Hi!

So, last week I bought a 960 3.0 -95. The car was running great when I test drove it, and for the first few days after I got it. During that time the weather was dry, and I only drove it within the city.

Then I went on a longer trip, it started raining and the humidity went up. The car started feeling slow when going up hills. Really slow, almost needing to downshift to second to accelerate up a hill.

After some testing (weather is still wet) it seems that it runs fine on cold starts, but as soon as it gets close to working temperature the engine gets weak.

It always runs smooth, no vibrations or anything. As far as I can tell the head gasket is fine. Theres no smoke coming from anywhere, coolant and oil looks ok to me.

It seems to leak a bit of coolant by the pump, but the temperature gauge always stays straight in the middle, so I figure thats not a problem. I've kept an eye on the coolant level as well, and filled up as needed.

After a lot of googling I'm thinking it might be the lambda sensor. I haven't found anything to say that would be affected by the humidity. But I understand that the lambda sensor is only used once the engine gets warm, and so can cause it to run good when cold but not when warm.

Is there anything I can do to test this further? Any other ideas? How hard is the lambda sensor to replace?

Oh, and the car has a full service book at Volvo.

(I tried to post this without making an account, didn't seem to work but if that post does come up, sorry for double posting :)