Hi all.

I have a situation. I have just purchased a 93 LS 400 at 124k. My LS 400 car slightly shakes intermittently which is noticeable during engine idle. I took it to a local Lexus Dealer, who suggested that the engine could be misfiring abit and said the spark plugs need to be changed. However since it had a full Lexus service history I checked with the last service dealer for the work done and it turned out that the spark plugs were just changed along with the timing belt at 120k. My local dealer then said that the exhaust blow maybe a problem and I had these checked but everything looked ok to them. Finally they have said that they would need to do a detailed investigative check which can take a long time and a lot of pounds.

Have any of you faced this? This could save me a lot of money. I know this maybe not very common, but I'm just hoping one you folks can help me.

Thanks a ton!

doe,s it happen when your cooling fan cuts in as it could be that doing it

timing chain?
my old jag had the same, never got it fixed though, that's why i sold it!
maybe it's not getting enough air?

Isaac, your problem may be more common then you think. I also have a 93 with 100K that just started doing the same thing. I am going to be looking at it this coming weekend and will let you know what I find. I am going to start by looking at the condition of the throttle body plate. My idle is a little unstable with a slight stumbling and a hesitation when taking off from a stop, it seems to run fine at highway speeds.

Curt

Check for a vacuum leak. That is a typical symptom of such. when one of the hoses cracks. An easy way to find it (if it is) is to spray some carb cleaner around the vacuum hoses. If there is a leak, it gets sucked in and you'll hear then engine speed increase.