Hi. New here and of course in need of some advice. My Elantra 2012 has almost 150,000M and started to shake eventually when pressing the gas pedal (this was going for almost a year)... today after an oil change at the dealer they recommended to replace the spark plugs for about $300+... so I decide to replace them by myself...boom! Watched a couple of videos here and there and it thought I did a great job, until was the time to start the car. It actually started but when I press the gas pedal the revs don't pass over 1100rpm ever when the pedal is all the way down. I already restarted the vic...unplugged the battery to see if maybe the computer needs to restart and maybe autocalibrate the timing, checked on all connectors and wiring. I also double checked the type of plugs and are exactly the same type and reference. Does anyone has an idea of what can be happening or why I don't get get any power after pressing the gas pedal? Did I miss any step maybe? Thanks

Hi Martin....I will answer your post with a series of questions to hopefully help you out.

1. At any time did your check engine light come on? It sounds like the shaking your talking about was due to engine misfires. With engine misfires your check engine light will not stay on. It turns itself off after so many key cycles and misfires the PCM records.
If your check engine light is or was on take the car back to the Hyundai dealership and tell them to check for DTC (diagnostic trouble codes)chances are you have misfire codes stored in the vehicle DTC history that can be cleared and then the technician must "reset adaptive values". If a Hyundai Tech is working on your car then he will know what that term means.
2. Are you sure you connected all of the electrical connectors on the top of the ignition coils to ensure good contact?
3. Have you checked the engine oil level to make sure the dealer did not overfill your crank case?

Recommendations....
with 150,000 miles I will assume a major engine tune up has never been done....
- replace spark plug ignition coils as the Elantra's are notorious for these not lasting long.
- have the dealer conduct an EFI (electronic fuel injection) service to completely clean out your fuel system
- check and replace your engine air filter if needed, if the engine is starved for air it can limit throttle response.
- at 150,000 miles I would consider a complete timing job....timing chains, timing tensioner and timing guide....generally these parts should be replaced about every 50 miles or so depending on how hard you drive the car. Most people don't worry about this because of how expensive and complex the job is. It's important for your engine life not to ignore this.

Best of luck...send me a message if you have any more questions or need help.

Thanks for replaying back. I found a code that led me to check the air intake system and I remembered I replaced the air filter as well. I found out I left a damp cloth I was using inside of the air intake while I was air spraying the filter box and I forgot it was there. That went to the throttle body and that caused restriction of the air flow of course. So after removed it the problem got solved. Unfortunately recent challenges didn't let me do this tune ups and reparations at the dealer, so I'm learning how to be crafty with my car. Any help is always welcome. Thanks