2001 elantra, check engine light comes on and I get a cylinder 2 misfire

P0304 is engine misfire #4 cylinder Several things can cause a misfire #1 electrical which you have covered #2 Mechanical Test engine compression is should be around 150 cranking and 120 running . internal valve train components can cause bad compression and the valves then self. #3 fuel injector can be the cause suggest swapping with a know good cylinder and see if misfire follows injector.

could be bad spark plug. or coil over plug is bad

Misfire could be a number of things:
a) spark plugs - change them if used over 15K miles - inspect/regap.
b) spark plug wires - change them if over 15K miles - inspect
c) ECM (electronic control module) - test with HEI (high energy ignition) tester.

The shaking tells me that the engine is running on less than its normal compliment of cylinders - the shaking is produced by the imbalance caused in the engine by one (or more) cylinder(s)
not firing at all.

The "Check Engine" light probably is coming on due the the misfire condition. Go to Pep Boys or
Advance Auto Pats, where they'll tell you (free) your codes causing the "Check Engine' light to be
lit - the code coming from your truck's computer will probably be one or more of:
P0300 - Random/Multiple Cylinder misfire detected
P0301 - Cylinder 1 misfire detected
P0302 - Cylinder 2 misfire detected
P0303 - Cylinder 3 misfire detected
P0304 - Cylinder 4 misfire detected
P0305 - Cylinder 5 misfire detected
P0306 - Cylinder 6 misfire detected
P0307 - Cylinder 7 misfire detected
P0308 - Cylinder 8 misfire detected
P0313 - Misfire detected with low fuel

P1354VVT System Malfunction (Bank 2)

• P0300 Random/Multiple Cylinder Misfire Detected
• P0301 Cylinder 1 Misfire Detected
• P0302 Cylinder 2 Misfire Detected
• P0303 Cylinder 3 Misfire Detected
• P0304 Cylinder 4 Misfire Detected
• P0305 Cylinder 5 Misfire Detected
• P0306 Cylinder 6 Misfire Detected
• P0307 Cylinder 7 Misfire Detected
• P0308 Cylinder 8 Misfire Detected

Probably bad plug wires. Start there and then disconnect the battery for 5 minutes reconnect and start engine to see which codes have cleared.

First you will have to make sure that you are getting spark at that cylinder. There are so many causes that will make a car misfire, and the correct diagnostic will save money. Camshaft sensor. defective injectors, not enough compression to that cylinder etc. have it check throughly before investing more money.

what can i do to fix the output speed sensor

P0302-Cylinder 2 Misfire Detected How do I track down the problem and fix?

do a compression test then do a combustion pressure test if all good computer is questionable

weeeeiiirrdddd. i have a 2001 hyundia elentra gls, and my third cylinder is misfiring as well. my car also revs constantly on idle and in between shifting. it will flutter between 2-3000 or it will just stay at 5000. i replaced my plugs and wires to no fix with my cylinder. autozone also told me that it sounds like my throttle position sensor needs replaced, but every part they try to sell me will not fit and they swear up and down this is the right part...