ajfinoak

My '08 IS 250 with 54k miles will be 9 years old this week and thus my 9 year warranty extension for carbon build up repair will end. I have had a few episodes of brief dropped idle speed and car shaking every few months but never a check engine light. My understanding is that Lexus won't repair it without a check engine light and code, correct? Also, what are the repair options and cost if/when it gets worse besides a full rebuild that folks may have done. I realize that may not cure the underlying engine issue but am wondering if keeping the car is worth the risk of very expensive repair.

SQLnovice

I have a 2007 IS with 78k miles and I don't think I have carbon buildup issue. Since last year, I've been using a gas additive (Made by chevron). Every few months I would use two containers in a full tank of gas consecutively. Especially if I'm going on a road trip where I'll be driving on the highway. The first time I did this I noticed a significant difference in throttle response. I recently started putting "Recreational fuel" which has no ethanol. I hope these changes will prolong the life of my motor.
Don't know if any of this will make a difference, but this is what I'm doing to hopefully prevent any future buildup.

ezbmr

I would think that Seafoam would help. I can't see that an additive would help, since most of the problem is with that side of the engine not getting a cleaning with port injectors. There is always going and getting the walnut blast, I have seen as little as 400 for it.

Mrfix

Seafoam works the best.

What I would do is this. Get the can of Seafoam that comes with the straw. It will slide into your air intake after the MAF sensor and before the intake manifold. Run it through and it should clean the heads a little. I would also get a regular can and run about 1/3 of it through the PCV hose (very slowy). Put the rest in your tank.

Do this about once a month for a while and it should definitely cleanup the top half of your engine where the carbon builds up the most.

It's a cheap fix for an expensive repair.

Great video on how to.

davyjordi

when i had my 2IS, the dealership repaired the vehicle without a check engine light on. bring it to the dealership, explain what's going on, and hope for the best. if you have a solid relationship with your service advisor, there shouldn't be too much of a problem having the band-aid placed.

davyjordi

the fuel doesn't flow over the valve as it does in the direct- and port-injected 350 engine, so while adding detergents won't do any harm, they're likely not going to do much good either.

SQLnovice

Thanks for the info. I'll save my $$$ and not do this anymore. I guess i'm lucky to not have any carbon buildup issue as of yet.

Is it possible to not experience carbon buildup problems with the IS250, or is it just a matter of time?

Mrfix

You're not wasting your money. Even though you only have direct injection the fuel cleaner will help keep your pistons and cylinders clean. A $10 can of Seafoam once a month is hardly wasting your money. If you wait for symptoms to show up then it will be too late for anything but a rebuild.

So if your inclined to try to prevent a problem in the future run the Seafoam through and also follow the directions in the video I posted. When you spray the Seafoam into the intake manifold it cleans your valves that otherwise don't get clean in the normal operation of your vehicle. That's why I posted it. Running it through your intake like in the video is probably the most important thing you can do to avoid the problem.

And fix your PCV system because that is the primary cause of why the carbon issue occurs.

If you can't do that because you don't feel confident then find someone who can do it for you. Or just accept the fact that you might eventually have to spend 3-5 k to fix your car.

The350Girl

It does if you do an Italian Tune after, those thing makes gas burn faster and it gets hotter so it burns down the carbon in your valve stem piston and cylinders, i know you read those posts from here, someone said nothing will help with carbon build up, i've read those couple days ago, one of the Forum Mod keep resisting that anything will help carbon build up on IS250, its just carbon it's not Cancer you be ok if you use Seafoam. Fuel injector and ChrisFix's video way.

You always use Super Premium gas to prevent carbon, you also have to do Italian Tune after you seafoam or fual injector, you can also do walnut blast way but that too much work and not safe if you don't know how to dismantle the engine, Get an oil catch can, buy the oil separate can like Mercedes and BMW has, it helps a ton, go WOT at least 5000RPM after seafoam fuel injector or after filled up gas on Freeway/highway 2-3 times a week.

The way Direct injection engine build for Luxury car is to grab your money from those who don't know, there always a way to fix a problem in any car, you gotta believe, Those who said Carbon on IS250 can't be fixed, they don't know anything about Toyota/Lexus, one of the kid at my friend's shop had an argument about IS250 carbon after i brought my BF IS250 he just shuts !

And BMW/Mercedes do have Oil Separator. You can do that (custom) on IS250 as well.

The350Girl

If you live near me ill show you how to make your IS250 new again, What MRFix said is totally true and will work ! PCV Valve is another thing check out my post above.

sktn77a

iTrader: (2)

What's an "Italian Tune"???

SQLnovice

Thanks MrFix and The350Girl.
I'll continue doing what i'm doing.
I also have been putting RC fuel in my car. A gas station near my house has this fuel which has no ethanol. Is this a good idea? I always use chevron premium fuel in the past.
My car is paid for and has close to 80k miles. It's in excellent condition. Once I get the dash and door panels replaced, it will be like new. I'm hoping to get an additional 200k more.

ajfinoak

Really dodged a bullet on this one. Brought my 2008 Lexus 250 with 54,000 miles in for the misfire test literally the final day day before the nine year warranty for this repair was to end. I would every couple of months or so get the dropped RPM and shaking idle for a few seconds but never had a check engine light. I decided it would be worth it to spend $200 to have the dealer test the car. Turned out that it failed the test and the dealer did the rebuild saving me $6000 per their invoice to Lexus. I would encourage anybody who even think they may have the symptom to go ahead and take the car to the dealer for the misfire test before your nine years is up. I had spoken with Lexus corporate a few days before I brought the car in to discuss that I was having a very intermittent symptoms and they said unless I had a documented failed misfire test the car would likely not be covered even a day after the warranty expired.

Mrfix

That's great. If you're going to keep the car for any length of time, perhaps it would be wise to invest in a "catch can" ?

chriso5573

Here's a DIY I did a while back when I installed my catch can from RR-Racing. It was originally designed for the IS-F and it works great. It filters out quite a bit of blow-by/oil. I've had it installed for about a year now and couldn't be happier. Hope this helps!

https://www.clublexus.com/forums/is-...rator-diy.html