is250gurl

really thinking the extended warranty is needed now :-(

Infra

iTrader: (1)

The issue of carbon build-up in direct injection engines is well known. Check out this thread on the Audi 4.2 FSI.

http://www.audizine.com/forum/showth...-up-Megathread

The IS250 does not have port injection like the IS350. What this means is that no fuel, no fuel additives, and no fuel cleaners will ever pass over the intake valves. Over time carbon deposits can build up on the valves.

Supposedly a catch can can help with this problem if you have had it occur in your car.

NWIS250AWD

Good to know. If they only made the 350 in awd. Options are ext warranty, pay the 1800 plus cleaning bill while out of warranty or change cars.

yutnaka

[Supposedly a catch can can help with this problem if you have had it occur in your car.]

Infra I agree with you there on this. My car threw a check engine light, and when I took it to the dealer they told me I had too much blow-by. Which made the 02 sensors throw a code. They also told me not to use synthetic oil and to use blended oil. Has this happened to anyone of you guys? I am guessing this will lead to a stumbling issue over time. Mine stumbled once, but I put on Bg44k and it has not come back.

shui3000

crap, checked the audi forum, now i'm scared about this happening to all of our engines.

is250gurl

me too!!!!

lobuxracer

iTrader: (2)

Without knowing how Audi is doing EGR, it's foolish to think Lexus will suffer the same fate. The way Lexus does EGR means the only way to get carbon build up is through reversion into the intake port. Reversion is dependent on a number of conditions being met, and if Lexus has done their homework, you won't be driving normally under conditions promoting carbon build up. If Audi is using external EGR (and the Audi forum seemed to mention they might be), getting HC build up on the intake valves is to be expected.

There are other manufacturers doing GDI and not having these issues. Some have been doing it a very long time (Mitsubishi) without these problems.

What would be most interesting is to hear from Lexus techs who are working on these engines. I'd like to know what they're seeing in the field and if it matches what Audi is suffering. I have my doubts.

Last but not least, water injection would completely remove these deposits very quickly.

hades281

There are big differences in Audi's setup and ours.

I had a VW with the 2.0T engine. It used about a quart of oil every 5k miles - normal for that engine, with a good amount of it being sucked into the intake via the PCV valve. Because the engines are direct-injection, there is no fuel injector spraying the intake valves to keep them clean, so the buildup occurs. I took off the PCV hose that goes to the intake and it was just soaked with oil. Turbo cars have more complicated PCV setups and this phonomenon (oil in the intake) is a lot more common with them. Thats why catch cans are popular in aftermarket, and the VW actually had an oil separator, though it obviously was not near effective enough.

By contrast, my engine uses (seemingly) zero oil between changes. The IS250 only has 6 injectors -- only the IS350 has the dual injection -- so while IS250 owners (like me) don't have the benefit of a fuel injector cleaning the valves, it should stay a whole lot cleaner in there anyway than the 2.0T.

Personally I don't believe that carbon buildup is causing rare, intermittent problems like this one in low mileage cars. The carbon can't build up so bad as to cause impairment of the valves and then suddenly "break off" and everything runs great again. Something else might be going on.

Filsee

I had the same thing happen on my 07 250 RWD at 22k, the dealer replaced the exhaust valves and the car has been running fine since. Service manager said it was a known carbon deposit build up issue. Switched the valves to updated 09 design (the fix). I'm only at 27k (6 month later) now so I can't comment on longevity of the fix. I will dig up the service report to see what exactly they listed as done. The service manager did mention that he had the same thing happen/done to his car.

Clay Easto

Did he say if using fuel system cleaners would help?

Clay Easto

Any updates? Anything????

Filsee

The service manager did not mention anything about cleaners, he just said that with the updated valves the problem should not come back. I just dug up my service report, and the code that was thrown was P0300. The new exhaust valves used are part number LEX 13715--3110-2. The operation code for those interested is LEXOPCODE: 141011.

NWIS250AWD

Thanks for the info. I am pursuing Lexus to do the valve replacement instead of the bandaid fix of "just the cleaning solution".

meefer

iTrader: (8)

Does this mean my 250 RWD is some kind of time bomb?

75K miles never had an issue with it really, certainly not a CEL. Maybe a rough start once in a while? I go WOT, past 5K rpm at least twice a day.

Clay Easto

This just happened to me this morning, just short of 39k miles.

Came to a red light. Engine started shuddering while I was at the light. Started to accelerate away from the light and the Check Engine light started flashing, Check VSC showed in the display, a red exclamation point lit up. The car wouldn't go over 40 mph. Stopped at the store I was going to & called the dealer. Started the car up again and it was fine. It is at the dealer now.

I am not happy about this. I suspect I will keep the car until the extended warranty runs out and sell it.