I recently bought a 2004 Hyundai Sonata 4cyl with about 65k miles. In the past few months I’ve noticed that it likes to sputter and hesitate at times, mostly in lower gears when I’m not accelerating hard. At highway speeds it’s mostly fine. It’s also fairly random - some days it’s really bad and others it’s fine. Also seems worse when in reverse. I don’t think the plugs have been changed so that’s one idea, but I’m wondering if it’s a bad fuel filter, exhaust manifold leak or something else. It’s not throwing any codes (and yes the light works) and it has never stalled completely out. Any ideas?
Check the owners manual for the plug change interval. If they are past due, then change them, but there is a good change that they use platinum or iridium and are good for 100 to 120k miles.
the manual has it as part of the 60k service and they are the fancier plugs. they also recommend replacing the timing belt but I will just have that checked and not replaced if it’s in good shape.
Take your pick - this problem could come from lots of things so you just do the basics. Plugs & wires, fuel & air filters at minimum. Check for vacuum leaks, including intake manifold gasket & intake snorkel. A cleaning of the MAF sensor & throttle body would be good.
If the timing belt is due for service it should just be done. But if it was a problem the car wouldn’t run at all.
I would strongly advise not delaying in getting the timing belt changed on this car if it’s the original belt. It actually has two belts; a main belt that syncs the crank and camshafts and another belt that drives the balance shaft. My daughter has an 04 Sonata with the same engine, and her balance shaft belt broke while she was driving the car, taking out the crank position sensor in the process. If the other belt would have broken it would have caused damage since this engine is an interference design.
The Hyundai technician at the dealer that repaired the car (she was stranded more than 100 miles from home) told us that the rubber compound used on these original Hyundai belts was suspect, and that he had seen A LOT of breakages. He advised changing early, like every 40-50K miles. You could be on borrowed time with one of those belts.