NEED HELP, My 2000 Elantra just started to Buck like a horse seems like. Well it is reacting like a spark plug wire is going bad where the car starts to jump or buck so to speak. I have new spark plugs, Cables, Gas filter, PCV valve, new timing chain and new oil and filter. The jumping happened before and after all was changed. The Car is at the Hyundai dealer and they have not been able to figure it out for 3 days now and I don't see them figuring it out any time soon. I can't say that I care for the service center in my area. Has this happened to any of you out there and if so what was it that was going on. I am pulling my hair out!

You didn't mention fuel filter, although it would have to be pretty badly clogged to cause this bad a problem. Other possibilities are ECU (My best guess) or fuel pump.

Well, I did replace the fuel filter when it started happening before and the old one did not seem that bad. ECU...I am going to have to check that out but wouldn't the onbaord computer tell the mechanic that when they plug into it? According to Hyundai the computer does not show anything wrong but it does the same thing to them when they test drive it. I will check out the fuel pump as well. Thanks for responding.

have the same prob dude. 99 lantra wagon spent most of this last (australian) winter at the local mechanic getting checked out, had fuel filter, throttle body and everything else changed/cleaned. Made no diff at all. The plan now is to wait for the problem to fester and "hopefully" get worse so that it will show up on diagnostics, because apparently hyundai diagnostic and computer systems are dinosaurs compared with the rest of the car market. Interesting to note that there are more people on this forum alone having the same troubles that you and I are having; so it's reassuring to know we're not alone

Just joined here and saw this post. I had a similar but not exactly the same. Here awere my symptoms: For two days or so the car would not accelerate froma stop right away. I figured it was bad plugs and made a mental note to get it fixed. Then when I was driving on the highway from work the car starting revving and bucking wildly. At first I thought it was the transmission. the RPM gauge would fluctuate from zero to over 4000. Sometimes I lost power entirely and had to jam the gas pedal and then in a flash it would rev to the top range. It was terrifying! I was on a tollway with no exit for 12 miles and construction was blocking most of the shoulder so I got in the right lane and tried to manage it. Once off the highway the symptoms continued, no power at all then bam! it would accelarate. Drove directly to the dealer. They determined quickly it was the throttle control module. The guy said it was common and he gets several 2000 Elantras each year with the same thing. Since then, hasn't happened again.

Hello,

I have been having the same sort of problem...I am getting the computer changed as we speak...considering there is not check engine light coming on it is very possible that it is the computer itself...not a cheap fix by any means...but if you can find a used one your set...mine only acts up when the engine get's hot...

there have been a few other posts about this...mind you I have a 97...but as deano said it is a re-occuring problem

never heared of the ECM failing that often, sounds more like a CKP, AFS or TPS sensor problem.

well if you can hook up the diagnostic machine and actually get readings from the computer then it's not that...mine was definetly shot because they couldn't get into the computer...whoever own the car before me thought they knew what they were doing but screwed it up so bad it isn't funny...

I just got a call back...after they got the computer hooked up and could actually get readings from it, it turns out my fuel pump was only pumping out 25, when it was suppose to be pumping out 45...I am getting that replaced now.

and I have replaced/checked the crank position sensor, and the throttle position sensor...I am assuming by AFS, you mean the mass airflow sensor? I have replaced that aswell...although I don't beleive the new one(I got it used) is working properly...either way, in my case, the pump isn't working properly...hopefully that's it...

This post has been edited by Hinsey8: Jul 18 2006, 08:31 AM

I had simmilar problems with my '97 Elantra... in and out of the shop, lots of parts replaced- new fuel filter, new PCV, new injector, plugs, cables....

turns out after everything there was a loose connection! Behind the glove compartment there's a board that connects to the fuel injectors and a connector came loose, causing an injector to fail occasionally and the whole engine to go outta whack. Lots of error codes were generated that sent the Hyundai mechanics on a replacing spree!

I'd reccomend checking the fuel injection electrical system, or bringing the car to a reputable independent mechanic... the dealer guys seem to just replace whatever part is generating an error code or being damaged, instead of actually troubleshooting the problem.

good luck!