Car Hesitates/Bucks when accelerating and switching gears.

[chubbybistro]

Help! In the last 2 weeks it has gotten worse. When accelerating/switching gears, the car kind of bucks. It's the same feeling as when you are running out of gas. This is really troubling. Does it need a tune-up or is it something more serious?!!

[jaffo]

Originally Posted by chubbybistro

Help! In the last 2 weeks it has gotten worse. When accelerating/switching gears, the car kind of bucks. It's the same feeling as when you are running out of gas. This is really troubling. Does it need a tune-up or is it something more serious?!!

Hi, my girlfriend has a 01 Sonota with the same problem. I changed the spark plugs, this one took the special NGK plugs at $20 each. The problem went away for a little while but now seems to be comming back. Just wondered if you found a cure? I thought it might be the tranny fluid and filter need to be changed?

[anaree]

Ok I have a 2001 and my car does the same thing. If im sitting in traffic and step on gas to go and then release my car coasts and then bucks forward and it seems to be around when doing 15-20 mph. I have had it to dealer and they tell me nothing wrong it and its normal. In my opinion its not normal for a car to buck forward, especailly sitting in traffic and i almost hit the person in front of me cuz of it. So if you find out whats wrong, please let me know. I plan on taking it back to the dealer but need car everyday right now and cant leave it there for days until they figure it out.
So any help as to WHY they are doing this would be appreciated!!!!!
Thank A Bunch everyone and HAPPY NEW YEAR!!!!!!

Anaree

[aarreola70]

I own a 2000 sonata gls 2.5 v6 and we share a similar problem mine also bucks after it gets warmed up. It use to also down shift from 4th to 3rd gear
while drive at highway speeds. I had it serviced at a transmission shop (change the fluid and scraped the pan). This solved the shifting problem,
however the bucking continues. There have been many error codes so I changed the sensors that were suspect such as input sensor, output sensor,
speed sensor, and the last is the crankshaft sensor which I suspect will solve my bucking problem. Like other Sonata owners have written the rpm drops to 0 and shoots back up to where the car should be and it is during this drop that the vehicle dies for a split second and then resumes. After speaking with my mechanic buddy who is certified he tells me replacing the crankshaft sensor would be his next guess. So I will let you know how it goes. I just have one ? Where is this crank sensor and how do I get to it? if any knows I would appreciate some in depth instructions.

[armyers]

We had this problem too, and after many visits and arguments with multiple dealers and Hyundai complaints department, transmission service, many sensor erplacements, eventually convinced dealer to swap the transmission computer with another car in the yard and the problem disapeared! Has been OK for over 12 months now, but don't say it too loud

PS the transmission computer has a fail-safe mode taht locks the transmission in 3rd, whter you stopped at lights or driving at higheay speed