I have my IS in the shop all torn down due to oil consumption and carbon buildup on the pistons.. As of right now, Lexus wants do replace all the pistons and rings.. Bad design of pistons has caused oil to get around piston rings and burn oil... This in turn causes spark plug misfires and oil burn and that carbon build up on the tops of the pistons...
Rebuilding the motor in the local shop vis the "hospital sterile" environment that it was originally built in at the factory is not to my liking..... I'm not OK with this... Piston rings just don't go bad in 35K... I would not expect this from a GM product, but wouldn't be surprised... BUT, in a Lexus, I'm very surprised and very shocked this has happened....
The Lexus dealership where my car is has 2 other IS's in for the same exact thing... Really??
Anybody else been through this?
Vance

Repost of... Lexus 4GR-FSE Engine Carbon Build-up (merged threads)

Yeah post in thread recommended, but since u bring it up my car been in the shop since last Wednesday for the same problem.
Original brought it in to get the Cam gears and carbon build up checked out, they called me a couple days later stating one of the cylinders were miss firing and they will be replacing the piston.
What I would love to know which I forgot to ask is if they replacing one or all the pistons.

I have had the same problem but below is my story and how I got it resolved without paying a cent from the dealer.

https://www.clublexus.com/forums/is-...ne-repair.html

I hope this helps.

The piston rings haven't failed, per se, the updated/improved pistons and rings are an attempt to reduce the amount of carbon build-up from the D4/GDI system. This issue is common across almost every DI engine from many manufacturers (Audi/VW have had worse problems than Lexus).

I'm glad Lexus is trying to do something about the issue for owners.

Jeff

yup. mine was in as well, took them two weeks to get the car back to me. only had 39000 miles at that time.