Rough idle and poor performance, especially under load. HELP!
 

Hi guys,

I just got an 02 Sonata GLS w/ a V6- 110500 on the clock. It's a great little car, minus the idle issues! So, I was driving home awhile ago and was going about 45 and began to speed up- the engine began to sputter and struggle to get up speed, threw up a check engine light, and really had a really rough idle when I stopped. Then- as quick as it came, the check engine light went off and the car ran fine- albeit a little rough.

Fast forward a few days later- I had the plugs, oil, vacuum lines, intake and valve cover gaskets done- as I don't think any had been done for a while. It ran GREAT for about 2 days- then the issues came back with a vengeance!

Now, the car seems to miss at idle, but not too badly if it is in park or neutral- as long as it's not under a load. Yet, it idles SO badly when the AC is on and I come to a stop, and when I turn the AC off- it still runs badly, just not as rough. When I go up a hill or have to accelerate- it tends to bog down around 2000rpm, the whole car is jerky. I cleaned the MAF and the intake air filter and replaced the pcv but I'm running out of ideas.

At this point- I am not sure what to do! I'm thinking of getting the wires and coils done, and then moving on to the fuel filter/pump, maybe dumping in fuel injector cleaner, then go after various sensors- but I don't want to just throw parts at it. HELP!!

I've had several places hook up their scanners to it and everyone says that I come back clean. If it was throwing a CEL- it would be a lot easier! LOL

" getting the wires and coils done "
To clarify: you are not into diy?
If you are not doing it yourself it is advisable not to tell the mechanic: "replace this or that" because it is based on your level of diagnostics. And that results into something reminiscent of a shot in the dark. It is better to describe the symptoms to the mechanic and ask him for a proper diagnosis and an estimate for repair.
One thing you can do: While it is dark open the hood and idle the engine. Use a spray bottle with water and spray away at the ignition coils and wires. If you see sparks jumping replace the parts. Keep in mind that coil packs can also short out internally without displaying any fireworks for your diagnostic convenience.
Pull the wire off each spark plug individually. Each time it should result in getting worse. If it does not get worse with a particular wire than there is your problem.
Also: disconnect, inspect, clean all electrical harness connectors. Disconnect and clean all ground connections. The coil pack is likely grounded by way of the mounting surfaces and bolts. You may be lucky and solve the problem without further expense.

I would like to add a few items to the previous post,
If you tell the mechanic/technician what to do/replace and it does not correct the problem , you are still expected to pay for the work since he/she did as you instructed. Not always a good idea. A similar situation develops if you bring your own parts and ask to have the mechanic install them, if wrong or defective you are still expected to pay for the work done whether it corrected the problem or not ! Now the customer eats the bill for removing and changing the defective parts.

In the old days we pulled off spark plug wires to help locate problems.
That is not recommended these days because if that high voltage has no place to go it can/will damage the electronics on the way there.
Better, if that is what you want to do, is ground the spark signal and give it some place to go which will give the same result as pulling off the wire , but not do any damage to the electronics.

Thank you, hanky, for pointing this out. I was not aware of the potential harm to the electronics!

BTW: do you happen to know bluewind from the Ford forums?

I have never met bluewind personally, but have communicated a few times via posts. Always remember ,like us , couldn't resist "low hanging grapes" , lol.
How is he doing?
If you speak with him, remind him , nothing has changed, my wife still won't let me work on the wheelbarrow, never mind her car. Ya gotta know a good thing when you got it !

Hah!
You are talking to him!
Remember: "It is important to know the difference between precise and accurate - even if you are neither!"

So , you have a Hyundai in the fleet?

Yes, a 2013 Tucson. Has 80,000+ miles so far , no complaints or problems except the seats. If I'm good my wife lets me sit in it once in a while.The only thing she lets me touch is ,"Push to Start" button she had one drawn specially on the wheelbarrow. Anything else and Oh well ,,,,,,,,,
Great to hear from you again. They are probably ready to throw me off the Ford forum, missed ya !

So, you have a Hyundai in the fleet ?

Yes: 08 Sonata GLS 2.4L, 120,000 miles with history, actually her-story. The PO was a woman with an addiction to cosmetics. She even managed to burn out the switch of the make-up light on the mirror. She messed up the headliner with foundation and spilled mascara or another substance in the center console. We have the car now for 3 years. It's my younger son's car. I had it for the past 10 month while he is abroad. He'll be back next week. He may have difficulty recognizing the car because I detailed the interior and fixed a myriad of minor issues. Recently it developed an engine tick which makes me think the PO may have followed an extended and randomized oil change regimen.
My wife now drives 2010 Ford Focus. with only 60,000 miles. Since nothing goes wrong with it I have no reason to be active on the Ford forum.
You probably remember my issues with my older son's Mazda truck. I finally resolved that by using an OEM retainer clip in the quick disconnect of the hydraulic clutch. My older son does not need a vehicle anymore. Therefore we sold it.
I am driving an '05 Pontiac Vibe. What a lovely little box that is! I bought it because there is room for the dog in the way-back.

Good to hear from you. I recognized your handle and much enjoyable writing style.

Let's give this thread back to the original poster. I hope he will give us an update.