Officials from AVIC clearly stated that China will make it's own jet engines for J-10 and J-20 models. Jet engine is a bottleneck in Chinese aviation industry. That's why they have imported the Russian Saturn AL-31 engines and installed it to J-10s. If it wasn't the case than J-10 will probably be around in 2015 which would be very funny and humiliating.
"During the first phase, which will conclude by the end of 2015 if everything goes well, we will strive to ensure our air force's aircraft be equipped with proper engines and to lift our development capability to that of the developed countries' level in the 1980s. The second phase will witness us substantially narrowing the technological gap between developed countries and us. And by the end of the last phase, our engines will be as advanced as theirs."
I can't post the source as link since I didn't fill the message quota to post it. But it's a news from chinadaily and if anyone interested I can send it from private. As soon as I post 15 messaged I will edit this post and put the link for the source.
From this official announcement we can understand that in 2015 China will have the engine technology to fly a 4th gen fighter which is J-10. By 2020 they will have the technology to fly a 5th gen. fighter which is J-20 and J-31 and if everything goes as planned they will have the jet engine to fly a 6 gen. fighter by 2030.