Ok so, looks like sod's law is at play and I tempted fate by posting about my thoughts on switching my car, how good the 2.0 early engine etc. on other threads!
This morning when I was already pushed for time dropping my son off to school, the engine started very lumpy from cold first thing, very similar symptoms to the OP. Switched off a couple of times and it was still quite lumpy. I had no choice but to carry on with the 1 mile drive and it was stumbling and bucking to the point my son asked me why is it so bumpy? Very much like a cylinder misfiring. It wasn't particularly cold this morning compared to previous days.
So I stopped outside school after drop off and plugged in my BT OBD reader and scanned using Torque Pro app. It confirmed Cylinder 4 misfire. Error code : P0304 - Cylinder 4 misfire detected. No CEL, only Start/Stop unavailable and stayed so. All DNA modes were available throughout. I even tried switching modes to see if the misfire would settle down but it didn't. After driving for a couple of miles and may be with engine coming up a little in temperature it seemed to start running OK. Start/stop unavailable warning remained. Power appeared to be back on all DNA modes. I drove the rest 15miles hard in both N and D partly in manual shift mode to see if that would clear the injectors in case that was an issue. I reached work without further issue. Car restarted fine after stopping.
Code P0304 may mean that one or more of the following has happened:
Faulty spark plug or wire Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer
My symptoms sound exactly like what
@Cutterbuck experienced (See Post #14) with the exception that I did NOT get a CEL.
https://www.alfaowner.com/Forum/alfa-giulia/1120322-first-glitch-at-14-000k-miles.html
Some points to note -
1. 3rd service completed recently a week/200 miles ago. New oil and filter. I have asked dealer what oil they used. Car has covered nearly 28k miles.
2. Tank has Shell 95 RON fuel. I tend to alternate between 95 RON and V Power occasionally and predominantly use Shell as it is on the way to work with the odd occasion using Tesco 99RON. The last time I filled Tesco fuel was more than a month ago so I don't think fuel is the problem.
@Twiss002009, I now think the issue could be either a faulty or blocked injector, spark plug (not due to be changed for another year at least) or harness. Cylinder 4 is closer to the cabin - see attached.
I know some early multi air engines on the Giulietta and Mito had the MA unit going faulty or their associated oil filter blocking. I am not sure if the Giulia has a MA unit like those cars and I can't seem to find any info. I do know that the lubrication system also supplies the MultiAir module intake valve actuators with oil it uses to control intake valve opening and also an additional filter screen in the oil supply channel to the cylinder head (seen in picture 2), which ensures that the oil directed to the cylinder head components, in particular the MA module (I am guessing this is the item circled in yellow in Picture 3), is cleaned more thoroughly. The additional MA filter seems to be located by Cylinder 1 assuming I have the orientation correct in my head.
I am hoping
@MacGeek can confirm if the MA unit in the Giulia is different and does not suffer the same issues as the early MA units. If it happens again I will get it booked in for investigation. I might try swapping the cylinder connectors to see if the misfire moves to a different cylinder. I think it is likely a plug, injector or harness issue given the engine seems to be running fine after the initial misfire.