Rough Idle with Detailed Explanation
SEAT Ibiza IV ST (6J8, 6P8)

Hi everyone. First of all sorry for bad english but i think I succeeded [laugh]
My car 1.2 Tsi CJZB engine 66 kw manual. First my problem is starts when engine get warm. Before that this rough idle sometimes exists just one times or two times when engine cold, so it is not important. When engine raise to 80-100 degree engine rough idle every 2 seconds. And yesterday i recognized when i watch oxygen sensor bank 1 value up to 0.9 dropping 0.1 value as its supposed to be. but when it is dropping to 0.1 then my engine do like misfire rough. But absoluetly not misfre because VAG-COM didnt count any misfire and there isnt any fault code. Some mechanicer do lots of thing like change spark plug ,coil, clear throttle and similar things like check the timing belt and timing, but everything okay. But i pretty sure my problem exist when oxygen sensor bank 1 dropping 0.1 . so what part is broken? (if i press clutch or turn headlight, there is no problem because car go to rich fuel, oxygen sensor 0.9 for electric) Thank you.