Shalimar

I have owned this car for six months. A great car.... BUT... This is a copy of a memo to my Lexus Dealer at a service 1 month ago. They found no problem. Car now has 39K. Problem is getting worse. I just thought it worth adding to this forum in case anyone else experiences this.

Re: Lexus 2011 LS460 AWD
Subject: Hesitation – momentary loss of power when accelerating after turn.

When accelerating after a sharp turn with light to moderate acceleration, the car will have a momentary loss of power for about 1, 2, or even 3 seconds. This does not happen often, but perhaps once every two weeks and I cannot replicate the problem despite attempting to do so.

In all cases, I am talking about DRY pavement. It always happens after a sharp turn – usually to the right. (Probably because most sharp turns are to the right – actually it only happened once on a left turn that I will describe below.) Acceleration is light to moderate – NOT hard acceleration.

In one case it caused a serious situation. I had just purchased gas and was entering a busy freeway. When accelerating, the engine had total loss of power for a couple seconds as a large semi truck bore down on me with its air horns blaring.

I have a strong clue that may help in debugging this problem. Once, when turning left, the car suffered total loss of power. There was no traffic and I kept my foot lightly on the throttle. The car remained unresponsive. The engine did not stop, but it did not respond and remained this way for at least 5 seconds until I took my foot off the accelerator and then back on to the accelerator. During this period of “suspended throttle” I noticed that on the right side of the dash an orange alert symbol was flashing – I think it was a swerving car? I assume this indicated that the car was losing traction and the computer decided to cut power until traction was regained. But the pavement was dry, and the acceleration was normal. In no case did I ever sense that one of the wheels was slipping.

Unsober1

Well then I think it would have to be a traction control issue. Do you live in an area where there are icy roads. The situation you described was the exact same as when you hit the gas and the car has no traction like when on icy roads, at least where I live. Your throttle is saying send power, but the traction control is over riding that responce. It could we something slipping in the drive train or an electrical issue. That's my guess

Devh

I think your problem could be related to the traction control unit. More specifically it's probably a faulty yah rate sensor. It is not a common problem but it can happen and when it does it will cut power to the engine. In your case the sensor is probably out of bounds because of a calibration issue.

Unsober1

On my old 430 I had the light come on and ran the code. Some people said it was that yaw sensor issue also. It was easy to reset. Just had to short out a few pins on the input under the dash. Do a little searching and try to rest it. Might be a really easy and free fix.

greg3852

Would leaving the battery disconnected reset everything and maybe resolve this? I would try it.

NobleSpine

My 2007 LS 460 used to do it right after oil changes. However since last two times I have changed the oil to 0 (zero something) based on the service rep's recommendation at the dealership and it has not occurred since.

roadfrog

Ditto. This is my second oil change with TOYOTA 0w20. No hesitations since (approx 6 months and 12k miles. The previous oil changes with various other oils, always produced hesitation.

Pretty clear it's not coincidental.

hms09

I can't imagine what an oil change would have to do with hesitation. Can anyone offer a reason this occurs?

roadfrog

The very finicky VVT-I system that our LS' have. Even the labels on the Toyota oil containers refer to the VVT-I system specifically. To add to the argument that the use of improper oil is a culprit, when I switched from Toyota oil to various brands and weights of oil, my problems started. I went through two oil changes with non-Toyota oil and had episodes of bad hesitation. As soon as I changed back to the Toyota 0W20, it stopped. I have now done two oil changes using the Toyota oil have not had the issue re-occur. It's not a coincidence.

305Busa

i have a couple of suggestions but the last one is totally at your own risk. First, try and drive the car in "power" mode and see if it still does it. This usually drops the car into a lower gear which makes it feel more torquie. Next suggestions is try and make a turn while the TCS is completly off. But dont do it in public or with a truck barreling down on you. Maybe an emtpy parking lot or something. If it responds the way it should, then it can perhaps be the yaw rate sensor as stated above. But please, do not press the accelerator all the way down with the TCS off, just a normal acceleration as if youre pulling out into traffic. I did it once and got the car sideways like it was in a drift contest.

Shalimar

(I started this thread )

I have tried some of the suggestions and switched to using power mode at all times which seemed to help slightly. However, the car still has intermittent momentary power losses. Once again, on a left turn into traffic, the engine had a power loss while the anti skid light came on. Note that these occur on dry pavement and I am NOT hot rodding.

Oil was changed and I noticed no differences like some people report. I am using 0-20 synthetic

I know other people have reported this power loss and I wonder if it is unique to the AWD version?

I will pass on some of the suggestions to Lexus Dealer next time car is in for service. Last time they were not very sympathetic. Very disappointed with this car.

SW17LS

This right here tells me the issue is with the traction control system. Try turning TRAC and VSC off and see if if still does that.

I'd be very surprised if oil caused anything like this. I've had Lexus engines with VVT-I for many years and have never specifically used Toyota oil and have never had any sort of issue like this.

Doublebase

I'm having a similar problem, but without the traction control light. It happens when already moving at a low speed and I switch lanes, etc. There is a little hesitation - almost as if the transmission doesn't down shift, or the fuel is being stopped momentarily - it doesn't happen all the time, but it does happen. I usually floor it and it finally responds. I figure it's an 8 speed transmission and there are a lot of factors that go into a gear shift...something is amiss.

As far as I know the VVT system on this vehicle is an electric motor type that is attached to the front on the camshaft, with a speed sensor reading the back of the cam, and adjustments are made through the combination of the two. I don't think oil effects it (edit, the exhaust valve is still controlled hydraulically, while the intake valve is controlled by an electric motor).

I don't consider it a problem, but I guess it could be a dangerous situation if I pull out in front of a Mack truck, with little room to spare. I've run TGMO and it hasn't helped the situation for me. Personally I think it's a software issue.

roadfrog

Yeah, 100% - totally different issue.

As for me, as you can see from my posts above, this is no fluke. TGMO in the correct viscosity (0W20) and AFTER an oil system cleaning with Toyota VVT-I oil system cleaner (about 25 bucks), has completely solved the hesitation. About 16k miles now with no hesitation. Before, EVERY oil change with several quality brands of oil caused hesitation. Changing to proper oil, solved my problem and a few others as well. Member DevH clearly explained somewhere how the VVT-I system IS dependent on oil. Micro mesh screens and other components are all oil bathed. As I also mentioned earlier, the TGMO and cleaner mention the VVT-I system.

Also, if this issue were a software problem, it would not occur ONLY after an oil change and then disappear after a few hundred miles or weeks until the next oil change. The car's system doesn't know that the oil has been changed. Some owner's even left the oil monitor un-reset, thinking that maybe the monitor was messing something up. Didn't help.

To be clear on what my particular hesitation behavior was, it happened in diffferent scenarios.

1. Accelerating across traffic from a stop light
2. coasting to a near stop (5-20 mph) and then trying to accelerate back up to speed.
3. depressing the accelerator to go up a hill

In these circumstances, it feels like the trans won't down shift, but it does and the RPM's climb in conjunction, but the car doesn't respond. It's impossible to miss.

SW17LS

That just doesn't make any sense...I don't have a ton of experience with the 460 yet but I have had 5 other Lexus vehicles with VVTi, including a 400 and a 430 and used multiple different types of oil with no issues.