Noise/hesitation When Pulling Away From Standstill - Mk1 Rx300

MatthewH · May 27, 2014

Hi all, I have a strange problem on my 2002 RX300. Occasionally, when moving off from stationary the car the car drifts forward as normal when I take my foot off the brake to apply the throttle, the car accelerates under throttle for maybe couple of metres but then an audible grinding / juddering noise comes from the front end, and the car hesitates as if being held back, the front end dips forward as if the brakes are being applied or traction is being held back. After about one second of this noise it stops and the car drives away as normal.

This happens maybe once in a journey of 50 miles, and it's hard to "make" the car do it to order which is why I am stumped. When it does happen, it's 99% of the time in stop start traffic, so moving a short distance, stopping, moving off again, and so on.

My first thought was the ABS sensors at the front being fouled, so I cleaned the front ones of debris. That appeared to work for a few hundred miles but the problem returned (if it ever went away). I thought perhaps binding brakes, or another part of the ABS system mistakenly restricting traction. The front discs and pads are not Lexus items, but are not worn excessively.

On one occasion it made the noise for a particularly long and loud judder as I turned the very sharp uphill bends in a multi storey car park - that made me think of worn suspension strut mounts or bushes, or even wheel bearings - but it passed its MOT no problem only a few months back.

Has anyone had a similar problem? Anyone know of a likely cause?

theboyjordan · February 21, 2016

Hi, have the exact same issue. Did you ever find out what the problem was? Many thanks

MatthewH · February 22, 2016

Yes I did. My local garage was useless and could not figure it out. I took the car to an auto electrician and they fixed it, it took a couple of hours' labour. The problem was the level and even seating of the ABS sensors. Corrosion had got in behind the area where the sensors mount, disturbed the mounting surfaces such that the sensors were not mounted flat and perfectly evenly. Unless they are absolutely flush, the sensors think that the wheels are rotating at different speeds like they were skidding (as in normal driving, where the wheels are all turning at the same speeds, the sensors are all giving precisely consistent wheel speed readings). So the ABS was activating when it shouldn't have been, and that is the noise and pulsation you are getting. The sensors are giving uneven readings and tricking the car into thinking that it's wheel spinning or skidding.

The guys removed all the ABS sensors, gave their mounting areas and the bodies of the sensors a good clean and smooth-down, and remounted. That was it - it has been fine ever since, with no recurrence. If you are planning on doing this job yourself, be aware that when mucking about under there myself, I destroyed one perfectly good sensor as they are very tricky to get out without proper tools and access on a ramp. At over £100 a piece for even aftermarket ones, I gave up at that point and sought garage help.

Hope this helps!