[johnnymato]

Hello dear tuners, fixers and bimmer enthusiasts, 
this thread might help anyone having problems starting baby bmw in winter, consequently having clogged DPF and consequently having loss of power and swirl flaps error. 

My 116d LCI F20 was starting very rough in winter and the exhaust is already black from inside. Technician's look under the bonnet suggested EGR valve an cooler replacement. 
Did that in autumn, no problems immediately afterwards. 
Professionally tuned the engine to cca. 120KW (tuner spent time on it, usually they can do 107kw, but we had power delivery problem (written at the end of this post) so tuner tried to compensate it, without success, but optimized the tune for more power)

Next winter came, problems with starts came back. 
Replaced glow plugs (bear in mind there are 2 standard and one with sensor (costs cca 150e), glow plug module didnt need replacement. 
I had one especially rough start (before the costly glow plug was replaced) during which some short bang under the bonnet happened.
After that, power was limited to cca 60KW. 
Checked the codes, swirl flaps actuator problem detected - lever broken (didnt actually mean that lever was broken) 
Checked the swirl flaps mechanism, everything was working ok during ISTA testing, lever was intact, flaps moving, although the procedure actual position for closing was few milliseconds slower than desired position. 
Few resets of adaptations later, code came back every time after driving for few km.
Technician suggested to clean gunk off the flaps. Did that using chemical bath and using few brushes, flaps moving effortlessly now. Put all together, reset adaptations, code came back few miles later. 

Today I found "voodoo" solution on the web, apparently screwing a screw into the swirl flaps motor will help, tricking the computer for the offset resting position of the flaps. Link to the pal's post of the original idea attached in notepad file. There are pictures how to apply the screw so I dont want to take credit, but its brilliant.

Tried it, so far I drove 5km from the shop without the code popping up, full power of the engine is restored, but will need some more testing. 


Remaining issue: after tuning the engine, peak power is inconsistent. 
If you put your foot down, engine reacts with full power (at around 3k RPM) for only a second or so, then drops power to cca 60KW for a second, then back to cca 90KW, back to 60KW, then to cca 100kw, back to 60kw, then full power, and then it cycles between full power and cca 60kw. (all feels like you would be pressing the gas pedal and letting go each 500ms or so. Very weird. 
I tried cleaning MAF sensor with MAF specific cleaner, didnt help. 
Restoring original tune would help, because this behavior is present only when I request more power then was stock. Lets say stock power was 85KW, so if I press the pedal reguesting anything below 90kw, the behavior is not present, it is only present with the foot on the floor, requesting 100kw and above. 
Not planning to restore the tune, as the engine is capable of much more, just need to fix the problem. 
Will try to find other solution and I'll let you know, as well as how the screw for the swirl flaps is holding up.

[johnnymato]

Reporting back on the swirl flaps screw fix - 100km later, no code popping up, so I declare it a success.
Inconsistent peak power still remains to be demystified though.