ibike

I have a 98 ES300 with 60k miles that has a weird problem. Normally it idles at 600rpms and idles smooth. If I drive local roads (55mph or less) I have no problems. However, if I get on the freeway and go 65+mph, the idle gets screwed up and when I drive at low speeds are come to a stop after that, the engine surges and at a stop the tach bounces from 200rpms to 1000rpms and the whole car shakes. If I turn off the car and let it sit for 10 - 15 minutes and start it back up, it's fine until I go on the freeway again. When the idle is bouncing, there is a very strong sulfer smell that is not there when the car is idling normally. Once after this happened, I had to sit at a railroad crossing with the bouncing idle and after several minutes, the check engine light came on. I didn't get the code read at the time and after a day the light went off. So I'm guessing it's something in the emission control system like the oxygen sensor or something like that. Any ideas?

flipside909

You have rough idle. When's the last time your car was tuned up?

beab951

My guess is that your idle controler is having problems. Sometime a little WD40 will break up the carbon formed inside and it will work like new. It could also be the computer trying to keep the car running because of a poor burn situation. The O2 sensor shouldn't cause the idle to surge like that, it is a fine adjustment to control the AFR (14.7/1) for the Cat. The strong smell indicates that the car is running rich. As stated above, do a tune-up before you plow into replacing parts.

ibike

I bought the car used at 36k miles. I haven't had it tuned yet. I'll do that. Thanks for the feedback.