Car vibrates at speeds, under load only

[Silver99camry]

Hi,

I am trying to solve a puzzle here. My car is 4cyl 99 auto. When I drive at highway speeds >45-50 I get some vibration. It's not misfire, I've experience misfire before. There is no loss of power, no CEL. Vibration is not RPM but load and speed specific. When going slow (<40), I do not feel it, but it builds with with speed. It only occurs when throttle is applied and it varies with load (throttle position). If I take my foot off the gas pedal, or shift into neutral and cruise, it goes away. If I just put it in N and rev up, there is not vibration either. Any ideas?

Could be mount, what else? Can it be bad half axles? How can I check?

Thanks,

[Silver99camry]

forgot to mention: idle is smooth and I have a small exhaust leak before the muffler, but I don't see how it can make a difference.

[JohnGD]

Worn inner CV joint? Maybe wheel balance? If the latter try moving front tires to the back. If the vibration changes or disappears then you know.

[Silver99camry]

Originally Posted by JohnGD

Worn inner CV joint? Maybe wheel balance? If the latter try moving front tires to the back. If the vibration changes or disappears then you know.

I doubt it's wheel balance, since it occurs under throttle only. W/o throttle at any speed -> no vibration. Plus, new tires were installed and balanced recently and all the weights are in place. I lifted front and rear tonight and all the wheels are rock solid, no play. Also, if I go around in circles, no clicking sounds.

If it's a worn inner CV joint, will there be any play in the wheel if I try to move it? Only passenger side has inner CV joint, right?

I detected some cracks in the passenger side motor mount, I'll try to replace it next to see if it helps.

Any other ideas? How to check inner CV joint?

Thanks

[Silver99camry]

I also checked transmission mount and it looks good. One more data point, at a given speed, vibration depends on the gear. The higher RMP, the worse it gets under throttle.

[akhoundog]

does the sound change immediately as the gears change or does it slowly build momentum as the speed increases?

[Silver99camry]

Originally Posted by akhoundog

does the sound change immediately as the gears change or does it slowly build momentum as the speed increases?

If I step on the gas hard, causing gear change, RPMs go up instantly, so does vibration. If I stay in the same gear and apply the gas then RPM go up slowly and so does the vibration. At a given speed, vibration depends on the throttle position and gear. With no throttle, no vibration.

What are the symptoms of bad inner CV joint?

Thanks,

[Mister_Perkins]

To check the inner CV joint You would hear a clicking noise also. Climb under the car and grab the Axle section towards the transmission and push up and pull down on it if it moves and you can feel it making a "Popping" feeling then you've just confirmed the inner CV joints are wore out.

With a bad CV Joint you would not feel it by moving the tire, you have to physically grab the Axle (Part between the rubber boots === CV Joints)

[Silver99camry]

Thanks, I'll check that. с Новым годом!!