My father in law has a 2010 Accent that is having a weird timing issue. When you start it up it will idle fine, but as soon as you get it up to 2000rpm it will start dropping and bouncing around then issue rough until you turn the car off. It's not throwing any codes and practically everything relating to fuel and ignition have been replaced. At this point, minus the block and trans, it's pretty much a new car. At this point neither of us have any idea where to look other than getting the computer reflashed and seeing if that does anything. Any insight you guys have would be greatly appreciated.

 

When was the last time the fuel filter was changed?

 

I'm pretty sure it was one of the many parts he's already changed. But I'll have to double check. Not sure if I mentioned this in my first post, but all of this is with the car in park. So no load is on the engine.

 

Something to consider,
Random changing of parts can create addl problems, so good idea to refrain from doing that.

Instead of changing parts might be a better move to read up and understand how some of these things work

Higher RPM does require addl fuel and if not available, engine will not increase RPM because addl air is allowed in , but not enough addl fuel and it could result in these same symptoms.
Suspecting a problem component and verifying it's malfunctioning is what good mechanics do.
Just replacing good parts can get expensive and disappointing., hopefully we can save you some time and $$$.

Valve train problems can produce some symptoms as described, but replacing all the other parts is not always the best thing to do.
If it is determined to be a valve timing control problem , there are a few things that can be checked to help verify that too.

Did this problem appear a short while after purchasing fuel?