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Misfiring/Hesitation issues.

sakman
5

Asked by sakman Jun 19, 2008 at 11:50 AM about the 2007 Hyundai Sonata

Question type: Maintenance & Repair


I love my Sonata so far, but the big issue and only issue (other then MPG, on the low end) is I have had my "Check engine light" come on and blink 3 to 5 times.  I took in under warranty service and was told it was the Oxygen Sensor.  Replaced and all was well.  I have had this issue re-occur 3 more times.  The car runs at a rough idle as the check engine light flashes and then it may be 1/2 day to 4 days the light will go solid and stay on, but run good.  I was told the light needs to be on when brought in, or they will not be able to diagnose the issue.  Why is this.  The computer does not log histories??? I was told another time that it was a mis-fire code and was most likely bad gas.  How can I confirm or rectify this?  Is anyone else having similar issues?  Please advise or respond with any other thoughts or suggestions

23 Answers

Adam Morgan
3,635

Umm where do you get gas.... I would try somewhere else.... If you've fouled out an O2 sensor and are having misfires it's possible that you're getting low quality gas... Also make sure you are buying the proper grade of gasoline... A dealer should have the computer that will read all major codes that have ever posted since an ECU flash, however if it's a small dealer they may only have one of the crappy little hand held OBDs that you can borrow from any parts place, and most of those can't read pending codes... Additionally many will charge a diagnostic fee to use the nice computer.... Speaking of which does anyone know what software they use... I have a OBD tool that connects to my laptop PC but has fairly basic software and allows only the basic scan read reset features of a handheld.... Anyone know where I can get software to read ABS, and make/model specific codes... But see if it's the gas... If it isn't I'd check plugs and wires... Could be a wire popper loose or fouled plugs(considering the O2 went out already). Valve cover gasket could be leaking into the plug wells ect... These are just the easiest things to check and are by no means the only possibilities. If your light stays on take it in and get it read.

1 out of 1 people think this is helpful.
papa
Not Active

if you are having a ing misfife problem have the coil pac checked.theese are known to be faulity from the factory,as our mechanic stated above you could have a bad plug wire causing the missfire,but a scan would not tell you this,only ing missfire,sugestion,at night crank it and see if you see what we call a lightining show,you will be able to see if plug wires are bad rev enging a little if bad you will see the wires throughing biue streaks.

jamesg
0

if you're still having the problem. just today i again took my '07 to the dealer. had already had the timing chain tensioner replaced due to some noise at startup and rough idle. ultimately they said there was an updated needed specifically to rectify this. would have thought of it, but it's running silky smooth now, shifting better, some power is back. dont know if it's just for an '07model,etc. but it's a possibility i suppose. good luck.

jamesg
0

made a typo. it was an update made to the computer. also, i had thought it was gas quality the whole time.

Geoff Jourden
145

The light doesn't have to be on to scan it, the codes should remain in history. Once you get the diagnosis codes that should tell you the problem, if it's misfiring it should also tell you which cylinder is missing. You can also check your wires by spraying them lightly with water, You should be able to see them spark out if they are bad. Also the sonatas had more then just 1 o2 sensor, possible they replaced the wrong one? You have 1 or 2 before the converter and 1 after the converter.

3 out of 3 people think this is helpful.
Bahbeet20
55

Having the same problem with my 2007 Sonata Limited. Took it to the mechanic, had the O2 sensor and spark plugs replaced. Everything was fine for a couple days, then boom, it started acting up again. Frustrating bringing it back to the mechanic as I work 40 miles from home. I also don't expect the dealership to be any less annoying with fixing the problem. This is quite annoying. I love the car, but I don't know hwo much longer I can deal with this. Have you got any answers on your end?

3 out of 3 people think this is helpful.
lisac
10

I have been dealing with the same situation for about a year now and I can take it anymore. The car hesitates after driving in a while. I have changed all the spark plugs, fuel filter all the knock sensor and I just changed the intake manifold gaskets car ran alot longer before hesitation started. Still have same problem, my next step in the 02 sensor. If you have not had the intake manifold gaskets replaced you may try that a leaky intake manifold gasket can cause the same problems.

