Dec 16, 2014, 12:59 PM
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IS250 Engine misfire-explained
I had this TSB done one my car....hasn't run the same since, avg mpg's dropped by at least 4mpg and I do the same driving....I know other factors might be an issue, but it ran better before overall. I would have never had it done not worth it.
Advanced
Joined: Mar 2011
Posts: 598
Likes: 1
From: Kuwait
Horror of horrors
I just realized my 2010 IS 300 ( 37,000 Km's ) has the 3 GR- FE engine and like the IS 250 most of you guys have here does not have a D4 - S 
.
Which probably means after a few 1000 Km's I too will have the carbon build up problem. Is there anything we can do to avoid it. I was really hoping to take this baby with me back to my homeland. But if issues are going to crop up I would have to sell her
.Which probably means after a few 1000 Km's I too will have the carbon build up problem. Is there anything we can do to avoid it. I was really hoping to take this baby with me back to my homeland. But if issues are going to crop up I would have to sell her
Last edited by stanjohn12; Jun 4, 2012 at 12:10 PM.
I just realized my 2010 IS 300 ( 37,000 Km's ) has the 3 GR- FE engine and like the IS 250 most of you guys have here does not have a D4 - S .
Which probably means after a few 1000 Km's I too will have the carbon build up problem. Is there anything we can do to avoid it. I was really hoping to take this baby with me back to my homeland. But if issues are going to crop up I would have to sell her
.Which probably means after a few 1000 Km's I too will have the carbon build up problem. Is there anything we can do to avoid it. I was really hoping to take this baby with me back to my homeland. But if issues are going to crop up I would have to sell her
The 350 doesn't suffer because it uses port and direct both.
The 250 does because it uses DI only.
The 3GR-FE doesn't use direct injection at all so it doesn't have this issue.
(the 3GR-FSE probably does, but was used in very few applications from what I can tell)
Advanced
Joined: Mar 2011
Posts: 598
Likes: 1
From: Kuwait
I'm so happy. Now I can keep my baby forever. 
Solotex55 since the new rings are the same as the ones in the newer IS250 which use 0w20 oil and extended drain intervals, could you be safe in using the lighter weight oil now that there are new rings installed or are there other factors that are considered?
i had my piston and rings replaced last year but took a lot of work between calling corp office to only have them tell me nothing can be done but after speaking to them several times and stating im not making this up they said they were able to "take photo's and saw there was a bunch of build up" only problem i have is what do i do when this comes back and nothing is covered.......
Driver School Candidate
Joined: Sep 2012
Posts: 25
Likes: 3
From: CA
Hi guys and gals, I am a Lexus Senior Certified tech at a large Lexus dealership. In reading some of the posts here, I see alot of confusion about this subject. You seem to know about carbon build-up, but not the how or why and most important...the fix or prevention.
First, how and why...the misfire is caused when carbon that has built-up on the intake valve flakes off and becomes stuck between the valve and the seat causing loss of compression. This can last from a few seconds to minutes. It does not damage the engine, but can set a Check Engine light if it lasts long enough. The carbon is caused by crankcase blow-by...oil getting in the intake system. With a Direct Injection engine there is no fuel flow over the valve to clean it. The fix is to reduce blow-by...after you clean-up the valves. Lexus has another TSIB out for this. I believe it is L-SB-0048-11. It involes replacing ALL the pistons and rings,also cleaning the valves and replacing the valve stem seals. I personally have done 4 of these. It is most common around 60k miles, but have seen it as low as 29k. It is fully covered under 6/70 powertrain warranty. Now about prevention....I don't know of any. Why do some cars do it at 30k and others have 100k w/o a problem??? Synthetic oil may help, but not enough data to be sure. Good, clean oil can't hurt. The 350 and V-8 models do not have this problem. If you have any questions I will try to answer them as best I can.
First, how and why...the misfire is caused when carbon that has built-up on the intake valve flakes off and becomes stuck between the valve and the seat causing loss of compression. This can last from a few seconds to minutes. It does not damage the engine, but can set a Check Engine light if it lasts long enough. The carbon is caused by crankcase blow-by...oil getting in the intake system. With a Direct Injection engine there is no fuel flow over the valve to clean it. The fix is to reduce blow-by...after you clean-up the valves. Lexus has another TSIB out for this. I believe it is L-SB-0048-11. It involes replacing ALL the pistons and rings,also cleaning the valves and replacing the valve stem seals. I personally have done 4 of these. It is most common around 60k miles, but have seen it as low as 29k. It is fully covered under 6/70 powertrain warranty. Now about prevention....I don't know of any. Why do some cars do it at 30k and others have 100k w/o a problem??? Synthetic oil may help, but not enough data to be sure. Good, clean oil can't hurt. The 350 and V-8 models do not have this problem. If you have any questions I will try to answer them as best I can.
I dropped my car off at Lexus dealership about a month ago and the car is not even done. My car only have 31k miles on it, it's a 2008 is250. My service rep is really nice . He walked me through the working area and had of the mechanic working on my car explain the problem to me. I'm not a mechanic guy so didn't really understand much. Looking at my car I couldn't believe my eyes. They took everything apart. Inside the engine bay is emptied. Mechanic said he had to replace something in the pistons or valve rings. They did all that and the problem didn't go away so now they going to replace short engine block. My rep said its like getting a new engine. I don't need a new engine I just need my car to run the way it should. Hopefully when I get the car back it will be better. After seeing it been stripped apart I don't know if it will run better. I'm just crossing my fingers.
Driver School Candidate
Joined: Sep 2012
Posts: 25
Likes: 3
From: CA
If Lexus is giving you a BRAND NEW short block (short block = bottom end) you should be happy! I've been harping on the so-called carbon build-up "repair" Lexus does; replacing pistons/rings/valves is good and all for a short-fix; but if they were not the original components to the motor they will not work 100% perfectly and will decrease the life expectancy of the motor in my mind. If they were to "fix" it properly, the short block AND the heads would be sent off to a machine shop for a new 3-angle valve job to match the new valves. The block would be re-honed or bored to match the new pistons. But of course, they don't go into that much detail as 99% of folks don't know the difference between a connecting rod and a crankshaft. LOL!
If Lexus is giving you a BRAND NEW short block (short block = bottom end) you should be happy! I've been harping on the so-called carbon build-up "repair" Lexus does; replacing pistons/rings/valves is good and all for a short-fix; but if they were not the original components to the motor they will not work 100% perfectly and will decrease the life expectancy of the motor in my mind. If they were to "fix" it properly, the short block AND the heads would be sent off to a machine shop for a new 3-angle valve job to match the new valves. The block would be re-honed or bored to match the new pistons. But of course, they don't go into that much detail as 99% of folks don't know the difference between a connecting rod and a crankshaft. LOL!