>>531750996
It was a terrible plane in both avionics and flight performance, the then brand new J-10 was put in a joint exercise against J11s and not only the J-10 won, one J-10 managed to beat four (4) J11s in a dogfight at the same time.
The radar was bad, the rwr was bad, everything except the engine (got replaced anyways) was bad.
Situation with J-11 was so terrible that it made China sever the relationship with Sukhoi entirely and take on development of the J-11B with fully domestic parts and avionics with no Russian involvement at all.