Lexus IS250 4GR-FSE Engine Carbon Build-up (merged threads)
07-02-10, 12:58 PM
#241
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No, I have an 07 ES350 that I've been dealing with this since about 15k miles. I now have 60k on it and I've heard about every excuse from Lexus - I've even written a letter to Lexus Corporate and got no solution back from them or acknowledgment of the problem.
Originally I was told that it was the "winter fuel mix" in the winter of '07/'08" then when winter turned to spring and spring to summer and it didn't go away, then I got the "they all do it". Then I found the TSB for the motor mount in '09 and had high hopes, but that didn't solve it either. Now, the latest thing I heard from a Tech when he was riding with me for the transmission shudder is that the frame of the car twists and causes the engine to vibrate - that was his explanation for the vibration he witnessed - even though the car was stopped on a very flat portion of a major highway. I've been to 3 different dealers in my area and none of them have mentioned anything about this carbon build up issue.
Ultimately, I get the impression that unless something is flat out broke, that Lexus is not going to fix it (unless the gov makes them). Which is terrible, based upon what the Lexus reputation is supposed to stand for. I just think that Lexus is in some major cost cutting mode and doesn't care.
I wasn't aware that this was going on with the IS until today. As a matter of fact, if I listened to the dealers, I would think that I'm the only one having this problem.
I feel sorry for you IS owners as well who are going through this.
Originally I was told that it was the "winter fuel mix" in the winter of '07/'08" then when winter turned to spring and spring to summer and it didn't go away, then I got the "they all do it". Then I found the TSB for the motor mount in '09 and had high hopes, but that didn't solve it either. Now, the latest thing I heard from a Tech when he was riding with me for the transmission shudder is that the frame of the car twists and causes the engine to vibrate - that was his explanation for the vibration he witnessed - even though the car was stopped on a very flat portion of a major highway. I've been to 3 different dealers in my area and none of them have mentioned anything about this carbon build up issue.
Ultimately, I get the impression that unless something is flat out broke, that Lexus is not going to fix it (unless the gov makes them). Which is terrible, based upon what the Lexus reputation is supposed to stand for. I just think that Lexus is in some major cost cutting mode and doesn't care.
I wasn't aware that this was going on with the IS until today. As a matter of fact, if I listened to the dealers, I would think that I'm the only one having this problem.
I feel sorry for you IS owners as well who are going through this.
07-02-10, 02:50 PM
#244
There doesn't seem to be good fix for this, this happens on pretty much all Direct injection cars..
in a few years we probably will see mecahnics offering intake valve scubbing service, that includes removing the intake manifold (hopefully not too much difficult on a V6 than I4) and cleaning the heck out of the valves. The injector tip probably needs to be clean as well.
Perhaps we will see more competitive rates due to the number of cars on the road affected.
Direct injection to meet emission standards? It seems the emission impact from the gunky valves gives you much less clean emission than expected.
in a few years we probably will see mecahnics offering intake valve scubbing service, that includes removing the intake manifold (hopefully not too much difficult on a V6 than I4) and cleaning the heck out of the valves. The injector tip probably needs to be clean as well.
Perhaps we will see more competitive rates due to the number of cars on the road affected.
Direct injection to meet emission standards? It seems the emission impact from the gunky valves gives you much less clean emission than expected.
07-02-10, 03:47 PM
#246
VW assuming we are referring to turbo ones could have a little more oily vapor when pushed hard.
My understanding is that on port injection cars there is fuel to "clean" the values (gasoline is a good degreaser) from accumulating oily vapors, but with direct injection this does not happen and the intake valves get gunked up..
Please explain what is fuel based carbon.. how is the Lexus engine different.
The IS350 seems to be less prone to this because they also have port injection and is engaged during certain driving conditions.
07-02-10, 04:36 PM
#247
You could try this oil (Biosyn 5W-40) - it's development funded by an RS4 owner.
After having the previous valve deposits issues running Audi approved oils, SilverRS4 took matters into his own hands by changing to Biosyn 5W40 and BioPlus, along with pulling the intake manifold to view the intake valves on a regular basis. Here are his results:
I had the manifold off the fourth time about a month ago when there was close to 3000 miles on the Biosyn (. The valves were not clean, but it was more of a thin, oxidized film of oil, rather than thick, gooey, flow-blocking black crud (which was the case after 4000 miles of factory oil, 4000 miles of Mobil 1, and less than 1000 miles of Castrol TXT). I was pleased and will certainly keep using the Biosyn. I am sure Scott could fill you in on the chemistry that makes the build up rate noticably less. I also use the Biosyn fuel conditioner (2 oz) with each fuel fill of Shell gasoline to make sure the injectors stay clean. With the FSI aspect of the 4.2L engine, I believe that sparkly clean valves is just not a realistic expectation - even with Biosyn. But I am happy with how its working thus far. The aspect that really hasn't been discussed is the affect that the oil "contaminated" intake charge has on optimum spark timing. The advanced RS4 ECM's and knock sensors seem particularly sensitive. After endless logging, I have a few cylinders that have timing retarded 4-6 degrees under moderate loads and 9-11 degrees under heavy loads. That is significant. I live in the Midwest and am stuck with Ethanol blended fuel even in the 91-92 octane Tier 1 fuels (Shell included)- that could be part of it, I don't know.
