give at all, side to side nor up and down. But I don't think these parts would cause the problem because this happens during acceleration.
I can't rule out CV joints, but I've done the parking lot test, going in circles with the steering wheel cut all the way.
No ODBII codes.
I've had it to two mechanics who gave no/bad diagnosis. One said to replace the rotors - which felt pretty dirty when I threw away the old, perfectly good ones.
You say, it's not the tires, but the weights are know to come off on occasions. But you normally would feel that regardless of the acceleration.
Worn shocks/struts can cause oscillations in the front end at particular speeds when you hit that sweet spot (resonance frequency).
The rotors can become warped prematurely. If you're getting the shakes at that high of a speed, the warpage may not be noticeable without a measuring device.
The fact that it shakes without the brakes applied, suggests that it's either not the brakes, or that you have multiple problems. I have 2015 Odyssey, similar in design as the Pilot. I replaced the rotors on that due to warpage at about 75k. In less than a year, it developed a slight hint of rotor warpage. Hard to say for sure, since it's so subtle and I don't drive the car often enough
You also said that the engine shake. Do you know that for a fact?
Also, you said the rotor are not warped. Do you know that for a fact?
BTW, do you feel the shake in the steering wheel (as in warped front rotors)? Or does the whole car shakes, but not really in the steering wheel?
Is it a 4WD?
I know it's not the tires or brakes, because both were new and made no difference immediately after replacement.
I know for 95% of a fact that it's the engine because I recorded the inside of the engine compartment with a Go Pro and observed it going back and forth pretty wildly. The 5% hedge is because this recording was before I replaced the motor mounts. I thought for sure it was the mounts - and one had a good crack in it.
It is a 2WD. The steering wheel shakes most, but the whole car shakes.