I have retrofitted LED bulbs in my footwell lights.

The bulbs are very simple: (+)---(1N4007 diode)---(resistor)---(LED chips)---(-).

The problem is they make a stupid flicker when I start the engine:

https://www.youtube.com/watch?v=kmerBDqv7Pk

Any ideas to fix this?

I recoded them to LED using VCDS but no success.

I understand that such a small drop in their supply voltage is not visible with halogens and very visible with LEDs.

The question is how to fix it.

Will a 10-100 uF capacitor (wired in paralell with one of the lights) cause any problems to the ECU? I think that could solve the problem.

Update:

I have tried some caps up to 4700 uF, wired in paralell.

They failed to stop or even smooth the flicker efffect on engine start. :(

The only effect was a slower fade out of the bulbs (ie. when changing brightness in menu) due to the stored energy.

Bad news :(

My led bulbs are totally dim below 9V so the voltage drops that much on engine start.

What battery do u got? My stop / start funktion did some spooky things and the leds started to flicker. I've now change to a "Branded" battery and now it works like it should.. Only the trunk led flicks but thats due to bad ledbulbs from ledperf..

Have these been wiring back to the BCM and coded with VCDS?

Just to let you know that coding them to LED will have no affect on flickering, only error reporting. As far as I'm aware only 2 lights on the car has a power buffer to prevent flickering / shut down whilst cranking (xenon headlights + LED DRL on vRS)

You could try larger capacitors?