Lexus IS250 4GR-FSE Engine Carbon Build-up (merged threads)
05-11-12, 01:10 PM
#916
I never got the TSIB done because my car never registered any misfire codes. So even taking it to the dealer prior to hitting the 70k mark and telling them how I experienced the symptoms of carbon build-up, that was not enough to justify them performing it for me. Now that I'm over 80k, I'm assuming dealers won't cover it under the powertrain warranty. Would WOT-ing it at least once a week prevent the buildup, or is that just a temporary solution?
05-11-12, 01:32 PM
#917
uh..., what?
the carbon issue is on the intake valves.
Which are cleaned by fuel in non-DI engines.
And also in the IS350 that has port injectors.
That's why it is not an issue at all on the 350, but is a common one on the 250.
The cylinders aren't the part that need washing (and if they were the 250 wouldn't have a problem since fuel DOES go there) and it's not like non-DI combustion chambers don't get hot either so the temps are irrelevant.
it's the valves.
Which are kept clean by the port injectors on the 350. Hence why, again, 350s don't have the issue.
the carbon issue is on the intake valves.
Which are cleaned by fuel in non-DI engines.
And also in the IS350 that has port injectors.
That's why it is not an issue at all on the 350, but is a common one on the 250.
The cylinders aren't the part that need washing (and if they were the 250 wouldn't have a problem since fuel DOES go there) and it's not like non-DI combustion chambers don't get hot either so the temps are irrelevant.
it's the valves.
Which are kept clean by the port injectors on the 350. Hence why, again, 350s don't have the issue.
05-11-12, 03:18 PM
#918
Correct.
Since it does have them it doesn't experience this problem at all.
It operates some of the time during use, but every time you use the car.
The port injectors don't fire off during wide open throttle, but may be firing nearly anytime else depending on driving conditions.
As Lexus describes it- The simultaneous injection during warmup and at certain load points allows improved combustion stability
So as the engine is warming up, every time, they are firing. Which cleans off anything on the valves since the last time. And at some other times as well.
Thus the car never gets time to build anything up on the valves more than maybe a couple hours at a time, which is then cleaned off the next time you drive the car.
If they didn't operate for months at a time, sure. Not minutes or hours though.
This isn't specifically a 4GR problem. It's not even a Lexus problem. VW, Audi, Mercedes, BMW, Hyundai, Caddy, and more have all seen these issues in one form or another.
Newer DI only motors are using tigher ring/piston tolerances, intake-cam timing, injector targeting and timing of the injection events and other methods to try and reduce the problem (Lexus changed the rings/pistons on the 4GR sometime during 2010 or 2011 production, don't recall which, and they're now replacing rings/pistons on older cars that complain about it)... but it's somewhat inherent to the design of DI only.
As second and third gen DI motors come out you'll see it take a lot longer for it to show up, and they'll probably start adding something like "perform top engine clean" to the scheduled service every X miles or whatever to deal with it. (ideally something like every 60k if the other improvements reduce occurrence enough, so that most owners won't ever do it but once or twice in the time they own the car, and it's only a few hundred bucks).
05-15-12, 05:28 AM
#920
Well only 1500 miles after Lexus' supposed fix to this problems with the pistons and valves my car shook again this morning when I came to a stop. You've got to be kidding me! NOT HAPPY!!!!!
05-15-12, 06:11 AM
#922
yes zen, i saw you also have had problems again. i will be very disappointed if lexus doesn't do something about this since it's obviouslt a design flaw.
05-15-12, 06:20 AM
#923
Driver School Candidate
i have the same problem. i have 2008 lexus is250 40,000 miles. i bought this car brand new. i've been babied this car, i always put 91 chevron and used mobile 1 synthetic oil good for 15,000 miles. since day one. i always change my oil every 5,000 miles. i only drove this car from house to work. i've been noticed my engine stalling, rough and it almost died. i went to dealership 2 weeks ago, i've been explain with them what's going on. they check everything it's all fine, nothings wrong on it. they always say, they want to replica what's going on. then this week, i was at parking lot, i felt shaking, almost died. i went back to my dealership. now they called me. they told me that they found out some code pop up, carbon build-up. now they keeping my car 1 week, to change my piston. the only good here, it's covered my warranty. but my worry, if they change my piston, is it shortened my engine life? if they gonna change my piston. do i need to get extended warranty is that good or bad? because i wanna keep this car.
FYI : sometimes you need to drive you're car aggressively. not like granny.
FYI : sometimes you need to drive you're car aggressively. not like granny.
Last edited by mojeko; 05-15-12 at 06:41 AM.
05-15-12, 06:47 AM
#924
i have the same problem. i have 2008 lexus is250 40,000 miles. i bought this car brand new. i've been babied this car, i always put 91 chevron and used mobile 1 synthetic oil good for 15,000 miles. since day one. i always change my oil every 5,000 miles. i only drove this car from house to work. i've been noticed my engine stalling, rough and it almost died my engine. i went to dealership 2 weeks ago, i've been explain with them what's going on. they check everything it's all fine, nothings wrong on it. they always say, they want to replica what's going on. then this week, i was at parking lot, i felt shaking, almost died. i went back to my dealership. now they called me. they told me that the found it some code pop up, carbon build-up. now they keeping my car 1 week, to change my piston. the only good here, it's covered my warranty. but my worry, if they change my piston, is it shortened my engine life? if they gonna change my piston. do i need to get extended warranty is that good or bad? because i wanna keep this car.
FYI : sometimes you need to drive aggressively. not like granny.
FYI : sometimes you need to drive aggressively. not like granny.
I do not think the new pistons would shorten engine life since these are used on new model IS250. it's good to get extended warranty on the car since it can also cover other electrical problems if it occurs. The IS250's carbon buildup issue is inevitable. I wouldn't put more money into a car that has known issues for carbon buildup in the long run.
Also, I don't think drive aggressively or do WOT once in a while can prevent the buildup issue.
05-15-12, 07:55 AM
#925
Driver
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man, my car shudders at idle and cranks upon cold start up. I need to get my a$$ to the dealership to get these fixed, might as well grab some spark plugs for them to throw in since they'll be in there (54k miles)
05-15-12, 01:20 PM
#927
So...I haven't even put on 1k miles yet, and while I was waiting at a traffic light yesterday the car was shuddering the whole time. Then there was a loud knocking which went away before i could pull over 
The loud knock had happened the couple days prior too.
Nothings been happening today, but it was pretty upsetting to see the issue come back so early. I'm gonna take it back to the dealer and let them check it out.
The loud knock had happened the couple days prior too. Nothings been happening today, but it was pretty upsetting to see the issue come back so early. I'm gonna take it back to the dealer and let them check it out.
Last edited by KillaIS250; 05-15-12 at 01:36 PM.
05-16-12, 05:41 AM
#930
So...I haven't even put on 1k miles yet, and while I was waiting at a traffic light yesterday the car was shuddering the whole time. Then there was a loud knocking which went away before i could pull over The loud knock had happened the couple days prior too.
Nothings been happening today, but it was pretty upsetting to see the issue come back so early. I'm gonna take it back to the dealer and let them check it out.
The loud knock had happened the couple days prior too. Nothings been happening today, but it was pretty upsetting to see the issue come back so early. I'm gonna take it back to the dealer and let them check it out.