2016 RX450H F-Sport Engine Rattle/Knock Update from Lexus

[robpace]

Car was taken back to Lexus for tests last Saturday and they finally heard the Knock/ Rattle and Vibration that happens when restarted after leaving it for roughly 15 mins after Engine Switchoff from warm.

No Noise or Vibration when starting Car with Cold Engine !

The Knocking/Rattle/Vibration always goes after about 15 Secs after Engine Starts.

Just had their Service Manager on the Phone, and he said they have run lots of Tests on the Engine and say it is a Characteristic of that Engine, mine being a bit louder probably due to the higher mileage (75000) and they are getting similar Noises from other Models.

Their Master Technician has said it's something to do with a Cycle the Car goes into where the Fuel Injectors do something when the Timing is Advanced or Retarded to get the Catylitic Converter to the right temperature ???

Think that's roughly what i heard !!

They have done a Software Update lowering the Fuel Pressure (??) to hopefully lower the noise and vibration when it is in this Cycle, and are going to deliver the Car back on Friday.

Lexus have said give it a go for another week to see if it's better, and will take the Car back if we're not still not happy and cannot live with the lower Noise/Vibration, but have assured me this noise from the Cycle is perfectly normal and their is nothing wrong with Engine.

Will Update next week !

Any thoughts ?

Thanks

Rob

 

 

 

[ColinBarber]

40 minutes ago, robpace said:

Their Master Technician has said it's something to do with a Cycle the Car goes into where the Fuel Injectors do something when the Timing is Advanced or Retarded to get the Catylitic Converter to the right temperature ???

I think this is part of cold start, so not sure this is totally relevant.

There is a TSB for noise/vibration related to fuel pressure/pump but that states it occurs when driving. Maybe they aren't entirely sure so are trying a few things, or maybe the issue the TSB addresses manifests itself with multiple symptoms. All you can do is see how it goes for now.

[Herbie]

Gut feeling says that's bull****

I'm only a hobby mechanic but surely that can't be right?

[robpace]

20 minutes ago, ColinBarber said:

I think this is part of cold start, so not sure this is totally relevant.

There is a TSB for noise/vibration related to fuel pressure/pump but that states it occurs when driving. Maybe they aren't entirely sure so are trying a few things, or maybe the issue the TSB addresses manifests itself with multiple symptoms. All you can do is see how it goes for now.

That is what i think he said Colin, his words to describe it were 'Perfect Storm !'

[robpace]

8 minutes ago, Herbie said:

Gut feeling says that's bull****

I'm only a hobby mechanic but surely that can't be right?

We are going to give it a go for One Week, and ive told them if we don't like it, and they have agreed The Car will be returned next week for good.

Must admit, Andy the Service Manager is a very nice fella and says they will do all they can to find us another one.....Only problem being its got to be Grey with Black Interior and no more expensive!!

 

[Spock66]

I am new to Lexus and this forum, but in 30+ years of car ownership the "it's normal, they all do that" is typical of the response from the UK motor trade when they can't diagnose and successfully resolve a problem.  My 2018 RX450h with 12,000 miles does not do this and no one else has piped up either to say it's normal. As to the 75,000 miles statement that is just rubbish, a car of this age and mileage should either function correctly or has a fault.

To me it looks like you may be running on only 5-cylinders when this occurs, this would explain the excessive vibration, but I would expect this to be easily diagnosed and could be due to a spark plug, coil pack, injector, wiring etc. I would ask them if they are 100% sure this is not the problem and also get the service manager to demonstrate this on another vehicle as he has stated.