As far as my cleaning method, it was just the old fashion way. In six of the eight cylinders, the intake valves were completely closed, so I just poured in several ounces of carb cleaner right into the intake ports and let the valves soak several hours. Then a majority of the crud comes off with aggressive scraping with an appropriately shaped metal tool. The valve stems block the ability to scrape the area behind them. Vacuum out the mess. Then I poured in fresh solvent and put a small Dremel-type wire brush tool on the end of a cordless drill. Scrub, scrub, scrub. The varnish layer of buildup on the valve surface is very, very hard. This method is limited and removes 90% of the build up at best. The walnut shell blasting would be far better. I have access to such blasting equipment and media, but its ridiculous that I or anyone else has to consider such a chore ...warranty work or not.
As far as my cleaning method, it was just the old fashion way. In six of the eight cylinders, the intake valves were completely closed, so I just poured in several ounces of carb cleaner right into the intake ports and let the valves soak several hours. Then a majority of the crud comes off with aggressive scraping with an appropriately shaped metal tool. The valve stems block the ability to scrape the area behind them. Vacuum out the mess. Then I poured in fresh solvent and put a small Dremel-type wire brush tool on the end of a cordless drill. Scrub, scrub, scrub. The varnish layer of buildup on the valve surface is very, very hard. This method is limited and removes 90% of the build up at best. The walnut shell blasting would be far better. I have access to such blasting equipment and media, but its ridiculous that I or anyone else has to consider such a chore ...warranty work or not.
07-03-10, 05:11 AM
#249
^^^I hate to quote myself, but here is what I posted on #161....
EXCESSIVE CARBON BUILDUP
Some late-model engines can develop carbon problems in less than 10,000 miles, as now seen in the 250 motors. There are 2 kinds of deposits, so lets try and not get them confused.
Oil-based carbon deposits - these are the traditional gummy, black one like those sometimes found on intake valves (like the pictures above). They are caused when oil and heat come together.
Carbonaceous deposits - are from fuel. They are also called "cauliflower deposits" because of their resemblence. These deposits are not as thick as oil deposits and are hard, dry, and tougher to remove. Driveability problems can result from them.
The carbon deposits that are causing driveability issues in our engines are from fuel and not oil. A malfunctioning PCV valve will cause oil-based deposits, which is not our problem. An apparent design flaw has caused the 250 motor to have excessive fuel-based carbon deposits, which I do not know yet. All of our motors will have some sort of fuel-based carbon deposits eventually, and will need to be serviced.
Carbon deposits cause driveability problems because fuel vapors can be absorbed into them. That means some of the fuel never reaches the combustion chamber. This results in rough idling when cold, as well as loss of power, surging, and high emissions. Carbon deposits on valves sometimes cause problems in as little as 5,000 miles.
These carbon deposits can be removed by using an additive such as Top Engine Cleaner, but be aware that carbon removers can damage catalytic converters if used too often.
Hopefully that helps
Some late-model engines can develop carbon problems in less than 10,000 miles, as now seen in the 250 motors. There are 2 kinds of deposits, so lets try and not get them confused.
Oil-based carbon deposits - these are the traditional gummy, black one like those sometimes found on intake valves (like the pictures above). They are caused when oil and heat come together.
Carbonaceous deposits - are from fuel. They are also called "cauliflower deposits" because of their resemblence. These deposits are not as thick as oil deposits and are hard, dry, and tougher to remove. Driveability problems can result from them.
The carbon deposits that are causing driveability issues in our engines are from fuel and not oil. A malfunctioning PCV valve will cause oil-based deposits, which is not our problem. An apparent design flaw has caused the 250 motor to have excessive fuel-based carbon deposits, which I do not know yet. All of our motors will have some sort of fuel-based carbon deposits eventually, and will need to be serviced.
Carbon deposits cause driveability problems because fuel vapors can be absorbed into them. That means some of the fuel never reaches the combustion chamber. This results in rough idling when cold, as well as loss of power, surging, and high emissions. Carbon deposits on valves sometimes cause problems in as little as 5,000 miles.
These carbon deposits can be removed by using an additive such as Top Engine Cleaner, but be aware that carbon removers can damage catalytic converters if used too often.
Hopefully that helps
07-03-10, 08:17 AM
#250
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Lobux -
Can you comment on the impact (or lack thereof) on the use 10% Ethanol gas and this problem on the 2GR/4GR engines? I know that the Ethanol blend sucks and takes 5MPG on my engine but I don't know how it affects carbon build-up.
TIA.
Can you comment on the impact (or lack thereof) on the use 10% Ethanol gas and this problem on the 2GR/4GR engines? I know that the Ethanol blend sucks and takes 5MPG on my engine but I don't know how it affects carbon build-up.
TIA.
07-03-10, 09:43 AM
#251
Only a few solutions exist so far that I have studied.
1.) Water injection will allow minor cleaning (as mentioned earlier, a NA car will see much less performance benefits than a boosted one, but benefits can still be had.
2.) All VAG dealerships are pressing you to use nothing but top tier gas which is costly, but keeps buildup (which still happens) at a slower rate.
3.) Use the BG product (Highly trusted in the performance industry) injected into the intake manifold (Here is a clip of it being done on an Audi). This should become a annual maintenance thing for all DI engine owners.
Personally I feel this problem is big, and I mean REALLY big.... It is going to bite a lot of owners as mileage and performance begin to drop.
I suspect it will bite manufactures a bit, but they are hoping to get you out of warranty before the problem becomes pronounced
As a trained aircraft mechanic, DI is actually old school technology from WWII, but those engines got torn down on a regular basis.
I had though about buying a spare head for the A4, and making a semi-annual swap as part of a routine maintenance. This is the only true fix right now...
Hope I'm not stepping on toes, I only read the first four and last four pages here before posting, but wanted to ad my info for your consideration. Maybe it is old news to you , for which I will apologize.
Vince
