OK, I've had this 1996 855 Platinum since June. 216K miles. Runs powerfully and smooth as can be. Turbo spools up nicely. A nicely maintained car as the person I bought it from was another Volvo guy. About a month ago I noticed it started blowing some blue smoke out of the exhaust at idle. Doesn't seem to blow any smoke when the car is moving no matter how hard I accelerate.... or if its smoking at all it is not noticeable in motion. The previous owner replaced the whole PCV system last year. So, before getting into the PCV system I decided to take apart the PTC valve and clean everything out. It was quite dirty and plugged up.

Here's where it gets kind of weird....

The blue smoke seems to still be there... maybe a little bit less. But I noticed that the trip computer was acting strangely afterwards. Not sure if its coincidence or not. The MPG at idle goes down 1/10 about every 8 seconds. I thought it was because I forgot to connect a vaccuum hose or my seals weren't tight- but I double checked everything (twice) and it all looks good. Actual MPG while driving still reads normally- I still get about 19-22 city depending on the amount of stop and go. Yet the computer still drops about 1/10 every 8 seconds at idle. Also, the computer will start reading outside temperature even though the dial is still on MPG. If I turn the dial to the temp setting and switch back it will go back to MPG... but eventually it starts to read temp again in that position. Coincidence?? I know I'm asking a few different questions here.... any help is very welcome. There are no oil leaks, no smoke coming out of the dipstick and engine performance is excellent. There didn't seem to be any play at all in the turbo either.