My wife has a '98 S70 (non-turbo). Recently, it has developed an occasional "stutter" in the engine while sitting idle at a stop light (in gear, auto tranny). The tach drops a hundred RPM's instantly and goes back down to normal.
Has a new air filter, new plugs, did an oil change, checked everything I know to. There isn't any report from the CPU about "check engine" so there aren't any codes being picked up. The new plugs were not my first choice (just standard autolite's, properly gapped to 0.28)...could this be a fouled plug? (they have about 3k mi. on them). I don't know whether or not this started after removing the factory plugs (at 37k mi.) and replacing them, but, thats when I first heard of it so it may be so.


The other oddity...is the two center console vents do not blow hot air. All other vents seem to work fine...except the two center console vents. They still blow air, but, its cold and all the other vents are hot. I've monkeyed with all the climate control settings I can find and nothing seems to change this. Any ideas on this one? :-) I'm beginning to think something chewed through a hose or something! <img border="0" src= "http://www.motorcars-ltd.com/ubb/smile.gif>


thanks in advance for any ideas!</P>

 

I don't know about the vent issue but the idle problem may be a loose/cracked/or other wise bad vacuum line.

 

that stutter could likely be a cracked intake manifold, that happened on my 262

 

Spark plugs can make a big difference sometimes. I know that our Volks Jettas came with Bosch plugs and you didn't dare chage to something else. I did and had hestitation on acceleration, lower mileage and a rough (well rougher than normal) idle. It probably wouldn't hurt to pull the plugs and compare the look of them cylinder to cylinder. Sometimes plugs from different manufacturers will fill the hole but not run hot enough to stay clean or get too hot and burn up a little. I have only had a Volvo a little while so admittedly I don't know what plugs they come with from factory but they are likely your best replacement. Thats my thoughts.

 

The vent issue is intentional. If you have the manual, read up on it. They say the center vents blows "fresh" air and to get the cabin heated up you need toclose the center vents. It doesn't make much sense to me, but that's their story.