Critical point, and the answer based on all the defense dailies there are to read is "no". Their engines are based on what they've learned from the Russian engines they've copied, no secret to anyone I suppose, but since the Russian motors in most of their fighters still have their own problems, it's hardly surprising that Chinese copies end up being even more problematic.
I linked an article here last year regarding the SU30 fleet that India flies, and at the time it was written over 1/2 their fleet, 55% it was, were sitting with motors ripped out of airframes or just plain broken and not working, as the Russians were being extremely slow in actioning repair and replacement requests. Either due to politics, incompetency, or possibly both, hah (IMO). Hundreds of SU30 fighters on a daily basis at the end of 2015 were unable to fly due to engine related problems.
This is one area where the USA and the West is still well ahead of Russia and China, the reliability and performance of their jet fighter motors. As the article stated as well, the Chinese avionics leave something to be desired too, and they are a long way off from sensor fusion or any of the new whizzy things that make US/NATO pilots have a lightened workload while increasing lethality simultaneously.
Still, considering what the J20's likely mission will be, and that they are likely to be semi-disposable based on Chinese doctrine, I think engine reliability won't be as cripling a problem as it would be for other air forces. Going to on long range patrol/loiter or point defense attack missions to go after Western C3/ISR heavy platforms at high speed with a somewhat low observable platform is what the J20 will be all about, and despite their 'advanced' construction, they'll likely die by the numbers trying to close with these assets and kill them. I don't think China can expect that trying to get within range of AWACS, tanker assets, and the intel birds will be a cheap mission by any stretch. This is also why the new long range variants of AAMs like the Meteor, new Amraam version, and the Russian/Chinese very long range missiles are such an important facet of the future air war in the South China sea and the rest of the Pacific theater.