Hi All!
I'm new to this forum and it looks like it has alot of very useful information. Of course I'm posting because I have a problem with my 90 LS400. I bought it used last year with 165,000 miles. It was my first Lexus I have ever driven, and let me say I was very impressed. I have replaced the front calipers, put on new tires and brake pads, and kept the engine oil changed. So far this is all I had to do until these idle problems came about. The problem is that it isn't low idle problems and doesn't effect the way the car runs (it will still peel your skin back when you hit the accelerator). After the car warms up for a couple of minutes the rpms toggles between 1000 and 2000 consistlenly ramping up and back down ever couple of seconds. Even when I'm coasting I feel the car speeding up and slowing down. The mechanic I took the car to said he thought it was the Idle Speed Control Valve ( a $695 part). He cleaned out the throttle body and the air filter which he said was extremely dirty but it didn't help. He recommended trying to clean the ISC valve and see what happens. Anyone have a similiar experience?

By the way great forum!
Shawn

 

perry,

welcome to CL!!! you may want to post this in the LS forums, not the GS forums as for the problem, i have no clue since i never experienced this. good luck with your problem!!!

EDIT: i just noticed that you did post it in the LS forums, why would you re-post the same thing here

 

You may want to have your TPS checked out out (Throttle Positioning Sensor)

Check out www.lexls.com for help on that.