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My daughter owns a 2012 Lexus IS250 that is now at 90K miles. She has had it regularly maintained at the local Lexus dealership. Lately, the car has sometimes rough idle when stopped at traffic light and its gas mileage has also gone down. During the past couple of gas refills, fuel system cleaner additives were used hoping to clean out any gunk in the system. What diagnostic steps should I take to help restore the car's performance?
Thank you.
That thread seems to be all about Gen 1 IS250. Ours is 2012 and we haven't received any "IS250 Carbon Build up CSP" letter. Is this applicable to 2012 IS250 as well?
I see; it doesn't seem to apply to 2011 or newer. Gen 2 is from 2006 to 2013. Maybe your car doesn't have the build up issue though it seems like it does; tried to see if there are any codes to read. Since the car has always been dealer maintained, ask them if they can do a free diagnosis.
The carbon builup is a side "benefit" of the direct injection engine. While the new pistons/rings of the updated cars and later model years helps, it doesn't get rid of the problem. Pretty much all IS250s will have this issue eventually.
I see; it doesn't seem to apply to 2011 or newer. Gen 2 is from 2006 to 2013. Maybe your car doesn't have the build up issue though it seems like it does; tried to see if there are any codes to read. Since the car has always been dealer maintained, ask them if they can do a free diagnosis.
There hasn't been any visual indicator of the engine throwing codes, It's a good suggestion and she'll ask the dealer at next visit.
Telling us Specifically how it is used will define the probability of carbon no carbon.
If it makes two highway passes of 20miles each direction we look in different places than if it keeps them warm/cool at lunch time idling for 30 minutes, runs multiple 3 minute trips, then back to school 5 minutes away, and another start to go home.
How they are used matters in relation to *most* carbon build up stories.
The least you could do is inspect the air filter but more importantly clean the MAF sensor and see when it had new plugs installed last.
Telling us Specifically how it is used will define the probability of carbon no carbon.
If it makes two highway passes of 20miles each direction we look in different places than if it keeps them warm/cool at lunch time idling for 30 minutes, runs multiple 3 minute trips, then back to school 5 minutes away, and another start to go home. How they are used matters in relation to *most* carbon build up stories.
The car is driven 2-3 days of week 36 miles each way mostly (90%) on the highway but sometimes these SF bay Area highways move slow during rush hours. The other 2-3 days, it is driven less than 10 miles each way.
Originally Posted by 2013FSport
The least you could do is inspect the air filter but more importantly clean the MAF sensor and see when it had new plugs installed last.
The air filter is replaced every 6 months. I will clean the MAF sensor next week when I visit her. Lexus dealership has not yet recommended spark plug changes so those are the original ones. Should we replace these anyway?
When I changed my spark plugs at 70K, it still looks good and I'm guessing it can last to 90K or more. I'm not sure if the spark plugs would cause a problem like this but doesn't hurt to change them. The spark plugs on the 250 are hard to change if you're trying to do it yourself (there is a DIY).
JM2C but its about putting eyes on stuff to see change or differences. Are all of holes burning the same and are they clean. If one hole is not like the others then we need to find out why.
Does the car get supereme gasoline 91/93 octane?
Have you ran fuel system cleaner in it?
Does it ever get opened up completely to pull a long hill. Sometimes working those upper RPMs under load blows carbon and debris off from o2 sensors and they run better. Worth a shot outside the city...
JM2C but its about putting eyes on stuff to see change or differences. Are all of holes burning the same and are they clean. If one hole is not like the others then we need to find out why.
Does the car get supereme gasoline 91/93 octane?
Yes, always.
Originally Posted by 2013FSport
Have you ran fuel system cleaner in it?
Been doing it since the last 3 fillups. Some improvement in response is observed.
Originally Posted by 2013FSport
Does it ever get opened up completely to pull a long hill. Sometimes working those upper RPMs under load blows carbon and debris off from o2 sensors and they run better. Worth a shot outside the city...
Start trying this from the start of next week on longer drives.
My daughter owns a 2012 Lexus IS250 that is now at 90K miles. She has had it regularly maintained at the local Lexus dealership. Lately, the car has sometimes rough idle when stopped at traffic light and its gas mileage has also gone down. During the past couple of gas refills, fuel system cleaner additives were used hoping to clean out any gunk in the system. What diagnostic steps should I take to help restore the car's performance?
To the original poster, would you please keep us updated on what the final diagnosis/solution will be once you find out? I think those of us with 2011-2013 IS250s are curious to know whether this is carbon build up or something else. Much appreciated!!
At 90k thats close enough that putting eyes on the plugs tells us a little about its health.
That and clean the MAF.
No codes thrown, correct?
If you have the work done, ask to keep the numbered plugs and take a good shot like this. We want to see the firing end of the plug and where it came from.
06-05-19, 09:19 PM
Stalling and lower gas mileage
