My 2000 Sonata (2.5l) idles smooth when in P or N. In gear it seems like it has a miss (though it never stalls). If I apply the gas slowly, it will accelerate just fine. Too much gas though and it sputters and shakes up to a certain RPM. Around 1500 RPM when cold and about 2200 RPM when warm everything smooths out and it runs fine again. No problems at all at highway speeds. The MIL is not on and there are no codes. Can anyone point me in a good starting direction?

This post has been edited by SoulRebel: Oct 10 2008, 12:01 PM

:00000732: Soul!

Amazing that you did not get the Malfunction Indicator Light (mil).

Let's see....2000 Sonata with the early 2.5 liter Delta, 8 years old, probably 120k miles. Bingo! When was your timing belt last changed? You can remove the upper timing cover to inspect with just a 10 mm nut driver. Your car sounds like retarded intake timing maybe by 5-7 degrees. You will need a helper to slowly rotate the engine crankshaft bolt Clockwise while you inspect for broken or missing teeth. If you are at or over 120 k miles, you should replace the timing belt anyway.

If not, you can always change plugs, air filter, and ignition wires.

Byron

My 2001 Sonata is doing the exact same thing. It's most noticable when shifting to second gear. If you give it too much gas it lurchs, if you back off it stops. Car has 80k on it and has had a new timing belt withing the last 10k miles. It seems to be getting worse!

I just did a timing belt this past weekend. If you can't find a discernible defect in the belt, line up the timing marks.

Both cam pulleys have a white dot on them that should line up with a notch in the valve cover. It's slight notch, but that is how to line up for timing. If your tensioner is bad, it could allow the belt to hop a tooth and mess with your timing.. To make it easier to line up, I used a Sharpie black marker to paint the notches and I used it to paint the notches on the accessory belt tensioner.

Chris

COULD BE NUMEROUS PROBLEMS - COULD ALSO BE VERY SIMPLE LIKE DIRTY INJECTORS - A DIRTY AIR CLEANER WILL CAUSE PROBLEMATIC RELATED ISSUES. *HAVE A LOCAL MECHANIC CHECK THE THROTTLE POSITION SENSOR*.

GOODLUCK

Update: Plugs and wires. It was one of my first instincts but I was hoping it would be something a little simpler. Took about 2.5 hours to change them, which isn't all that bad from what Ive read on here. The plugs were about 50,000 miles old. When they were changed before I supposedly got 100,000 mile plugs. I was shocked at the level of wear on them. On 2 of them the side electrode was noticable worn away and on 2 others the center electrode was down to about half its original length. To the point that I didn't have a feeler big enough to measure the gap. They were NOT 100,000 mile plugs. Oh well, lesson learned. Getting the surge tank out of the way was not as difficult as I thought it would be. This site and hmaservice.com were invaluable resourses and I don't think I would have had the confidence to tackle it myself without them!