hi i have the k900 v8 version and i notice that in normal mode if i punch the gas the car would leave a cloud of black smoke or if in sport mode it leave some black smoke at high revs about 5k to 6k rpms. i wonder if anybody else notice the same or if it is normal? i use shell 93 octane

Hi,

good observation. I would believe this would be "soot" as it is know around the car world that is produced by gas direct inject (GDI) engines. There is nothing wrong but it can stain the bumper of lighter color cars. Usually a little soapy water and it will come right off.

yeah the staining is annoying, i was thinking that it was running too rich on fuel, that maybe a K&N filter will help with that

I wouldn't think a K&N air filter would make a difference in the air/fuel ratio. Everything is controlled by the engine control module. Even if you took the air filter the ECM still determines how much fuel to inject. Allowing more air into an old carburetor engine will change the A/F ratio but the K900 has a direct injected engine.

I noticed the same thing on mine the other night under WOT!

This is normal for GDI engines from what I understand.

I did notice this as well on our Cadenza but not on our Sorento. Both were '14 with GDI. Have not seen it on K9.

traveling behind a lexus two days ago. He punched the gas to get around some cars,
left a much bigger cloud of black smoke than my car has ever had