I have just bought a 04 V40 with 45,000 miles. It runs great, and I am very happy with it over all. We purchased the car in Phoenix AZ and have driven it to our home in Durango CO. The first morning when we got in it and started it up, it started up and ran nice and smooth. The second morning that we had it we started it up and it idled rough and seemed sluggish, the tach held firm at 1200 rpm though. We have not noticed any extend cranking like many have described. Since then every morning has been similar with the rough start. These mornings have been in the mid 30's, the first morning (good start) it might have been a little warmer. Yesterday at some point while my wife was driving it it through a code P0303 Cylinder 3 mis-fire. I don't know if it is related. Yesterday I replaced a piece of vacuum hose that runs into the Fuel Pressure Regulator. It ran a little better this morning, but was still rough and sluggish, I also had the hood open and heard some light valve clatter. Some other back round on the car, It has had to be serviced prior to passing smog in both CA and AZ according to the CarFax, It look like the PO just had the spark controller changed and the spark plugs changed, but I did not get any receipts for that work (CarFax record). The oil looks fresh and clean, and there are some new vacuum hoses and H2o Hoses. I have not done any other testing or inspection.

I have an odd theory that I want to bounce off of you guys:

1. The car was from Phoenix AZ a place that is still in the 90's during the heat of the day, could the PO have used a heaver oil that is appropriate for the local conditions. But when I start it and it's in the 30's the engine really has to work hard to push the thick viscous oil through for a couple of minutes. Could that extra friction cause rough idle and for a little bit?

What grade of oil are you using in areas that have sub freezing temps? I saw one guy mention he was using 0-w40 synthetic, any thoughts on that? I've always been a little scared of the 0-w40 myself.

Any additional thoughts and experiences would be appreciated.

 

I am still getting rough startup in the morning. I have gapped the spark plugs. They are Volvo plugs, but were gapped at about half of the spec in the owners manual they are now gapped to .8mm. I also swapped the coil packs, but have not got the codes read to see if it through a new code this morning on a different cylinder.

This after noon I went about cleaning the Idle air control valve. I am concerned about what I found, but I don't know if it should be this way or not. I definitely removed some built up varnish and carbon from it. While I was inspecting it I noticed that the orange plunger was not seating all the way in the valve body. Those of you who have seen a known good unit could you please let me know if this is a problem or how it should be in an unenergized state? I have tried to include a couple of pictures for reference.

 

Yesterday it seemed to startup a little better, but was still rough at idle and when I revved it up a little, 1500-1700 rpm. So yeterday I cleaned the throttle body and the MAF sensor at the air box. This morning when I started it up it started nice and was not very rough, I might even say smooth at idle. When I gave it a little gas it felt like it was missing on one cylinder at about 1500 rpm, but smoothed out around 2,000 rpm. This morning it was a little warmer outside, than it has been.

Does anyone have any ideas what would cause such a narrow and specific problem?