drk: is this answering to you ?
The engine check light is turning on only when :
1 - I release the throttle @ 3000rpm
2 - I push down the throttle to the maximum
The rest of the time, the light is off and the engine work fine.
Hi kaou
My ecu issue started off similar to this, got gradually got worse.
If you use Pro Tune in gauge view you can run the motor and reproduce the actions that usually cause light to come on.
You then look for any of the readouts to flash red. This means they in "fault" even if they don't register.
For me it was the over-voltage readout which went up to 18 volts when blib accelerator above 2500 revs.
I used a screen recording program and made videos of the live gauges whilst driving. This way you can play back and see what's happening.
I don't have the files on the iPad, but when I can I will post a couple of stills and short video if you are interested.
Eventually the choking at low rpm got very severe with masses of black soot ex exhausts. Replacement ecu was the fix
