Hyundai Repair: Sonata Tapping noise, spark plug wires, timing belt replacement

Question
QUESTION: I have 2002 Sonata, 79000 miles on it. Since my tech replaced timing belt, there is some tapping noise comes and also when its idle, it jerks. Dealer said the following codes:
P0455,P0302/P0300. Dealer says to replace spark plugs, which I did, but still jerking doesn't go away. the EVAP leak (P0455), they can not find any leak. I live in MD, does warranty covers timing belt change?
Thank you
ANSWER: Your warranty doesn't cover replacing the timing belt as maintenance.  As long as your tech replaced the timing belt with a factory Hyundai belt, the coverage on the belt will continue (as long as you're the original owner) until you reach 100,000 miles (presuming you reach that within  four years of replacing the timing belt).  Hyundai cannot of course warrant problems with your tech's workmanship or a part that isn't manufactured or distributed by them.

P0455 can set due to the fuel cap being off, loose, or improperly installed.  If they couldn't find a leak, then I'd suspect that the problem was likely with the fuel cap.  With the scan tool, the dealer can command the engine control module (ECM) to test the evap system for leaks.  I'd suspect they've done this and no leak was found.

P0300 and P0302 are misfire codes and are consistent with the jerking at idle.  Did you replace the spark plug wires when you replaced the spark plugs?  I'm surprised the dealer didn't recommend this as well.

---------- FOLLOW-UP ----------

QUESTION: Thank you for your quick reply;
Yes, I have changed wires and plugs, Dealer couldn't find any leak either.  

Answer
Okay.  We'll need to figure out whether the jerking is related to the misfirre codes or whether it's something different.

I presume the check engine lamp was reset when the plugs and wires were replaced.  Is it on again?  If so, do you know the trouble codes currently stored?

I also forgot to mention in my previous answer that the tapping noise could be related to the timing belt replacement.  You should take the car back to the tech that replaced the timing belt for him to inspect.