Hello All!

I have had my Hyundai 03 Elantra for 5 years and with 120,000 miles on it. Thats alot! I know. Just recently, about two months ago I went on an out of state trip and on the way back home my vehicle started stalling on the freeway. I was going about 65-70mph and then all of a sudden it would drop down to 20 mph and I would push the gas pedal down all the way. So I would have to drive on the side of the road and then it would pick up again. It did this for quite a ways until I noticed that I would have to let my vehicle rest for awhile and then start driving again with no problems. I traveled from Phoenix, Az to Fresno, Ca. It did it for the first couple hours until I realized I had to give my vehicle a rest every hour or so. When I got home I was told it was the oxygen sensor and I replaced it but the problem still persist. I had replaced the sensor in front of the engine but I also heard there is one by the muffler. I was also told it might be the fuel filter or I think the fuel injectors which is why my vehicle would jolt/stall. I also noticed that when my ac is on and im driving there is not that much force to driving but when I turn off the AC, my vehicle feels like it gets a boost and goes faster.

So I am stressed out and dont know what to do! Know one seems to know of the problem. I have taken it to a mechanic but they didnt know anything or couldnt find the problem. Has anyone had the same problem and has been fixed?

Thanks for your time and hope to hear from you!

 

First of all, a bad oxygen sensor wouldn't cause this kind of problem. The engine would tend to run on the rich side, which may cause a rough idle, but at speed you'd hardly notice more than your gas milage had badly gone south. You should take the car to a mechanic to connect the car to a code scanner to detect any residing errors. If you want to do this yourself, many part stores will loan or rent scanners for customer use. As you know, these intermittent problems can be a bugger to figure out if you can't easily get it to manifest itself.

It's either a loss of spark or fuel to the engine. You should try to check for spark if this happens again, but that can be tough if you are by yourself. To help diagnose the situation, I suggest you carry a spare spark plug and spark plug lead with in the car with you. When the car quits on you again, open the hood and disconnect one of the spark plug wires on the coil pack, plug in the spare lead and position the exposed end of the plug up towards the fire wall where you can see it under the open hood. Turn the engine over. If you see a consistent spark, the problem is most likely fuel. If you don't see any spark, then it's an ignition problem. At this point, you could try another ignition coil, but remember to plug the first wire back into it's original position. I actually used this method on a 93 Ford Tempo that had these very symptoms.

I'm guessing it is either the crankshaft rotation sensor going bad (no spark) or the fuel pump is going out. Both are problems that tend to initially manifest themselves on a hot engine, get worse with time and eventually fail. In my case, the Tempo had a failing fuel pump. Also, if the car has spark, you could then check for adequate fuel flow, but a hot engine on the side of busy road is not the best place to monkey with the fuel system even if you know what you are doing.

Good luck.