snoball

OK guys!!! We have figured it out......I hope.


After consulting with NorthSide Lexus here in Houston, one particular mechanic has seen this issue many times with the 460 motors. LS460's and GS460's are common with this problem.


It seems that the wiring harness that plugs into the transmission collects fluids/dirt over time. This causes the transmission to go crazy and its why it is intermittent. So far the tech has fixed it, about two days ago, and still no lag or shifting issues. I told him to drive it till next week as I am going on vacation this weekend. Just to make sure it doesn't resurface.

ptan1968us

iTrader: (1)

^^^ How much did they charge you if you don't mind me asking?

snoball

I actually haven't gotten that bill yet. It will be next week before I know probably

TRD_Power

That means they're still adding up all those zeros Jk Hope they got this figured out once and for all! Keep us posted.

snoball

LOL
Your probably right! Thanks and will do.

designo

iTrader: (6)

Interesting, I always thought this was a symptom of the 8 speed tranny.
Do you drive in "power" mode? ( I believe in the US it's called something else )

Tuna713

I'm not sure how bad your lag is, but in mine it feels like the engine winds up and then like a turbo it kicks in the boost. I'm inclined to believe it may have something to do with the 4.6 bottle necking through the 2" exhaust. But I'd like to know what you asked them to do so I can test your theory first?

designo

iTrader: (6)

Naturally, the 4.6 motor hooked up to the 8 speed is torquey after 4000 rpm

snoball

I drove the car in every mode. I even tried manually shifting, which seemed to help at certain times. But no matter what the shifting got so bad that I was unable to safely drive the car.

snoball

What I asked them to do??? I dropped off my car and asked them to fix my ****!!
Bottle Necking through exhaust? Highly doubt it will cause the issue you just described.

snoball

I agree with this statement.

snoball

Picked up my car last night. It is running soooo much better now. Had a chat with tech and Service Writer.


Tech said that all he did was clean the connections hoping this would last and solve the problem. But in some cases the wiring harness needs to be replaced. This is because the fluid can work its way into the harness and travel upstream inside the wires. He also said that he has actually seen fluid travel all the way to the front of the car inside the wiring harness. Basically like a cancer.


Now, what the Service Writer said..... NO CHARGE!!! I thought he was kidding and said "HA, I wish. So how much?" he said it again, NO Charge.
He also mentioned that they have put in a claim to Lexus about this issue as they have seen it on the LS more than anything. Not very common for the GS though. If I do need a harness he will try to get Lexus to pay for it but no promises. If they don't it will be about $1500. AND BOOM GOES THE DYNOMITE!!!!


He also tried to tell me the LS and GS have different transmissions. I told him they are not different and needs to do more homework. I think that is his way of adding a loop hole for Lexus not to pay for it. If this is a known issue then Lexus needs to step up. It's not my design flaw.


That's it for now. and hope I don't need a wiring harness.

703

I have also noted the tranny holds a gear for longer in the cold during hard acceleration from low speeds. When it finally shifts, its more "jerky".

Anyone observed this?

Doublebase

There's a thread a mile long on the LS460 side of the house for this same issue, I'll give a quick breakdown of some of the ideas people have thrown around.

Fuel--The 4.6 engine needs its octane level correct or it will retard the timing through the knock sensors.

Transmission internal leak at the valve body--A few have had a rubber seal easily replaced at a wiring harness.

Transmission reflash-- A quick reflash has helped some.

Oil change-- many have complained about the hesitation immediately following an oil change for the first 500 miles or so, then it goes away. The variable valve timing is thought to be the culprit. Perhaps oil aeration? And some have blamed quality of oil/oil weight/dirty oil that is freed up after a change.

Valve guide wear-- This one scares me. A few people have had their heads replaced due to valve guide wear. The valve rattles in its guide causing the knock sensors to kick in. Immediate hesitation. This is the unicorn in the room...few have had this repair done...and Lexus uses it as a last resort (it's an $8,000 dollar repair).

I've experienced a hesitation occasionally...doesn't bother me...I attribute it to fuel quality. Whenever I use midgrade gas I know I can get this hesitation. Then I run super for a few weeks and it never happens. I use midgrade once in a while because I drive a lot and I figure...hey why not save a few bucks? Maybe I shouldn't.

snoball

ok the issue is back again.....just not as bad. The Lexus mechanic said this might happen and the wire harness inside the tranny will need to be replaced. He admitted this happens a lot with LS. I'm going to try and get Lexus to pay for it as they know this is an issue. Only problem is that there is not any TSB's or recalls on this issue yet. Lexus has managed to keep this very Hush Hush.