Just purchased a 2017 Hyundai Elantra Eco. When accelerating at low speeds, car starts to pulse and jerk. This happened several times. At higher speeds, I don't notice this jerkiness

I hope my car only has problems at 25 30 if it fine at low an high speed where is a problem at 85000 miles

All the above problems were happening to my truck, and the engine light never did come on. Finally changed the O2 sensor, and it runs like new again.

It almost sounds as if the rev limiter is kicking in.

Hi there, it could be a change of spark plugs will solve your problems. I'm driving one too but found that it jerked when accelerating. So I read up and presumed that the old plugs might be the cause. After changing new spark plugs, it doesn't jerk anymore.

check your weel bearing

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.

dear friend-plse look at the following:feul pressure,feul system,mechanical fault, ecm.these are all related to your problem.

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.

The Hyundai online shop manual and my newly arrived Hyundai shop manual kept pointing to the coil as a possible problem. While preparing to check coil continuity I discovered the pigtail connected to the bottom of one of the coils was loose and the contacts were burned. This is the coil that supplies spark to plugs 1 & 4, the same ones that kept showing up each time the check engine light illuminated. After cleaning the contacts and making sure the pigtail was securely attached to the base of the coil I have had no further problems.