Oh.. Too bad about your IS.. Some dill wad totalled my Pontiac GTO (late model).. I'm happy with the GS 350 replacement.
Ok.. So there's alot to consider here.. Engine temperature.. Where is the temp? Should be about halfway up the guage. How did you clean the MAF and Throttle body? This should be two different processes with two different chemicals. How much oil is the engine using? If you have a strong sulfur smell and you are suggesting bad cats, its likely to throw a code or a few.
No codes mean there could be a fuel issue, running rich. I think at this point your best option is to take it to a dealer that can hook up Techstream and do an entire "Health Check", this will help eliminate the simple issues first. Its comprehensive and will check any function of the engine. Also Techstream can read stored codes that my have been there prior you purchasing the vehicle. Outside of Techstream its a best guess senario due to the fact that so much was done in a short amount of time and close intervals. The RPM flucuation is typically fuel delivery (rich or lean) problem in closed loop or open loop. Another guess would be bad injector(s), but again Techstream would tell you that. Have you disconnected the battery for 10 min.?

 

Hi all,

When I use S mode instead of auto shifting, whenever I down shifting to a stop, the 3rd gear seems very rough (even though the car is already moving very slow or at low rpm). However, when I use automatic, there is no problem at all (down shifting very smooth; I don't even feel like the car down shifting at all). I am curious about it, so I use automatic and put "gear position" on the dashboard display. I notice when downshifting, the car skips 3rd gear (i.e., from 6, 5, 4, then 2 and 1). Is this normal?

 

Yeah, It sucks when you aren't expecting to replace your vehicle. Glad your happy with the GS!

Engine temp is always almost to the halfway mark. Never seen it go higher. Cleaned the throttle body and MAF with their respective cleaners by CRC. Throttle body was pretty black and probably never done. Sprayed and wiped, then sprayed the MAF as directed. I did the oil change A month ago and this week (about 650 miles later) I was 2.25qts low. I put 6.7 in. My thought was possibly the cleaner degunked some seals/gaskets and made a pre existing leak worse. I'm going to try going back to Dino oil. I had the oil light come on before changing it, but wasn't sure off the last oil change, and with the history of these engines, figured it was just burning it. (No oil on the ground)

I tried disconnecting the battery when it first started. That was a few days ago. I drove normally after though, not slow as suggested.

I'm assuming I can take it to my local Toyota for the techstream check-up? My nearest Lexus dealer isn't local.

Really appreciate the help and advice!

 

A few things come to mind.. I've no experience with the fuel cleaners you used, I assume they are concentrated. There has been cases where owners ran lower octane in these cars, the fuel system was so contaminated when fule a cleaner was used the debris plugged a few injectors, although rare.. I do use seafoam and not more than 1 OZ per gallon. You could try this, however it will take a few tank fulls if its going to make a difference. The shift points are off albiet if you shift manual or automatic and this is really not the issue, as your issue is underlying. I wouldn't rule out the transmission, perhaps a flush would help or remedy, but I think you had mentioned previously that you tried cleaner to improve the idling characteristics. So, you may be looking at something that was done post purchase. Not stating it was something you did that made matters worse.
I just did a health check on my GS as a matter of fact and yes the lexus dealer would have Techstream to run a full diagnostics/health check. Its unfortunate this is not a simple fix that can be done "online", but my recommedation still is a diagnostic at this point, not to waste more time and money. One thing... If it were my vehicle, I would pull all the spark plugs and check their color and/or compare them. This may tell you something about whats going on..

 

Have you resolved the issue?

 

On a show called wheeler dealers, there was a Porsche Boxster with the tiptronic transmission that shifted poorly in automatic mode, but perfectly in manual mode (like yours) They fixed it by changing the fluid and filter by dropping the pan. I'm fairly positive given the age, mileage, and general tendency for the fluid to not be changed on these cars, that a flush could be the answer.

 

No, not yet.

I put a OBD II scanner on it and didn't get any codes. Was going to take it to Toyota for the diagnostic, but have been tossing around the idea of just buying the cable and techstream software and doing it myself.

Based on 02SDGS's suggestion I'm going to try the fluid change, but still have to get to the bottom of it eating oil.

 

Here is a good start:
Autoprofessionals.org... You will find what you need there in terms of Techstream software.
Become a member and donate.
You will need this: Xhorse MINI VCI Toyota Techstream (J2534) OBDII Communication Interface. Be cautious there are many conterfeits out there. Ideally, you would want firmware version 2.xx. This maybe only available form China (where I purchased mine).

 

UPDATE:

So the other morning, it was really cold (first time since owning the car) and after starting, it was struggling to maintain idle speed and almost stalled. I had to give it gas to keep it running. The CEL came on when it bogged down, but went away once it warmed up. Later that night I noticed smoke coming from the grille. I opened the hood and a light smoking was coming from the drivers side of the engine. Didn't really smell like oil, but also not like coolant, so I decided to take it to Toyota for a diagnostic. I typed them up a sheet of various symptoms with 5 or 6 bullet points (loss of oil, erratic shifting, smoking, etc...) and after about 10mins in the waiting area, the service manager came out with 3 stacks of stapled papers with the Lexus oil usage TSB and other info, and basically said its a $5000 problem and there's the door.

I get that he felt he knew the problem, and was trying to save me the $100 fee, but I wanted everything else to be checked. So I explained that I was aware of the carbon issue, but I wanted it to be put on the techstream to check for any issues, and check for coolant and oil leaks.

So I don't know what all they actually did. They found one misfire code in memory from the other day, and he said its not leaking coolant from anywhere. Said they saw a small amount of oil around the back of the engine dripping down and said that's probably what was smoking. They said everything else was good, or more specifically, "If the computer found something bad, it would be on this paper" I'm assuming they didn't do the multipoint inspection that they said they would do, because I didn't get one of those sheets with all the "we recommend" repairs on it.

You could say I left glad that they didn't say, "blown head gasket" or something like that, but I would have liked to know exactly where the leak was coming from, why the idle "breathes" up and down, and if they really went through the techstream in depth. He did knock $50 off the diagnostic fee, but in a patronizing way... He said, "I knocked half off because you have an uphill battle... The car looks nice though" I guess he was referring to the info in the TSBs.

So I'm going to do a transmission flush, top engine clean, and try some BlueDevil stop leak until I have time to figure out where the external leak is coming from.

 

Sorry to hear. Maybe try reaching out to the dealer despite it being out of warranty?

 

Found out what the smoking was...

While driving my daughter home on a dark back road, I lost most off my electronic systems including power steering and lights. Alternator went.

I never thought alternator because the smoke was in the rear (not thinking the fan was blowing it back) Was stranded on the side of the road with a toddler and I had to take a day off work to get the new alternator in. Needless to say, not too happy with Toyota.