I thought this was a decent read that all of us Lexus LS owners may enjoy, especially since its a known, spoken about topic amidst this LS 460 forum. No mention of Lexus, even though it does mention that DI typically is an engineering variable that has been present in luxury vehicles. Thus far, it seems as though Lexus has this point of engineering very well understood and implemented.

Enjoy!

https://autos.yahoo.com/news/direct-...193000698.html

 

Nice article and I have heard of the walnut shell cleaning method, snap on sells a tool that once the manifold is removed, allows a tube to be placed down by the intake valve where it sprays the shells agains the valve, freeing up carbon deposits. I've seen pictures of BMW intake valves and let me tell you....this is a big problem. A problem that our car does not have due to the port injectors above the intake valve. Also, you should hear some of these direct injection engines, some of them sound like cement mixers. Yeah ours is a little noisy, but it's quiet compared to some I've heard. I've sat in an Audi once and thought...there's no way I could on this car, this is embarrassing.

 

The LS used dual fuel injection - both direct and port injection. So it probably won't have the same issues as the IS250 which has direct injection only.

"It's interesting to note that the 2.5L V6 in the Lexus IS250 (a direct injection engine) is experiencing severe carbon build-ups like everyone else. (Lexus extended the warranty on these cars and is offering free top engine cleans to address the problem.) However the same car is also available with a 3.5L V6 (the IS350) that uses two injectors per cylinder--one is direct injection and the other is standard port injection. These cars are *not* experiencing the typical direct injected carbon build up and all the forums keep pointing at the Lexus 2GR-FSE engine design as the solution to the problem.

"The 2GR-FSE employs what may be described as "hybrid direct-injection, port-injection strategy," the only known such system among volume production engines in the "emission control zone," according to Shizuo Abe, Toyota's product General Manager. He cites a sample operating condition at 1200 rpm with a 60% load ratio: with direct-injection alone, fuel tends to form in lumps due to heavier fuel volume and slow piston speed, lengthening combustion duration, and thus limiting torque output. On the other hand, port-injection alone would not necessarily be better. Adding 30 to 40% direct-injection to port-injection accelerates gas flow, significantly improves torque output. Injection ratio between the two injectors is continuously varied?for example 30 to 40% in a specific parameter, and increased to 50 to 60% in another zone?optimizing the mix and distribution. Ultimately in high-rpm zone, 100-percent direct-injection is used to obtain higher torque." Toyota has 300 patents on this system.

It appears that fuel flowing around the valves is necessary to prevent the carbon build up. I'm really happy we found a new car without direct injection, but it looks like Toyota was the first to implement a way to prevent the problem. It will be interesting to see if the other auto manufacturers do the same. "

 

I think it's safe to say that our cars are not effected by this problem because of the port injection system our cars also have. It really can't be stated enough how much fuel being sprayed onto valves cleans carbon. And for all of the people that buy "fuel injector cleaner", do yourself a favor and stop wasting your money. I've taken hundreds of engines apart and believe me the cleanest part of those engines were the injectors...fuel has detergents in it and it is always cleaning those injectors.

 

A cement mixer! Lord have mercy!!
Walnut shells huh..?? I mean, the abrasion aspect makes sense, but for me, I had never heard of such a procedure, and was definitely not aware that a carbon build up issue could be that serious!

 

This brings back nightmares. My 7 series had this carbon issue in the heads. So did 90% of the other forum members at Bimmerfest.com The result was a 5-7k dollar job to repair - a repair that was temporary, as the problem would eventually come back. The actual issue did not cause mecanical or driveability issues, but unfortunately, would set of the SES light and a as a result, you could not pass emissions testing. The problem is so prevelant, that a company/shop in LA that specializes in BMW repairs, invented a tool set that unclogs these passages adn is making a mint.

 

Ok...let me say this as a pre courser:
I am not well versed regarding vehicle mechanics, as I am learning many things...nor am I familiar with business practices as it involves companies that manufacture a product such as a car with known issues, but wont properly address them.

On to my question.
Taking what you just said Roadfrog, and internalizing it makes absolutely no sense to me. I don't understand why something of this magnitude, that is a recognized problem amidst many, many owners, goes unadressed by the manufacturer? Would I be so ignorant to make a statement in saying: Is it really all about the money?

 

This is why when Lexus does a recall, I'm esctatic. BMW had NO recalls on this issue, or the even more dire one where the valve stem seals were faulty and caused severe oil-burning (in my case at 50k miles)....blue smoke everywhere. What they did in that case was do an update TSIB on replacing the seals with Viton seals.....but still on the onus of the owner to the tune of 7-12k dollars. Once again, All German Auto in LA decveloped a kit to lower the cost to a manageable 2-4k dollars which allows the seals to be installed without removing the heads. Again, not a one-off problem....many owners had this issue and contributed to accelerated carboning of the heads.

Then there's the coolant pipe issue. A pipe buried in the motor that carries coolant and had seals that would deteriorate around the 50-60k mile mark, which required removing the intake manifold, fuel system, etc (to another tune of 4-7k dollars), to replace a 50 dollar part. AGAIN, All German Auto developed another kit for 200 dollars that turned that job into a 1500 dollar repair. I had ALL these issues as did most others at Bimmerfest. And remember.....we're talking about a 7 series - the flagship of BMW!

Google, All German Auto (AGA) or BMW oil burning, coolant pipe, carbon etc, and enjoy the reads!

"Hey Lexus!"......got any other recalls you'd like to hook me up with? I'm your fella!"

 

I was wondering how much the valve cleaning repair costs, is it really that much?

I watched a video on it the other day and they said the service generally needs to be done every 30-35k miles!! Believe that? I guess that makes sense.

I figure on the straight six, it takes 2 hours labor to remove the intake and expose the valves. Then you have to bump the engine to get the intake valves closed. The cleaning procedure for a six cylinder must be around an hour...maybe more with machine setup and removal of the walnut shells. You would need an intake gasket set and the throttle body set. They probably would charge you somewhere around $100 for the walnut shells.

I'd think a local (non dealer) shop would charge $300.00 - $500.00 labor, $200 for the gasket set and maybe $100 for the walnuts, for a total of $700-$800....give or take a hundred. I realize this figure is probably low even for a local shop, but could you imagine paying $800 every 30k for this? I'd have to do it every year.....with the LS all I usually have to worry about after 30k of driving is to replace the air filters.

I have a friend that owns a German repair facility and he doesn't have the walnut blasting machine, he uses a small wire brush, some picks and a shop vac...says it's a real pain to do. I don't know what he charges for it, but the guy is always busy because the German cars keep finding new and exciting ways to build a terrible car. Audi is his specialty. I've been to Audi training and they actually brag that if you beat on their car and drive it harshly, you won't get the carbon buildup problems as much. Believe that?