Rough Engine Cut In And Out

[Robl45]

I think there was a topic on here or another board talking about the engine feeling rough when it cuts in and out. Did anyone get this fixed? Mine shut off at the stop light yesterday and shook the car. And when it comes on, you can feel it. I didn't notice it when we first got the car a month ago, but it seems to have gotten worse.

[RX400h]

Ours did get a bit more noticable, but not so much that it bothers me. Still, it wouldn't hurt to ask the service advisor if the factory has anything to say about it.

[katzjamr]

mine got more noticable when i switched from regular to premium gas, its still something that i consider in the range of normal.

[Robl45]

mine when I stopped at a stoplight cut out, but it was kinda like it ran for a 1/2 second, like diesal run on or whatever its called. I just thought I read about people taking the car to the dealer to have this fixed, maybe I"m nuts.

[longo]

im also having the same problem an im at around 10k also is anyone having ruff startups, it seems like every morning when i start the car it starts up really rough

[Robl45]

yes,same thing, i'm noticing rough startup as well. I don't think it should be like this.

[LexRexBlue]

I had the same experience. Despite all the literature I'm not getting any better mileage with premium and there's about 25 cents a gallon difference so I've gone back to regular. Pick up was a little faster with premium but I have plenty without it. You can hardly tell now when the engine is on/off.

[Gryphon]

Man I gotta wonder why you guys buy an expensive vehicle designed to run on premium fuel, then think you know more than the manufacturer and decide that regular's just fine. Do you think that Lexus gets a kickback from each tank of premium pumped?

[skyfish400h]

im also having the same problem an im at around 10k also is anyone having ruff startups, it seems like every morning when i start the car it starts up really rough

Mine started at the 20K service. When I took it in... smooth. When I got it back... rough (rougher when cold).

Dealer says they can't find anything wrong with it... hmpf.

It's not bad. It's not missing or hesitating or anything like that. Just rougher that it was when it was newer. I've noticed a similar roughness in the loner 330s that I've driven. I remember thinking at the time, "boy I'm glad my car is smooth... guess I jinked myself ;)

[RX400h]

Man I gotta wonder why you guys buy an expensive vehicle designed to run on premium fuel, then think you know more than the manufacturer and decide that regular's just fine. Do you think that Lexus gets a kickback from each tank of premium pumped?

From what I understand, our engines are NOT high-compression and do NOT require premium fuel. The owner's manual states that regular gas is just fine, if I recall correctly.

Maybe someone can post the manual's statement.....

[Gryphon]

I can only speak for my 2007...the manual specifies "premium unleaded gasoline with an octane rating of 91 (Research Octane Number 96) or higher required for optimum engine performance."

Tom

[larrytrk]

I had the same experience. Despite all the literature I'm not getting any better mileage with premium and there's about 25 cents a gallon difference so I've gone back to regular. Pick up was a little faster with premium but I have plenty without it. You can hardly tell now when the engine is on/off.

MY understanding is if you switch fuel grades, several tankfuls may be necessary for the computer to optimize to the change, before mileage change occurs!