Lexus IS250 4GR-FSE Engine Carbon Build-up (merged threads)
06-10-10, 12:18 PM
#151
My 08' IS250 has 44,000 miles on it right now. Every since I had the car it would "stutter" maybe once every 4 months. Recently it's been "stuttering" once a week now. Usually it would stutter a bit and go back to normal but on one occasion the VSC light came on and it wouldn't go above 2000 rpm ot 30 mph. Lucky I wasn't on the freeway. I had to restart the car to get it back to normal. I'm going to have the dealership perform the TSIB on my next oil change.
This is really making me question the reliability of this car. This is my daily driver and I plan to keep it for 5+ years. I drive about 22k miles per year and reliability is critical. This seems to be a recurring problem with no real long term fix. Should I be worried when the car hits 80k, 100k, 120k miles?
This is really making me question the reliability of this car. This is my daily driver and I plan to keep it for 5+ years. I drive about 22k miles per year and reliability is critical. This seems to be a recurring problem with no real long term fix. Should I be worried when the car hits 80k, 100k, 120k miles?
06-10-10, 12:34 PM
#153
Lexus Fanatic
I guess they aren't expecting customers like me when they give that excuse, since I have written records for all my gas purchases since day 1 (via a Chervon card, which is the only way I purchase gasoline).
06-10-10, 01:51 PM
#155
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06-10-10, 04:25 PM
#156
i called corporate tonight and asked what their plan is about this problem. we shall see who contacts me to talk more. i know they will be talking to my dealership. what a pain!!!
06-11-10, 05:52 PM
#158
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06-15-10, 11:52 AM
#159
Thoughts about Carbon Buildup in our engines
It seems like an accumulation of carbon buildup on valves is the cause of a one time, intermittent stumble at idle when coming to a stop. Some people have blamed the PCV valve as the source of the carbon, as it is in the VW turbocharged engines which tend to consume half to a full quart of oil between changes.
Here are a few of my thoughts... I hope this kicks off a technical discussion we can all learn from
1) The top end cleaning TSIB has a VIN production range stated. This implies some IS250s, presumably produced late in the 2010 MY run do not qualify and would not suffer from this problem. This leads me to wonder, what change could have been made?
2) If the obstruction was significant enough to disrupt the engine idle, how could it occur just once when say, coming off of a highway? Once you come to a stop from high speed operation, the RPMs dip into the 400-500s for a second and everything is back to normal. Wouldn't an obstructed inlet cause a perpetual bad idle or repeated misfire on that cylinder?
3) Toyota has been using direct injection for 10 years. The possibility of buildup on valves was surely understood by engineers and IMO deemed not a significant problem. Intakes and valves have been getting dirty for years.
4) IS350 engines with dual injection apparently have issues with carbon buildup as well.
5) Our engines don't seem to consume a measurable amount of engine oil. In the case of the VW, a steady trickle of oil passes through the PCV valve, and the PCV hoses are an oily mess. I don't believe we have this problem.
6) Some users have noticed this issue with very low mileage (less than 10,000 miles). Is that enough time to have a carbon buildup problem, when a VW that passes ounces of oil through the intake doesn't usually develop any kind of issue until thousands of miles later (and the valves are really coked up)? I don't think so.
I think the engine tune and programming is causing this problem. Some engines are programmed to deactivate the fuel injectors on deceleration -- if our engine does this, perhaps they are not kicking back in fast enough. Also, the engine may benefit from running leaner. It may also benefit from a higher engine idle speed - most of us have noted a smoother idle when the a/c or lights are on.
If these things can be adjusted with software, it may be included in the new engine software that includes brake override. This may explain why there is a VIN range -- the brake override is included on new 2010 cars.
OK, lets discuss
Here are a few of my thoughts... I hope this kicks off a technical discussion we can all learn from
1) The top end cleaning TSIB has a VIN production range stated. This implies some IS250s, presumably produced late in the 2010 MY run do not qualify and would not suffer from this problem. This leads me to wonder, what change could have been made?
2) If the obstruction was significant enough to disrupt the engine idle, how could it occur just once when say, coming off of a highway? Once you come to a stop from high speed operation, the RPMs dip into the 400-500s for a second and everything is back to normal. Wouldn't an obstructed inlet cause a perpetual bad idle or repeated misfire on that cylinder?
3) Toyota has been using direct injection for 10 years. The possibility of buildup on valves was surely understood by engineers and IMO deemed not a significant problem. Intakes and valves have been getting dirty for years.
4) IS350 engines with dual injection apparently have issues with carbon buildup as well.
5) Our engines don't seem to consume a measurable amount of engine oil. In the case of the VW, a steady trickle of oil passes through the PCV valve, and the PCV hoses are an oily mess. I don't believe we have this problem.
6) Some users have noticed this issue with very low mileage (less than 10,000 miles). Is that enough time to have a carbon buildup problem, when a VW that passes ounces of oil through the intake doesn't usually develop any kind of issue until thousands of miles later (and the valves are really coked up)? I don't think so.
I think the engine tune and programming is causing this problem. Some engines are programmed to deactivate the fuel injectors on deceleration -- if our engine does this, perhaps they are not kicking back in fast enough. Also, the engine may benefit from running leaner. It may also benefit from a higher engine idle speed - most of us have noted a smoother idle when the a/c or lights are on.
If these things can be adjusted with software, it may be included in the new engine software that includes brake override. This may explain why there is a VIN range -- the brake override is included on new 2010 cars.
OK, lets discuss
Last edited by hades281; 06-15-10 at 11:57 AM.
06-15-10, 11:59 AM
#160
Lexus Fanatic
about the engine running leaner: well the 250 have a 12:1 compression ratio so running leaner~ would cause higher engine temps among other things~ n higher temps = bad... so if running leaner in a F1 car is bad, it must be bad for normal cars too right? 
*yes im comparing our cars to F1 cars
*
*yes im comparing our cars to F1 cars
*
06-15-10, 01:45 PM
#162
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so your saying that not all is250 suffer from carbon builtup cause i dont have any problem like that yet and my is rwd is250 24k in it and i look up the tsib my vin is not in there.
06-15-10, 02:55 PM
#163
The carbon build up is caused by the fuel being induced directly into the cylinder instead of through the intake track across the intake valves. Combustion by-products (carbon) accumulate on the intake valves and the additives/detergents in the fuel do not flow across the intake valves to help keep the valves clean.
Last edited by Koz; 06-24-10 at 04:40 AM.
06-15-10, 03:27 PM
#165
No, I have 40K miles and all is well. I don't think the 350 will suffer as bad as the 250 because the 350 has port and direct injection. I also only use "Top Tier" fuel and I'm at WOT every time I drive my car!
The picture with the valves in head is a direct injected RS4. Owners are very upset and several are dumping them ASAP.
Koz
The picture with the valves in head is a direct injected RS4. Owners are very upset and several are dumping them ASAP.
Koz