2014 IS 350 F sport with severe carbon build up at 79K miles. Anyone used a cleaner or just had Lexus take engine apart to clean? Costs?

 

That's really weird since the 350 engine is dual injection and should be mostly free of carbon build up problems, especially at only 79k miles. How did you/mechanic make this determination? Not doubting you, just curious and if you have pics that would be cool.

 

Well it's direct and port fuel injection apparently. My check engine light came on and before the day was over the light was flashing and car was vibrating and skipping. After investigation, the mechanic determined it was severe carbon build-up which is common apparently. Since posting the question, mechanic has run a cleaner thru twice to remove carbon. Walnut blasting/GDI service is what Lexus recommended.

 

Its actually very rare on the 3.5L. The port injection usually eliminates most buildup. Yours might be the only one i've read about here in the 3IS forums.

 

Well I don't have the best of luck so go figure.

 

I think my car has the same issue as it is stuttering when accelerating slowly at low RPM, my car now has 115 miles and I didn’t add cleaners since long time.

 

First I ever heard of this on a 350. Take pictures and post them on here!

 

Were you using cheap gas? Typically tier 1 stuff has cleaners that prevent buildup (Chevron, Shell).

 

RR Racing said their is350 they did their supercharger kit on had carbon buildup from babying it, so other than that this is the first one I’ve heard. How often do you go full throttle? What gas do you use? Did your mechanic say the carbon was reduced at all by what they did?

 

Not to doubt your mechanic...actually I'm blatantly doubting your mechanic...but carbon buildup on the IS350 is not a common issue at all...like zero issue.
The 2IS250 it was a very common issue until Lexus rectified the problem in 2011, before the 3IS was built. But the 250 had direct injection only...which wasn't the issue, but it sure didn't help.
The IS350 has been using the same engine since 2006 and there have been no reports of carbon buildup...at least none I can remember seeing.
Some carbon buildup in all engines is expected as it's a byproduct of combustion.

As a previous poster mentioned, how did the mechanic determine this? Did he remove the intake manifold to physically see the valves? Did he remove the spark plugs and use a bore scope of some kind?
If the buildup is "severe", running a cleaner through the tank is going to do squat...literally.

Obviously there is an issue with the car, and maybe you are the first one with carbon buildup on a 350...but I'm not liking the Vegas odds on this.
I would recommend a second opinion unless the mechanic can provide you tangible proof of the carbon buildup. Unfortunately his diagnosis sounds like the result of some quick Google searching and not understanding what he read...meaning distinguishing between engine models.

 

Good post. The mechanic should have known the 350 and 250 are very different in terms of engine, and should have clarified that for you instead of just saying it was common. Then again, he might have just been trying to ease your concerns.

Maybe, once it's all cleaned up, the occasional Italian tune-up would be a good practice?

 

Check this out. It’s RR Racing’s post on a 2014 350 with carbon build up.
http://blog.rr-racing.com/news/2017/...on-lexus-ecus/

 

I noted this comment from the article:
"We are fairly certain the car was run very easy, probably with a lot of city driving, and maybe even on 87 octane for a while. Pulling the plugs and inspecting the pistons showed a bit of excessive carbon buildup."

Assuming they are correct in their statement, then this would happen to any vehicle if it was treated like this...especially with the severely lower octane rated fuel.
Even despite their comments, there was no mention of the vehicle running condition except the KCLV reading, which was still within parameters for the vehicle, just not ideal. I'd like to think that vehicle probably drove just fine.
It probably didn't have the best fuel economy though...and maybe not the same pep as a well maintained 350.

 

To the OP, if you haven't already, take their word for it on the above posts.

Don't think anyone is implying your mechanic is "bad" just not well enough researched or diagnosed.

I've had this several times a mechanic throws out info which used to be true, or is true but on another model.
I just went through this thinking I knew about common issues in Hyundai. Then I realized that was mostly just 1-2 models and several years ago. Oops.

 

I think there is a common misconception -- something along the lines of DURDY BURDY LEXUS NOW USES DUAL INJECTION NO MORE CARBONS!

Not really. Dual injection mitigates, not eliminates.

The oldest 3IS 350s are now 5 years old, and most people drive about 10-12k a year--so of course you won't hear of many yet as most of these cars have 50k max. But now 70-80k is starting is becoming a thing, and so are carbon cases.

The 8AR-FTS is dual injection and someone posted two low mileage 8ARs taken into Lexus and replaced under warranty, being stripped down, due to carbon build up throwing misfire codes.

So don't think you're necessarily out of the woods if your car has port injection in addition to direct injection. And really you're never out of the woods as long as gasoline is a thing. There's just varying degrees of delay.

I think if you drive your car gently, it never really helps you. There's that as well.