98 Ls 400

[xbukeye]

I just purchased a 98 LS 400 with 42,000 miles from a private party whose records show service performed at all recommended mileage dates. It is a great car however it has one thing that is annoying. It is almost impossible to accelerate smoothly from a stop. When I push slightly on the accelerator pedal nothing happens so I continue to push and then it takes off. I also get a feeling that it surges when I am cruising along at 65+ MPH with my foot just resting on the pedal. The Lexus people told me that this is because of the electronic fuel system and is a characteristic of the 98 model. Has anyone else heard of this? Can it be adjusted? I can learn to live with it but it seems odd that they would permit this to exist. I would appreciate any comments/suggestions.

[JMRussell]

I have a 98 LS too and have not experienced the problem you are talking about. Is yours an early or late model 98 as it changed during the year? I would have thought such a problem was unacceptable the take off in mine is beautifully smooth. There is a big difference between a gentle take off and a quick take off with little in between and certainly if you start of gently and then wish to accelerate there is a bit of a lag but I've always put that down to the gearbox as it shifts down.

As for surging - nothing. The LS is probably the best car I've ever had for cruising.

I would think there's something amiss with the engine management system. Even if you bought it privately if it's got a full Lexus service history you may be able to buy the lexus extended warranty - as new car warranty.

[xbukeye]

This car was originally purchased in March 98. Do you know that there was a change in the fuel delivery system during the year??

[JMRussell]

Mine's an August 98 and officially the mark IV came out in January 98 but I've seen very few registered before mid 98. Do you know if your is the MkIII or MkIV.

I did not think the mechanicals had been changed much (but see below) as most changes were trim/cosmetics etc but Lexus might be able to tell you. I like you can not believe a fairly basic problem like that would exist an what is an expensive car. Friends of mine who've had older versions than mine have never mentioned your problem.

Looking at the basic tech specs from Lexus between the MkIII & MkIV the engine looks very similar - compression ratio is up 10.5 from 10.4 and BHP/Torque increased though the later model is much quicker despite being heavier. This is probably due to the improve suspension and the 5 speed instead of 4 speed autobox. They did update the electronic throttle control system (no idea what this does) and brought in variable valve timing.

Probably doesn't help much.

[xbukeye]

I have the original window sticker but it doesn't indicate MK3 or 4. It is 4 liter, 290 HP, 4 cam, 32 valve and is the 5 speed. Would this be the MK4? How did you know about the updated throttle system? This might be a key to my problem. Thanks for taking the time to help.

[JMRussell]

Sounds like yours is the MkIV same as mine. The updated throttle system was included in the spec archive on the Lexus GB site.

[helio]

Sounds like yours is the MkIV same as mine. The updated throttle system was included in the spec archive on the Lexus GB site.

Oops , new at this... sent my message to JMRussell...

Again... I also have ls400 98 MK1V (jap import) with same problem. Jumps from stop , have to be quite gentle with the accelerator else she surges... just to let you know I'm in the same boat.

[Hawkman]

My 1998 has always been that way. Maybe not so bad from a standing start, but it's really annoying if you're in a slow rolling stop, and then get back on the gas. Big lag sometimes, then the gas kicks in and whips your head if you give too much gas. Was told it was due to the electronic throttle and was common on that year...since it was the first year for the ETC.

Is there a fix? Did Lexus admit the tranny sucks and offer a solution? Thanks!

[Xkalaba]

I just purchased a 98 LS 400 with 42,000 miles from a private party whose records show service performed at all recommended mileage dates. It is a great car however it has one thing that is annoying. It is almost impossible to accelerate smoothly from a stop. When I push slightly on the accelerator pedal nothing happens so I continue to push and then it takes off. I also get a feeling that it surges when I am cruising along at 65+ MPH with my foot just resting on the pedal. The Lexus people told me that this is because of the electronic fuel system and is a characteristic of the 98 model. Has anyone else heard of this? Can it be adjusted? I can learn to live with it but it seems odd that they would permit this to exist. I would appreciate any comments/suggestions.

Hey,

I am experiencing the same "surges when I am cruisng" in my 98 LS 400. I am able to push the gas pedal and drive right thru it without any problems. These surges are very annoying and I was wondering if you found out anything about it??

Thanks buddy..