My 2004 Hyundai Elantra surges and jumps gears

Same as ALL vehicle issues

Put a scanner on it & check for codes
& look at data,don't use it like that, until
you know the issue

Have a shop drive it for 25 miles & record data
& wait for it to act up,then diagnose the problem

anything is possible with electronics. If you had the fault codes read first then you would have found out what put the light on in the first place. It is there to let you know that the CVPU has detected a problem that is detrimental to the engine and gear box and just to try to extinguish the light without fixing something is inviting disaster.. Once you have fixed the problem then use the code reader to reset the CPU to put the light out.

I would check the transmission fluid. It may need changed and the filter changed. Perhaps you are not getting a good spark from your spark plugs or coils. Has it been awhile since you had a tune up?

dealers will go deep in you pocket shop around ,you have some good mechanics out there that will do the job for cheaper

Your transmission fluid is dangerously low (tranny is dry). The pops & jerks are the transmission
internal components trying not to seize onto each other due to lack of lubrication and/or overheating.
Low transmission fluid leads not only to loss of lubrication but lots of overheating (of the tranny).
The loss of Elantra performance (speed tops out at 55), is caused by power loss due to friction inside the transmission. All your power is lost overheating the transmission (toward destruction), instead of
being transmitted through the transmission to the wheels.

The 2004 Elantra takes Hyundai SP-III Automatic Transmission Fluid, with 8.4 quarts used in a
total refill - but just 5 quarts at a fluid change. For How-to transmission fluid change instructions:

http://en.allexperts.com/q/Hyundai-Repair-815/2004-Elantra-GT-transmission.htm

www.autozone.com claims that 2004 Hyundai Elantra can take these non-Hyundai ATF's:
Lucas Semi-Synthetic Multivehicle ATF
Pennzoil Muilt Vehicle ATF
Valvoline Maxlife Dex/Merc ATF
Castrol High Mileage ATF

Your transmission is slipping which can cause a huge amount of damage both to the car and your wallet. Take it in for service as soon as you can.

could be afew things. vacuum leak, one dud HT lead, could be the water temperature sensor, O2 sensor, best to get it checked and get it read for fault codes

I had something similar happen. My check engine light never came on but i did experience the jerking between the 30 and 40 mph mark. Have your fuel injector checked to see if its dirty. Also have your fuel lines checked to see if you have water in it and have them check the transmission fluid. its possible you can be low. When I had the problem i did all 3 of these things. My car does not **** anymore. Also another problem could be your valve cover gasket.

MY 1999 hyundai elantra shutoff on the interstate when i took it out of cruise control and put it in neutal and will crank but not start.

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...