Hello,
I am looking for some help. Extremely frustrated with my 2007 Lexus RX 350 FWD with only 100k miles on it. Pretty much, it shakes on acceleration, mainly noticeable around between 10 and 15 mph. Front end shakes somewhere. Not in felt in the steering wheel but more in the floor maybe? When you let off the gas, it immediately stops, so only as you are on the throttle. Anyways, I had issues last year with shaking and, since then, I have had new brakes, new tires, new CV axels on both sides twice, and now new motor mounts all around. It isn't a violent shake or anything, but it is annoying that it does not accelerate smoothly like it should. Not sure what else to do, but I am getting burnt out with sinking money into a car that I bought for reliability. If anyone else has had this issue and or knows anything, please let me know. I WANT to love this car...
Thanks

 

How old are the plugs and coils?

I recently swapped a set of original coils with new OEM manufacturer on a 134k mile 2011 Honda Fit (wasn't failing, no codes) and was amazed the difference it made ( link ). Don't know if that will translate to other brands such as Toyotas.

Unfortunately its still parts cannon approach and rear bank 3 coils+plugs are hard to get to on the 2gr-fe

 

Investing heavily in expensive coils and putting in the 8 hours to get to the rear ones in hopes of it solving a problem is nt a prudent move. If it were due to coils that would show up with codes popping up. Have you run codes to see what comes up?

 

and who is diagnosing the car? dealership ? a shop.. you might need to find a good mechanic for proper diagnosis. Most mechanics currently are just parts changer with no diagnostics skills and do the parts cannon approach (anyway the customer will foot the bill)

 

OR.... run the codes and post the here as there's a huge knowledge base of experienced guys who know RX330's and RX350's. Running codes is free, quick, and easy. Highmiles is correct most mechanics, especially dealerships, are not trained to diagnose cars they are trained to bolt on new parts which is a VERY expensive path to resolution.

 

I know you mentioned it had already been checked/repaired twice already. But this sure sounds like a stuck brake caliper either on right, left or both front wheels. This is usually caused by poorly or improperly lubricated slide pins. The brake disc pads then grab, or don’t release fully after taking foot off brake and just starting to accelerate. This will also cause disc brake pad wear (or uneven wear) on that side of the car too. It’s the part of your question where you say “it stops on its own” that causes me to think brakes, not ignition parts like spark plugs or coils.

 

Floating calipers wants to twist perpendicular to the rotor under braking. So calipers mount need to counter this force. Toyota/Honda caliper use beefy pins anchored only on one side (inside of the rotor) with low clearance to counter this twist. In the past, I found the factory yellow grease on my 11 Prius seized up by 50k miles (many reports of this when I searched in various Toyota models) SIL-Glyde silicone grease has never seized up so far close to 100k miles.

Other cars use an additional tensioning spring to anchor the caliper on the outside (of the rotor) against the caliper bracket so have dual anchor points to counter the twist motion. Caliper pins don't need the tight clearance for this design and properly floats even without grease (unless seized by rust I guess). Here is a pic of a 2000+ Volvo I worked on with this design ( link ) This design is much more robust and forgiving... But many people make the mistake of not tensioning the outer spring and get poor bite as the caliper twist under braking (Myself did this once to learn about this design haha)