toyolaxus

Hi I have a 2004 LS430 with over 309,000 miles with original trany. It runs OK except for this one weird problem. When it gets to about 35-40 mph, at relatively low RPM, the car's engine will shake/vibrate quite noticeably. Give it a little gas and the speed move out of the range, and the car goes back to normal. It recently developed a P0357 code which means I need to replace the ignition coil at cylinder 7 or G. I am going to replace all spark plugs and coil pack just to make sure. But do you think this could be something else?

Another hint, the car does leak a little bit of something quite dark (I don't know if that's oil or some other kind of fluid) but in a very small quantity. Also, the car's engine bay smells like a bit of burning oil. I had mechanics checked it out and they didn't think it's the head gasket.

What's your recommendation?

Thanks!

TarXan

The shaking is likely due to the engine misfiring. You can try swapping coil pack #7 with #5 and see if if the problem follows the coil pack or not. You shouldn't have to replace all plugs and coil packs.

BigBoomer

Also check the engine/trans mounts. The engine really shouldn't move much.