Judder on Transition from Electric to Electric/Engine...Help

[Mjtray]

Hi there

My first post.

My relatively new to me RX400-H which is a 2009 vehicle with 86,000 and full Lexus Service History has recently started juddering/stutters when you accelerate with a light throttle from pure electric to running with electric+engine. It literally just judders as the engine kicks in and then clears and only when you accelerate on a light throttle at very low speeds, ie when you are using pure electric to move slowly in traffic and when slowly building up speed. The judder can be very noticeable at times and on other occasions its very slight. If you accelerate hard, it switches between electric to electric+engine with no judder. 

If you are cruising and come off the accelerator and coast and then go back onto the accelerator and use both electric and engine the problem never occurs....its only at very low speeds.

I spoke to a Lexus specialist and was looking to book the car in with them but they didn't seem that interested, but they did mention that it could be Coil Packs or Flex Plate in the Gearbox.

Re Coil Packs, as there is no Engine Management Light on its hard to diagnose a failing Coil Pack...or at least I think its difficult to diagnose....i could be wrong.

2ndly the Flex Pate....not sure on this one, as I'm sure if it was a Flex Plate it would cause Judders at all speeds and be making a rattling sound from the gearbox....anybody have any experience with failing Flex Plates?

Lastly...any recommendations on a good Lexus Specialist in and around Berkshire/Oxfordshire/Surrey/London etc...I'm prepared to Travel and leave the car with them. I tried calling an advertised Lexus Specialist in Maidenhead 5 times today and just went to answer phone, so gave up. The other specialist in Watford area never got back to me.....Should I just suck up the costs and book it in with Lexus

 

 

Look forward to getting some thoughts on this Judder problem

 

 

[Herbie]

36 minutes ago, Mjtray said:

I spoke to a Lexus specialist [...] but they did mention that it could be [...] Flex Plate in the Gearbox.

Hmm... I don't think there is a flex plate in the CVT gearbox so I'd maybe give that "Lexus specialist" a wide berth.

Could be loose or degraded engine mounts maybe?

[royoftherovers]

Mjtray, How did you acquire the vehicle?

An extremely important question in the context of your problem(s).

[Mjtray]

Private Sale

[royoftherovers]

31 minutes ago, Mjtray said:

Private Sale

Sad news Martin, but good luck anyway.

Try people who specialise in Toyota, Suzuki,Daihatsu etc.

 

[NemesisUK]

17 hours ago, Herbie said:

Hmm... I don't think there is a flex plate in the CVT gearbox so I'd maybe give that "Lexus specialist" a wide berth.

Could be loose or degraded engine mounts maybe?

Might this be a 'flex plate'?

 

HYBRID TRANSMISSION SYSTEM DETAILS TRANSMISSION DAMPER.pdf

[Mjtray]

I would be surprised if its the flex plate as I would expect to hear a rattle coming from the gearbox or feel vibration even when driving, but there is non of the above. 

[NemesisUK]

I'd second engine and/or gearbox mounts

[Haylands]

The PSA Group double clutch gearbox uses dry clutches, they have the exact judder you talk about at very low speeds, They claim it "is a feature of these gearboxes sir...!!!"

If the damper above is worn or has been contaminated by oil then I could see it could cause your symptoms.

Try a few heavy throttle take offs, which should clean anything off the damper, and see how the judder is directly after....

Might be a mile wide of the mark but if it does improve it might help diagnosis....

 

Good Luck..