bouncing tach at idle after freeway speeds

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Jun 9, 2003 | 08:18 PM

ibike

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Driver School Candidate

Joined: Nov 2001

Posts: 4

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bouncing tach at idle after freeway speeds

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?

Jun 10, 2003 | 02:57 PM

James2210

Driver School Candidate

Joined: Mar 2003

Posts: 29

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From: International

Sounds like it could be misfiring. I'm not too familiar with the ES300 (I have a GS300) but I guess the engines are pretty similar. I had a similar problem once on the first GS300 I bought. That was supposedly caused by damp although the dealer never did fix it 100% so I rejected the car and got a different one. Also check the coil packs (the things that the spark plugs are connected to) as they are quite notorious for breaking down if they get too hot. Apparently, it's something to do with the insulation breaking down and they fail to produce a spark. My wife had a problem with her Mazda and it was recalled so that improved coil packs (sometimes called igniters) could be fitted. I also know that VW/Audi are currently recalling a lot of european cars because of coil pack failure. If it is a misfire (could explain nasty smell), I would not recommend driving as you could be blowing unburned fuel through the catalytic converter which would then ignite inside causing it to get very very hot and might melt the core.

Good luck getting it sorted.