Had an odd thing occur today when coasting on the freeway. I was coasting about 60 mph, foot off the accelerator pedal, and the car seemed to not be able to decide what gear it wanted to change into and started jerking back and forth about 6-7 times. When it finally decided what gear to shift to, it suddenly surged from 2K rpm to 3.5K rpm surging the car forward on its own. Anyone else have a similar thing happen?

Just last week, I had the car at the dealership because, occasionally, during a complete stop it has erratic idle where the rpm drops to 500 or under and the car starts shaking. I referenced the TSB posted on this forum (thanks to the member who posted it), but as always, the dealer couldn't duplicate the conditions/couldn't locate anything via diagnostics and did nothing but charge a $105 diagnostic fee.

 

Never happened to mine. Sometimes feels like it cant' decide what gear it wants to be in at low speed stop and go traffic, remedied by using spot mode and/or putting into sportshift and keeping it in first gear.

I think the transmissions are exactly the same between 06 and 07+ 300/350 so everybody experiences this... BUT, it has always been rock solid on the freeway or moving at any kind of constant speed. But over the last few months they have also changed out my ECU and O2 sensors with redesigned parts as well trying to help me with my rough idle. Could be that everything they did had a cumulative effect.

I've also noticed the car doesn't hesitate like it used to randomly when stepping on the gas.

 

How do you put it first gear for sportshift so when you go back to normal driving and switch back,it shows 1 instead of 5?

 

Nothing you can do about it. When switching from D to S, it always starts off in the 1-5 gear range, and when switching from S to D well, it goes back to guessing what to do between 1-6.

 

I have had mine occasionally late shift, or downshift on me when I let off the gas cruising lately i ve kept the power mode and the car seems to act alot better all the way around and hasn t done this to me at all!

 

another one bites the dust.......

Carbon Buildup causing the hesitation, idle issue.

search this forum for rough idle, carbon buildup issues.

 

First of all, thanks to everyone for their feedback. It sounds like I have the dreaded carbon buildup issue... has anyone had luck having the "rough idle" TSB performed by the dealer without a diagnostic code triggering? My dealership appears to be taking a stance where they will not perform this unless that is the case OR the rough idle occurs when the technician takes it for a test drive.

When speaking to the service rep at the Lexus dealership, he mentioned to me the 06 GS300 engine issues are all inter-related, technicians are familiar with the issues, and "common." I find it almost irresponsible of Lexus to not take a proactive stance to deal with the known problems and wait till it's in SOS status or a crucial safety concern.

Spine: Thanks for the tip. I've searched the forums and read through the other posts on the rough idle. I initially thought this was normal with the vehicle over time, but I noticed the engine performs the "shuttering" right before it comes to a stop as well.

 

My dealer would not do anything without a diagnostic trouble code, and even after they got one I had to wait for them to open a technical assistance case which took a number of weeks. How much of your warranty do you have left?

 

1. There is only a TSIB (not a Recall) out with regards to the carbonization issue, the dealer is required to be able to replicate the problem, OR be able to document a MIL status via Lexus' Techstream BEFORE any type of repair is authorized

2. This is a developing long-term issue for the Lexus DI engines- keep in mind carbonbuildup takes time before it actually produces tangible performance symptoms, there is a big chance that many of these vehicles will run out of their powertrain warranty BEFORE carbonization is even detected.
.....time will tell how proactive (aside from the issued TSIB) Lexus gets....This is a true test of Lexus' commitment to product quality, and customer service.

 

Does this issue affect the transmission or can cause damage to it?