1 out of 1 people think this is helpful.
Joe Finis Sr.
655

I have an '07 Sonata with almost 50K and so far (knock on wood) no issues at all, love it. I would suggest trying a different dealer? The check engine computer does store histories until cleared, them telling you otherwise makes me suspect their level of interest.

1 out of 1 people think this is helpful.
stamstc
20

this has been such a helpful blog. I am having the same hesitation issue on my '07 sonata Limited (just not running like it used to). Its at 46k. they just did a tranny flush and no change. Looks like noone has really found the "golden solution" to fix. Anyone have a suggestion as to where I should start?

1 out of 1 people think this is helpful.
stamstc
20

actually now that i read it more carefully, looks like the only "fix" that worked was jamesg, who had a good experience after they replaced the timing chain tensioner and did the software update. Maybe I will start there. Thanks all for letting me know it's not in my head! (that's how the dealer treated me)

1 out of 1 people think this is helpful.
SortPa
30

I have the same problem with my 2007 Sonata SE. Dealer did the software update on the computer, but on the ride home, the check engine light came on with the rough idling. The dealer is unable to tell me what is wrong with the car, but suggested I replace my spark plugs and coils. Of course the car has 65K on it so it is not under warranty. I went the Consumer Affairs route and Hyundai denied the claim to replace the coils and plugs. I had the dealer replace the plugs... the car is still running rough, but better. The check engine light is not on yet. The dealer tested the coils and said they were all fine and to hold off on replacing them. Does anyone have a better answer to whats wrong with the car?

Jeff Leeper
Not Active

the misfire and the O2 sensor trouble lights point to an intake manifold vacuum leak. have you had any of the air intake duct off recently, or installed an aftermarket intake?

2 out of 2 people think this is helpful.
Chase Sutherland
3,325

all of these issues can be directly related to a bad O2 sensor. if the O2 sensor before the cat is bad or fouled it will make the car run terrible and misfire. in order to trip a check engine light from a bad O2 sensor it must reach a certain point. they dont just come on if they arent 100% perfect. next time the check engine light comes on i suggest going to someplace like autozone to see if the O2 sensor is bad. they will tell you for free. if thats the case its a simple fix and its cheap if you know how to use wrench.

1 out of 1 people think this is helpful.
Chris Brown
5

I the check engine light is blinking, that means there is a severe engine misfire which would not be caused by an intake vacuum leak or an o2 sensor. Granted if your car is misfiring it can damage the o2 sensor because too much unburned fuel is going into the exhaust. You need to pull the spark plugs and take a look at them. See if any of them are wet, black or smell like fuel. That is a good indication that the cylinder is not firing correctly.

SortPa
30

I changed an air filter, but no other parts of the air duct system were touched. The car isn't throwing codes for the O2 sensor only p0300 and the occasional P030. The spark plugs were replaced 3 days ago... so far it seems better, but not perfect. If too much gas was being released into the cylinder, that could explain why my MPG seemed to go down a little.

Jeff Leeper
Not Active

P030 is an O2 sensor code.

1 out of 1 people think this is helpful.
Jeff Leeper
Not Active

Are you using a paper air filter or an oiled one like a k&n?

1 out of 1 people think this is helpful.
SortPa
30

Hmm... Interesting. If P030 is an O2 sensor code, then I take it P0300 and P0301 are related to the O2 sensor somehow?

2 out of 2 people think this is helpful.
Jeff Leeper
Not Active

P0300 is multiple cylinder misfire. Vacuum leak or bad/dirty maf sensor are the likely cause

2 out of 2 people think this is helpful.
SortPa
30

I am currently using a paper air filter.

1 out of 1 people think this is helpful.
oceantoocean10
0

Buy a new car, did you say your car was a 1956? this is a classic by now.

love2race86
30

I have a 2000 Sonata and its reading number 5 cylinder misfire. is this from the coil?

3 out of 3 people think this is helpful.
bigcornbread
10

Hi my 2007 Hyundai sonata is doing a code p2187 engine running lean at idle and will do the codes you all are having now but the problem is intake manifold gasket take carb cleaner spray around it while car is running it will idle up when it picks up the carb cleaner and you may even be able to hear the hissing sound it makes gasket 13 dollars and it can be a bit of a pain to put in.

1 out of 1 people think this is helpful.

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