Hi there, I haven't been here for a while, also not done anything to my 126 in the second half of last year. The lambda sensor position I used in the back of the silencer seems ok, I didn't run it in closed loop mode but the readings I was getting from the wideband sensor were very stable and predictable.
I have heard comments that there is a lot of benefit on these engines from going away from the mechanical ignition and using something programmable. Since the car was made in poland at a time when I imagine the fuel quality may have been variable, I expect the ignition timing is quite conservative as standard.
My next mods will be to set up the programmable ignition timing. I may also replace the fuel injection with a later version that we have developed for motorcycles - more complex software with more functions, will also use a bigger throttle body etc. but needs a bit of work to get something to fit the 126.
Also need to make some suspension mods (I lowered it, now the springs go loose on full droop so I need to mod the shock mountings).