Carbon Buildup?

[Ego93]

I had a Check VSC light come on my 2006 GS 300 about a month and a half ago. The car wouldn't accelerate past 40mph and would begin jerking as if a fuel line was clogged. I took the car to my Lexus dealer to have it checked out. After a day and a half, they came back with a response of a valve spring being broken. No explanation of why, just that it was covered under warranty. So they take the car for a test spin after replacing the spring and the car starts acting up again.

Two and a half days later they're telling me that the valves aren't closing properly so they will have to take the cylinders out to see what is going on. Before any of that can be done, Lexus has to send a rep/engineer to check their work and make sure all measurements are done correctly. Long story short, its been in their possession for this entire time. I spoke to the service rep today an he says they are having to remove carbon buildup from the cylinders and basically have my engine block off. Apparently, it's a very tedious process and are only able to clean 2 cylinders a day.

My question is, what could be the cause of the carbon buildup? I've read on other forums that based on the way that the fuel is injected, it's impossible for bad gas to be the culprit. Could it possibly be oil? Regardless of an answer, what assurance do I have that by them taking the engine apart like that nothing else will go wrong?

[1990LS400]

For one, it is impossible "to take the cylinders out" - engines aren't constructed like that. And unless they are using rare albino mice to lick the carbon from your cylinder walls, it most definitely doesn't take half a day to clean a cylinder.

I think you are being fed a complete ration of s-h-i-t by your dealer. If your car is still under warranty, demand that your car be bought back at a reasonable price. No competent or honest dealer would keep a car for 1 1/2 months to fix a problem like this. Maybe 1 1/2 days ...

[intakerGS]

Things that may contribute to- or speed-up carbon buildup: lazy thermostat, O2 sensors, overly rich mixtures, excessive oil consumption, abnormal combustion (detonation), faulty ignition system, bad valve guide seals/springs, heavy foot driving, non synthetic oil.

rare albino mice to lick the carbon from your cylinder walls

LOL

[Ego93]

Thanks for the help on this. Now that I think about it, 1-1/2 months is a long time to have a car for repairs. Me thinks I'll be looking at an attorney. Something just doesn't smell right. 1990LS400 you're mice comment had my wife and I rollin'. Much appreciated!