The chap who altered my map file 'Thomas' altered the following for me.
Longer glow time at low temp
reduced swirl activation at low temp
extra 200 RPM at low temp
and changed the timing from 1 deg after to 1.5deg before DTC
My problem is 100% cured by the MAP changes detailed in the link above and also fitting the correct Glow Plugs. My 07 plate 2.4 is supposed to have the more expensive GN069 plugs.
My car also has DPF removed, EGR deleted and a performance map.
There are two types of glow plug for the 159/brera 2.4. Shorter bosch/NGK 13amp plugs and longer (more expensive) Beru GN069 20amp plugs.
My car had a mix of both. (2 x short and 3 x longer). I replaced them all with shorter ones at first, But later swapped them all for 20amp Beru GN069's. The longer 20amp Beru plugs will get the engine pre heat done faster. The info that the longer plugs are only for 4x4 models is wrong.
But you need to be sure they fit your car.
Anyway my issue is 100% gone with the map alteration and longer glow plugs. And I run my car on Bio-diesel which is more likely to be harder to start from cold.
But what fixed my issue may not fix yours...
If I wait till the display says 'push clutch and start' - it starts within 1 or 2 seconds of pushing the button. No shudders, No need to push accelerator, No Smoke. And yes thats from cold after sitting all night.
Read this following thread before you do anything with the glow plugs! I only know that my car takes the longer more power plug. I have no idea if yours will.