So I have this situation where my 740GLE runs better at night than during the day. Wiers, but considering I am in the "deep south" it might make some sense.
Overall, accelleration is much better when the ambient temp is below 88deg F or so. What gives? If the change in performance was based on engine temp, I would look to the FI temp sensor but that makes no difference.

Compression is within 7 PSI between all cyl, vac is steady suggesting OK valve train, plugs are picture perfect. Subsequently, the car shakes a good bit but that could be the tranny mount or the "free-form" exhaust mounting.

All I can say is that in the middle of the day, the diesel Chevettes are winning! ;(

Trey

my car definitely runs better in cold weather than warm, but i know that is because my fan clutch has engaged during hot weather. the roar of the engine is noticeably louder, and definitely has a harder time picking up from a standstill.

i don't know if you may be referring to that though because it sounds like you're talking about a very HUGE difference.
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Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

Check your air flapper in the air box: it may be stuck in the "hot" position. Any intake air leaks (holes in the tubes, etc.)?