2000 Sonata "mysterious massive power loss"

[00SonataOwner]

Hi everyone,

Any ideas what could be going on? I've got a 4-cyl 2000 Hyundai Sonata with 75,000 miles doing some strange things. First, in the morning when I start it up and put it into drive, it occasionally will not immediately accelerate when I hit the gas, instead waiting about a second and then jumping forward to catch up to the gas pedal. This only happens the first time I start the car each day, and only happens the first one or two times that I hit the gas - the acceleration seems fine for the rest of the drive.

This first problem led me to get the car looked at. The O2 sensors, spark plug wires, and spark plug cylinders were all replaced. This fixed the problem for about two weeks until it came back around. At this point, I replaced the mass air flow sensor with a used one and the problem went away. This happened two months ago, but I think the problem might be back.

When the spark plug cylinders were replaced, the mechanic said that the vehicle was also experiencing a second problem, potentially more serious than the acceleration: sporadic massive power shortages of which he couldn't find the source. Since the car seemed to be working fine (and the check engine light went out) after the mass air flow sensor was replaced, I figured this problem was fixed too.

However, I think that the power problem is back. The check engine light turned on last week but turned off earlier this week of its own accord. More tellingly, every once in a while while I'm driving, it seems as if the engine stops and then starts again after a split second. If I am stopped at a light when this happens, the car might stall or it might just shudder a bit until the engine kicks back in. If this happens on the highway, the car acts as if power to the engine has been cut for a split second, with the effect being that it feels as if someone hit the brakes and then immediately hit the accelerator.

Any ideas? Thanks!

[jvonier]

voltage regulator maybe? I had that kind of prob on an old truck of mine, turned out to be the positive battery cable was loose.

[stodge]

If the engine light came on take it to the dealer to see if it stored the code.

[quickywd01]

Many people with these cars are having problems. Also some people have problems with their idle, me too. I have a 1999 v6 and after the transmission warms up (1 hour) the transmission will drop into 3rd gear and stay there until I shut off the car and start it again but then it will happen again. About my idle, sometimes my car starts to shake like its going to stall but the idle only fluctuates about 50rpm and when I rev it slowly or quickly up to about 2,000rpm the shaking is there. I wish I had your problem instead of my transmission problem. Did you check under the hood to see if the throttle cable is binding, pop the hood and while the engine is off, grab the throttle and twist it slowly to see if any binding occurs.