inkaddict

I have a 2009 Lexus IS 250. I got the car around 69,000 miles, about 10 months ago. I noticed the rough idle, especially on cold start. I got the check engine one time at which point I was doing about 70 mph and the car wouldn't accelerate. It felt bogged down and once I slowed down it would accelerate very slowly and only up to about 40 mph, pedal to the floor. Auto zone said it was a misfire code. When I restarted the car, check engine light was gone. The slow acceleration issue never happened again. Talked to dealerships a few times and every time they said I needed a present misfire code and that I needed to pay diagnostic fee. So even though I knew it was the carbon buildup issue, i thought it wasn't worth the hassle. Fast forward a couple months. I was doing the spark plug change on it at 103,000 and when I took the intake manifold off, i could see all the carbon and gunk built up to the point where it was definitely impeding the valves. So I took pictures and called corporate. They told me I didn't need to pay anything and I didn't need a present misfire code. If the car had the issue, they would fix it, which is what I was told. I take it to the dealership, they tried saying that I needed a present misfire code. I told them I don't. I told them let's get corporate on the line and they immediately started testing my car. So I gave them my car and the pictures of the carbon buildup. Sure enough it had the carbon buildup issue and corporate had approved it. I know I'm late in the game, but this was my experience. Hope it helps. All I can say is do not believe a word the dealership says, cross reference everything with corporate. My question that I have is for people who have had the engine rebuild done. I've been told the rebuild included new parts that STOP the carbon buildup. So can i not worry about it at all? I know it's direct injection, which requires higher octane, but can I use something other than premium gas? Possibly midgrade? Is there anything else that you guys ran into after the rebuild? I appreciate all the help. Lexus Fam.

Aspect

No, don't use mid-grade gas... if the engine requires premium 91 then give it 91 and no lower. The engine rebuild that Lexus has done I think changes the piston design. It helps prevent carbon buildup but some owners have gotten carbon buildup even after the "fix". So I don't think you can stop worrying it about it 100%. Best thing to do is run and oil catch can setup and do walnut blasting if you ever see the intake manifold being gunked up to a high degree again(before carbon buildup symptoms occur). After the engine rebuild I'd prob keep an eye on it and check it every 50-60,000 Kms or so.

MikeFig82

iTrader: (13)

Eventually it will happen again maybe in another 100k miles. It's a direct injection engine. I don't think there's much you can do to prevent it. Maybe add a oil catch can? As for gas you don't want to go below recommended manufacturers octane grade. It sucks as one day I will experience the same. There was a member who's successfully cleaned his valves recently with Berryman B12 cleaner, and some elbow grease. They looked spotless after he was done. You can look into maybe doing it yourself in the future if it comes to it.

DixieLex

1) Don't run lower octane...
2) DO use a lower NOACK oil (less volatility)...yes this is important. Pennzoil Plat, Redline, Amsoil, many 10w30's have low volatility
3) Install an oil catch can, it'll help
4) Use top tier gas, it helps w/FI and keeps the rest of the fuel system clean
5) Change the oil about 5-7K, don't prolong OCI's
6) Italian Tune about 1-2x per month.
7) Take it out on a long excursions, where it stays at WOT for long periods of time
8) Look at EGR and crank case ventilation, consider replacing if its fowled w/soot
9) Don't worry, enjoy your car
10) If all fails, have it walnut blasted and drive for another set of miles

heliskiier

What's the problem with less than 91 gas? Every ECM car out there auto adjusts timing, spark, ignition, etc for less than 91 grade. Heck, my turbo 9-3 makes the turbo and timing curve adjustments in it's sleep. You don't even have to think about it. You will lose some HP/TQ. Not a big deal when you have 300+ under the hood and can just switch back up when you want. Unless, the IS is unlike every other ECM car ever made...U can keep the injection clean very inexpensively. Take it from a guy with a 430HP 2002 SS camaro with mild cam, all bolt ons and a custom ECM tune map. They all run fine and U can't hurt them with 87/89. U can hurt them with lame gas of any type though.

DixieLex

and his issue is CBU. It really doesn't make sense to use less octane. 1) no proof lower octane prevents CBC
2) worse MPG
3) less power
IS needs all the power it can muster
4) alot higher octane fuels have a much better additive pkg.

604GSE21

isn't almos all 91 and above gas nowadays don't have ethanol which is better for the engine?

DixieLex

I'd like to see 100% gas' effect on DI engines over the long term. I just put 93 octane ethanol free in my IS250 Monday.
SLIGHTLY better MPG, butt dyno...about the same. It can't have a deleterious effect on the engine but is it worth over the price of higher octane with ethanol.

DixieLex

[QUOTE=604GSE21;9893872]isn't almos all 91 and above gas nowadays don't have ethanol which is better for the engine?[/

ethanol does not hurt newer 4 stroke engines. 70's and 80's cars...straight gas

I use straight gas in my mower and other 2 strokes

604GSE21

[QUOTE=DixieLex;9893972]i see...

Andysavage

how do i get in contact with corporate? i also have a cylinder 3 misfire code and dirty intake, along with spark plugs. im hoping to get the work done without paying first for diagnostics at lexus

inkaddict

Call there phone number +1 800-255-3987. I didn't pay any diagnostics fee. That was my issue and why before even going in I knew what the standards were from corporate. There does need to be evidence of the carbon but from what your saying it's way past the point that mine was, so you should be fine. Just talk to corporate.

RussZTT

You can run lower octane. Gas now, the lower octane is required to have the same cleaning solution that is in the higher octane fuel. Like it was mentioned above, the ECU will do its job about lowering the timing if needed. Plus these motors are pretty low compression.

jr4div2

I would love to see your reference on your advice since you say that Lexus still required Premium gas in, I know, 2012 (I have a 2012) and the fact that the ECU will "do its job" to adjust. Show me where Lexus says that please.

heliskiier

Almost every auto maker on the planet recommends 93 octane, or says requires. Not because it can be a problem for the car running 87, but because the ECU will adjust the timing etc to 87 and produce less performance, which to auto makers means that their/your car doesn't perform like they say it will. I can live with 10-20 less HP most of the time and save 30-50 cents a gallon (or a bit over $15 bucks a fillup). I can always fill up with 93 when I feel like it or, just pop a bottle of octane boost in for way cheaper. The ECU will adjust back very quickly and your on fire again. There are absolutely no harmful effects to any OBDII motor of putting in regular. Look it up. Google it. Research it.