'84 240 vibration at idle PLEASE HELP!!!

The fuel window on those cars is very narrow, which means that the throttle body must be clean and set up properly. Go to your local Volvo dealer, walk into the shop and find a tech who does side work. Doing this pays 1 hour, but can be done in 15 minutes and makes an amazing difference in how the car runs.

I have heard that the motor mounts on 240 's are notorious for breaking. Mine had two broken ones but the idle was still normal. Rojo

I'd guess a bad motor and/or tranny mount. Mine went at about 125K. Not an expensive or difficult fix.

-jeff

It could be the motor or tranny mounts, but you'd think they would have caught that. On my '92, I had this thing happend where the exhaust was hitting but only when the engine was loaded up, and it created a vibration that was very difficult to diagnose...

-jeff

Another thought I have. I had a rough idle and it turned out to be corroded spark plug wires (just two). I would recomend checking the spark wires especially if they are old. Mine weren't but in washing the engine, months ago, water must have gotten inside the caps and corroded them. The sign was a white powder packing inside the caps. I cleaned them, no difference, replaced them and the car idles and runs fine. Best of luck, Rojo

Turns out it was the throttle plate and throttle switch, after a lot of complaining, the dealer did this for free! They also replaced the coolant temp sensor, there is still a bit of a vibration, so I need to check out the motor mounts, thanks for all the help.