rough engine sound at low throttle

maneesh · September 20, 2002

92 Ls 400 with 156k up. Full LSH.

It's been a year since A service, and engine is starting to sound a bit gruff. Very noticeable at lowish speed, have normal silky engine note, but now additional rough noise (sounds as if something is going round and round in the engine). Noise isn't always there, changes acoustics along with engine speed. Also, have noticed it's worse at startup from cold (engine idling higher for longer), but still returns when warm.

Has anyone experienced the same?

I have had EGR pipe done 4 years ago, water pump 4 years ago, power steering pump 1 year ago, steering rack 2 years ago, front springs 2 years ago. I am not sure what it could be related to.

Steven · September 20, 2002

i experience the same problem... until my mechanic said the car sounds normal and everytime i think of it the worse it gets

I give mine a oil change every 3 months and the oil always is always golden

the ticking noise will be the injectors.. so thats normal

car will sound rough when cold as he oil needs to thin up so it can protect all of the bare metal... when the oil is cold it is thicker, thus starving the engine for a minute or two while everything warms up.

Rodders_UK · September 21, 2002

Have you tried synthetic oil Steve?

Steven · September 21, 2002

yeah i use magnatec.. but what i was getting at is that it may be phycological... there is nothing wrong with my car... its in my head that the engine is rough

Monster-Mat · September 21, 2002

... there is nothing wrong with my car...

hmmmmmmmmm:D

Steven · September 21, 2002

there aint... running sweet at the moment...

maneesh · September 22, 2002

I'm obsessed with quiet cars now that I have the 400, but this is a definite new noise which my passengers have noticed as well.

It also coincides with a lack of power at very low speeds (as if the roughness is not preventing the air/fuel mixture through properly).

The car is up for a B service in the next 1000 miles, but if I ask Lexus what's wrong, they might come back with a four figure price tag!!!

I know it's an old car (10.5 years old now), but this doesn't sound right. I do remember the car sounded rough after I bought it, and the EGR pipe was replaced under warranty, and the engine has been super smooth since then. EGR pipes don't need to be changed that often do they?

The noise doesn't seem to interfere with fuel flow (in terms of the gas pedal feels normal), but perhaps I should buy one of those fuel injector cleaner things you add to the petrol tank?

I wonder if it's got anything to do with the fact that I took the car 2 months ago to Kwik Fit and had an oil and filter change using Mobil semi synthetic. I have always used Lexus before that. However, this roughness was there prior to Kwik Fit visit.

By the way, where can I find out details about Gold benefits? I would like to join up providing I can get servicing discounts at a London dealer.

Cheers