Time for an update:
I ran the car for some hundreds kms in the last days (been to WRC championship in Germany last weekend. None of those cars tougher than ours'
!! And Tina still in good shape, even in a Skoda eek! !). I gave a total of 3 bottles of injector cleaner (wynn's and liquy moli) along with approx. 90 liters of fuel. Unfortunately it didn't resolve my problem: the engine's still running on three cylinders, but...my impression is that although still running on three cylinders, the engine is running a lot better than before!!!
SO IT COULD BE A VALUABLE THING to use injector cleaner if you're experiencing performance problems, or even to clean up injectors that are already messy and could block one time!!! Maybe it could solve the same problems that often lead that damned lambda probe to be suspected?????!!!!!!!!!!!!! Let us know, if somebody experienced/experiences some wonderful results with injector cleaner in general!
- checked resistance value of all 4 injectors (at round connector located at right side of power steering reservoir): all ok (gracias Sebastian!)
- checked "clicking" of injectors (thanx JB!!) at same round connector running to wires from battery (same thing as doing it directly at the injector pins. saved a lot of time. thanx again Sebastian!!). The result: all 4 injectors are clicking, but the one from my non-firing cylinder less strong!!! Unfortunately i don't know how the suspected injector clicked before using the cleaner.
Gonna do some other diagnostics on the injectors now. Peter & Chris: I think i already tested that, i even bought a new set of plugs and leads. But for sure, i will test it again!!!
Last question: What manufacturer are the injectors on a 1992-Q4? I guess their type no. is IW 058 as MaxiBosst pointed out before!?