Hey. I've had my ISF for about 3 to 4 months. I absolutely love the car and i haven't seen too many of them in this area (central NJ). I wonder why lexus hasn't done a better job of informing the public. Most people don't even know that lexus makes a V8 sports car.

My question is as follows - when the car is on idle, there is this strange vibration that i feel coming from under the seat. It happens for a few seconds and then stops and starts again when the car is on idle. It happens when the car is not warmed up, but also when the car is properly warmed up. I'm not sure if its a cause for concern. Is it because of the timing belt? Engine? Just want to make sure its normal and have the car looked at if its not. Thanks you.

 

not normal i would go to lexus. my car is smooth once its warm.

 

Could Be the idle affected by the A/C compressor turning on and off. Have it looked at.

 

its a very strange occurrance and it happens all the time. i can only describe it is its smooth, and then at certain points it will start rumbling then go smooth and then back to rumbling for a bit.
Does anyone have a good way to explain this to the service rep. I've experienced that whenever you tell them about vibrations or noises, they give you the "its normal," or is because of the "powerful engine" speech and make you feel like an idiot.

i hope its nothing serious.
thanks.

 

Mine will vibrate sometimes, but its a very subtle vibration and seems normal... If its enough there you can feel the car jump a little, then I would take it to the dealership...

Either way its under warranty just take it by there and they will cover it

 

Perhaps next time you observe this vibration...glance over at your tach and see where your engine rpm is running.

 

the RPMs don't spike during the vibration. I initially thought it was a timing belt issue, but not sure anymore. Does anyone live in Central NJ have a good service dept. to recommend?

 

This is my 2pennies, lol when you first start up your car in the morning, the cars cold, obviously, during the heat up process, the car trembles a bit mainly cause the computer is still deciding what rpm to bring the car to at idle, it might be in one of those in-between temp/rpm phase, making it idle a bit rough, I noticed that on all AUTOMATIC transmission car especially cause theres a minor load on the engine too with the trans, dont realize it as much in manual cars cause its in neutral all the time if its not in gear. Next time when you feel the vibration, put your car in neutral and rev it a few time, by doing that, it will bring the temperature up and the car will idle at where its supposed to be at and should smooth out, I can almost guarantee that you dont have this issue when the car is fully, fully warmed up, and that doesnt mean 5 mins after you started the car in the morning. I mean, like hot as the fan is almost ready to turn on kinda warmed up. try it out

 

Oh, one more thing, if the car is still doing it when its fully heated up, try switching gas, I noticed my car trembling a bit more than normal when I used the USA gas down the block from my house, I immediately spent $5 for an octane booster and voila, car was super smooth and I havent went back to USA gas since. Im thinking their "93" octane gas is not 93.....

 

There's no timing belt in this engine. It has chains. They're not going to make a vibration. Check the A/C charge, it sounds like it might be low and the vibration is the compressor cycling on and off.

 

i have noticed same vibration few times sitting at stop lights and this is when car is fully warmed up. Very minor engine vibration...Everytime i have gotten this vibration RPM Tach has always read about 500 which i thought was pretty low....Normal should be around 700-800

 

hey guys... in case anyone was curious, i got my car back from the dealership yesterday. They attribute the vibration to the car changing the fuel intake when in idle for more efficiency and when i accelerate, it opens up the intake. It sounded like a guess more than anything and they only kept it for a half day, so i can't say they tried too hard. I inquired about the A/C charge, but he said because i told him the air conditioner has been working fine, he didn't believe that was an issue. He also stated there were no TSBs for it.
So, i have two options
1) Let this bother me and obsess over it till i lose all enjoyment i get from driving the car, or
2) believe the service tech and move on.

Thanks for all your help

 

Sounds like the K and N Filter should solve your problem!!!! LOL

 

I've noticed this in my is250 2007 to, it's very subtle but apparent...

anyone find the root cause to this?

 

Funny you should mention this...

If I idle with all lights off I am in the 500 range...in Drive mode with foot on brake

If I turn on the head lights or even just the parking lights I am in the 700-800 rpm range... in drive mode with foot on brake.

When I click the light stalk On or Off I can see the rpm drop and/or rise by 300 rpm

Try it out..

Joe Z