Ok so my check engine light, traction control and warning lights all came on with the message check vsc. Im going to autozone tomorrow to get the codes. Here is the back ground info. 2007 gs 350 rwd

Me and some friends drove from wilmington nc to biloxi ms 800 miles for a fishing tournament with my lexus being the second vehicle, the other was towing the boat. We drove down just fine with me bejng the only one filling it up. On the way back in georgia, about 1200 miles into the trip, my friend fills it up and puts about 11 gallons of 87 octane into it. We go to wendys next door and when we leave it barely idles then dies. We finally get it started and give it some gas. After a few minutes it runs but has a rough idle. About 30 minutes later the check engine light comes kn and says check vsc along with the traction control light and another light. I figured it was the low octane gas. Now its at about half of a tank with about 4 gallons of 87 left in it and 4 gallons of 93 in it. It runs smother butstill idles alittle off. I reset the codes today with the battery but they are now back on. What should I do?

 

Buy a code reader and keep it in the glovebox.

 

Autozone or Advanced (can't remember which) has a code reader on sale for 49 bucks right now, just picked one up.

 

First thing to do, is make sure the cap is on the tank fully and properly - give it 4-5 clicks with a bit of downward pressure.
Forget about the lights on the dash, and drive for a bit each time - after 3 start/stops, the lights should extinguish all on their own, and you'll know it was just the fuel cap not making a proper seal, so the vacuum was off giving the engine management cause for concern.
If after 3 or 4 starts of the engine they're still on, then there may be something else at issue - but as soon as I read the filling up part of your post, I immediately concluded it's likely the gas cap nonsense that somewhat plagues us.
I had it once, never seen it again ever since due to making sure there's no way the cap isn't making a seal around the lip of the neck.

Not all flashing warning lights are a fault with an expensive fix looming - I had one which still puzzles me.
Ran out of fuel......I know, I know!
Refilled and lights went off immediately - brilliant!
Few days later car was being washed and treated with a new sealant - airbag light stays on after the system check routine.
Over the next 2 weeks or so, it's on or off (more on than off though) - thought I'd stuffed up pressure washing one of the parking sensors.
No sooner than a localish ex-Toyota mechanic, whom I'll be using for servicing, plugs in the baby Snap-on code reader, and clears the stored code - airbag light has stayed off, as is the norm.

So, don't fret until you've done at least the gas cap 'fix', and see how that goes.

 

I did the gas cap first. Lights are still on. Bought a reader today and it has 3 codes. P0174 bank 2 system too lean, P0171 bank 1 system too lean, P0101 mass or volume air flow a circuit range/ performance. So im guessing its bad gas?

 

It ****ty gas brother

 

Thats what I was thinking. Im gonna use up this tank and fill back up with some 93.

 

The few occasions I ran mine with 87 octane there were no problems whatsoever. Gas mileage suffered to the tune of about 1-2 mpg, but that's about it. Even my service advisor said 87 wouldn't hurt anything. Bottom line - I don't believe it was the fuel.

 

As above, lower octane just means the engine retards the ignition to suit, so the AFR remains the same.
From other threads, there was a gas cap product code change, which supposedly indicates either a different part or supplier, so you might want to consider that, if you're adamant that the current cap has been put on "fully".

If you want to test the fuel quality theory, go and buy a good octane booster (Amsoil, Bardahl, Nitrous Formula, LubeCorp), and put a few bucks worth of fuel in at the same time as adding the recommended dosage.
Over the remaining time to get through that, your engine should perk right up, and you can then go with BG Products CF5 or any of the Bardahl ones which also seem to use PEA, as per the Canadian website, to clean the fuel system and combustion chamber, or just refill with a high octane fuel if all's well again after the octane treatment.

If things are still not great, then I'd be surprised, and it would suggest something isn't right - maybe check your MAF/clean it just to rule that out before heading to the dealer or independent to have it looked over.


Edit:
Just a bit of an afterthought - your knock sensor might be at issue here. Low octane = knocking = ignition retardation.
Equally, it could just be there isn't enough retardation built into the ECU.

 

I filled up with 93 after getting the tank down to about 2 gallons left. I have reset the codes and I will just wait to see what happens. The idle at first is still rough.

 

Thanks for the suggestion to buy a code reader, and where, for how much. Didn't even know you could purchase such a tool - sounds very useful.

 

ok I have driven the car a bunch lately and the engine code keeps coming back. I have just read that there was a tsib for the 06 gs300 for a misfire. My car has misfired multiple times on me before and I am wondering if this is the same problem I am having but my car is an 07 gs350.

 

At the risk of repeating myself - before you presume there's more wrong with the car than a drop of poor fuel, at least run a can of BG44k through the tank as per recommendation.
Combine with Chevron SUL, and drive as gently as you can to make it last as long as possible.
If you see the lights/code return after you've done that, then start thinking about exploring the carbon build-up issue.
Being a 350, has the spring recall been done on it?

Also consider an O2 sensor may be going/gone, and absolutely make sure the cap is on properly - lean on it if you have to, even if only for peace of mind it couldn't be put on any tighter if you tried.

 

The codes I am throwing are for the system being to lean. The gas cap is fine. If i tighten it more then im gonna break the damn thing. Im gonna try the additive thing and hope it works.

 

Lean suggests there's too much air, not enough fuel in the mix.
When that happens, the ECU should retard the ignition, open injectors for longer, so reducing the temperature increase that a lean mixture creates.
As I also said, clean you MAF with the likes of the BG Throttle Body Cleaner.
If we're going to assume it's just a case of poor quality petrol, then aside from the reduced RON, I wonder if the fuel filter has done its job, thereby reduced fuel flow.
I might be inclined to call the petrol station, and ask if they have had any one complain or query their fuel?
You're relying on their honesty, short of returning and taking a sample to have analysed - which presumes it's the same as was put in the tank, and not a refill of fresh petrol.