Piotr,

Yeah, this winter when they had winter fuel, it ran a little different but I'm talking about variations from Tuesday to Yesterday: same tank of fuel.

jassz, I'd hope that the relatively small temp swing wouldn't change the oil viscosity enough to not lubricate properly. Maybe so, but I'm running Mobil 1 Delvac.

I was wondering if the Diesel viscosity is changing. The OM601 has a fuel heater that should run only until a certain temperature. Maybe mine is stuck in the always heat mode.

ATLD, Sorry, got a manual tranny (thank God with only 70 HP on tap). Also, my car has been converted to R134 so when the A/C kicks in you can surely feel it. And that certainly affects running smoothness, but the effect is present even with the a/c off.

I'm really talking about running smoothness when the outside temp is cooler but not cold. Is it possible that there is a viscosity change on the fuel so the IP doesn't have enough resistance generate enough injector pressure to fully atomize the fuel?

Or maybe the hotter air requires a different injection pump timing value and the OM601 doesn't have a computer to adjust it automatically?

Sholin

__________________
What else, '73 MB 280 SEL (Lt Blue)
Daily driver: '84 190D 2.2 5 spd.