20 Most Recent 1999 Hyundai Sonata - Page 6 Questions & Answers

I would check your spark plug wires as well. One could be faulty. But if the RPM's are fluctuating up and down, theres a good chance that the engine isn't getting a consistent air flow. Some things to check are your intake, Mass Airflow Sensor, Throttle body, and air filter. On the intake, check the hose that goes from your air filter to the engine, make sure there aren't any holes or anything abnormal to it. As far as your Mass Airflow Sensor, some times if you go without changing your air filter for a good while, debris and dirt will pile up on the sensor causing it to send incorrect signals to the computer for the engine making it take in too much or too little air to the engine. You can solve this by getting a can of MAF sensor cleaner and following the instructions on the can. BE VERY CAREFUL if you choose to pursue this troubleshooting option because that sensor is very sensitive and can break easily causing you to have to buy a whole new sensor. Buying a new sensor should be a last option after everything else has been tried. As far as the throttle body, make sure that the wire that controls the air intake isn't broken or frayed, which would cause it to operate incorrectly. Additionally, check your Throttle Positioning Sensor, and Idle air control valve. The Throttle positioning sensor tells the computer how much air to allow into the engine when accelerating or idling, and the Idle Air control valve does a similar function by regulating how much air flows through the engine when in idle (rest). And finally your air filter. It's good to change that out pretty much every oil change to maintain a clean airflow to the engine, which is a huge factor to its performance and fuel economy. Further troubleshooting options would involve your spark plugs and spark plug wires, you may have a faulty spark distributor. Its that box that the other end of the wires are connected to, it is what sends out the current to the spark plugs. And after that if it gets this extensive, you may have a problem with your fuel lines or fuel distributor. Most likely it has to deal with air flow because I had to solve a very similar problem on my friend's Mazda Protoge. If you have a check engine light, next time you get the vehicle to start, bring your car to an auto parts store and see if they can read the codes that the computer is putting off that signals what the problem is. It should give you the exact location of the problem with your vehicle. I hope this bit of information is useful to you, and I wish you good luck.

honestly no idea unless i could have a good look myself ,i cannot even think of what he has done to the wiring ??

Go to www.hmaservice.com and register your vehicle by VIN #.. you'll then have access to wiring diagrams, shop manuals, service bulletins, campaigns, illustrations and procedures, etc.

Is the transmission in NEUTRAL?

it is most likely the control on the dash

Have your charging system (alternator) tested. Sounds like a charging system problem. Hope this helps , TJ

Electronic Stability Control (ESC)

You don't need engine specs, just a part number. Autozone.com

because of copy write laws I cant send you the diagrams but you will find what you need in the referance section at your public library.Hope this helps you

i think you have mis understood the garage ,oil on leads will not help the car run right either as it will short them out .But you have to watch some shady pratices from dealers who like to milk the golden cow,by saying that before they can rectify one thing they have to rebuild the car .But yes a leaky rocker cover gasket could stop the car if the plug leads were wet enough with oil.

say about 200.00 dollars

Hi, I wouldn't open the door just yet. Not sure what you have now that someone has "made it to work," but below is the stock setup. I'm assuming the fuse that is blowing is the 10 amp fuse #16 in the dash fuse box. There is a relay in the passenger compartment relay box that you need to check. First pull the relay out and put a fresh fuse in. Does the fuse still blow when you turn the key on? If yes, suspect the fuse box itself has a short, or the wiring is not as it should be. If not, suspect the relay has a short--try another relay (you can borrow a similar relay from somewhere else in the car for troubleshooting). Please try this, and we'll go from there.

It's either the horn switch in your steering wheel or the relay that powers the horn.
Relays are usually on the firewall or fender wells, both under the hood.
Relays plug on and off easily. Any autoparts store will tell you if you have one on your model.
If it is in the steering wheel, best not to mess with it, if you have airbags.
If no airbags you can try to remove the cover in the middle of the steering wheel and
check the horn switch there. Sometimes these are hard to work on and because you look at the steering wheel constantly, it is a visual bummer if you cant get it back right.
If you want it working correctly, have a shop fix it. If you wish to make it work
yourself, you could go to Radio Shack and buy a Momentary contact switch with
at least a 5 amp rating. All you need to do is connect one side of the switch to ground
(any metal screw that screws into metal-no plastic!) and connect a wire to the other side
and run it up, thru the firewall to the horn. Figure out which wire is the negative on the horn and
unplug it from the horn. Connect your wire to the horn terminal. Now the horn should only work when you press the switch. If the horn has only one wire and it is Positive you may have to run a hot 12 volt
wire from the switch to the horn. Be sure to add a fuse to this setup at the input to the switch. You can
find a 12 volt positive wire under the dash that has power when the key is on. Tap it and add the fuse then connect it to the switch. Run another wire to the horn and you are done. It may sound complictaed but it's not and it will work.

The fuelpump relay for a 1999 sonata is located behind the center console below the radio. good day.