Sonata NF (2006-10) :: Idle Seems To Almost Misfire When AC Is On
Oct 1, 2011
When at idle and it seems to either only do it or is worst when the ac is on. the idle seems to almost misfire. Usually its only for a couple seconds less then a min. I have had my odb2 hooked up to it and its about a 25-50rpm drop but it keeps doing over the course of a few seconds. It hasn't stalled doing it yet and its done it for years! however today at the drive thru it was quite aggressive. Usually I give it gas and its not as bad or completely stops, sometimes is doesn't work at all. This time I just let it keep doing it hoping a CEL would come due to it being more aggressive then ever but it just evened its self out after about 30 seconds. Almost feels like there is a mild performance cam in the car....
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I've got a troublesome misfire in a 2007 Sonata V6, 70k miles, which I have been trying and failing to track down for a long time.
More than a year ago, the owner of the car complained of rough idle. When this was first mentioned, I looked at the car, she and I talked, and I concluded that she hadn't changed the oil in some 20k miles. ...... Nothing else seemed wrong. I changed the oil, thinking that what she needed was an oil change.
Some time later, I was in the car myself and all of a sudden felt a strong bucking. Must've been a misfire. I recommended taking it to the Hyundai dealer, thinking the so-called 100k mile powertrain warranty would cover whatever it was (it didn't but whatever).
We drove it to the dealer. The dealer firstly informed us that the CEL had burned out, so we had missed some codes. The dealer further us the car needed new plugs and replacement of both upstream O2 sensors. Here was what the mechanic wrote:
"BETWEEN 35-40 PUT CRUISE ON AND WILL FEEL. CHECK AND ADVISE COMES AND GOES. MULTIPLE CODES STORED IN SYSTEM. ... P0300 RANDOM MISFIRE (ACTIVE), P0140 O2 SENSOR CIRCUIT NO ACTIVITY, P0154 O2 BS S1 NO ACTIVITY. WATCHED O2 VALUES AND FOUND ERRATIC READINGS. FOUND TSB 10-FL-012 SUGGESTING REPLACEMENT OF BOTH UPSTREAM O2 SENSORS. RECOMMEND COMPLETE SYSTEM TUNE UP FOR RANDOM MISFIRE. HOWEVER MISFIRE COULD BE RELATED TO O2 ACTIVITY.
So the owner went to a different mechanic and had the plugs, upstream O2 sensors, and one of the downstream sensors replaced. All OEM, I believe. ($$$!) (O2 sensor parts 39210-3C100, -3C200, and -3C400) Dunno why the downstream one was replaced, not my doing.
Following this, there was no real improvement. No codes either. The problem comes and goes, so maybe I thought it was fixed, but it has come back. Sometimes, it can be felt just slightly when the car starts cold. Other times, it can be felt just barely when driving at a consistent speed. Sometimes, the problem becomes really bad and jerks the car around. Other times, nothing.
What to check next? Coil packs? Intake manifold gasket? She never gets "top tier gasoline," but I would be skeptical that that's the problem. These are the top three suggestions I've heard.
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I have about 140,000 miles on my car, a 2006 Toyota Prius that misfires at idle when cold, and for the last 10,000 miles the engine has been using between 1 and 2 quarts of castrol synthetic 5w30 oil between the 5,000 mile oil changes. My check engine light naturally stays on constantly now and the engine also appears to misfire on acceleration also.
For the first 60,000 miles I had the oil changed at various places every 3,000 miles using nonsynthetic oil that was recommended in the car manual. Since then I have been getting the oil changed at the dealer where I bought it new and they switched to the synthetic oil, so I asked the service department, why the misfire? They said the new type spark plugs are very sensitive to oil burned in the firing chamber, causing the misfire. They told me to check the oil often which I do and the engine has never been more than a quart low.
Is there a spark plug I can use that is not as sensitive to the oil, or should I be looking for a junk yard engine or is it cheaper to have my engine taken apart and repaired. Will it damage the engine further to keep running it, there does not appear to be any smoke coming from the tailpipe.
From new I got mpg in the 40's now I am getting 33 to 34 mpg.
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When I'm driving and get above 50-60 I will get the Check Engine Light. Check the codes It shows 6 ---300, 303, 306, 300, 303, 306. When I slow the car down it is running rough, almost like it has a miss.
I reset the computer while this is going on and the engine smooths out and it runs correctly until I keep my pedal down and then it kicks the exact same errors.
Here's strange part number one: Once I get down to about a gallon or two of gas in the car everything seems to run fine. I have plenty of power, no codes and the car runs fantastic!
Strange part number 2: Very occasionally When I get in the car in the morning to go to work, the car is a bit difficult to start. When it finally kicks over, it is immediately running rough. resetting the computer with the engine running does not seem to stop the rough running. If I turn off the engine and let the car set for a bit it will start and run fine, with the exception of the first problem mentioned in this thread. There is no code while it is running rough, but when the Light kicks on as per the first issue mentioned, I have an additional code -- 335. This car has been excellent up until the last few months when this issue developed.
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I bought a 2005 3rd gen about 8 weeks ago and I love it except for one problem, a really bad idle/vibration through the cabin when cold starting, it improves when the engine is warm but is still noticeable.
It went back to the dealer where I got it and they gave it a full service, new plugs, oils and filters and replaced the transmission oil too after the check vsc and engine management lights came on.
The codes pulled showed a misfire on cylinder 2, the dealer said the service would cure all and sure enough no more vsc lights but the rough idle and vibration are persistent.
The car has only 78000 miles and I'm pretty certain a Lexus isn't supposed to behave like this.
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My moms has a 2010 Elantra with 30,000kms on the clock, and we have noticed since new when the vehicle is started cold in the morning it seems to run rough for about 30-60 seconds then stabilizes.
It's almost like it has a slight misfire, or slight fuel flooded from sitting overnight. Now if course we have taken it to the dealership twice for this issue and dropped it off overnight for a cold start, and both times they cannot re-produce the problem.......surprise.
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I did not get the specific cel code but its what the guy told me at autozone.
Long story short. Washed engine, let sit for about 30 mins. Car started with flashing CEL and was "puttering" and very rough idle. Drove home took intake off and replace with stock, took spark plugs out and they were not wet. Then let it sit for about 15 mins. Started just fine. No CEL at all.
The accent saved the CEL and the guy told me that Cylinder 1 had a misfire.
My question is, should I do anything now even though the car seems to be running ok?
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OK, car has 94K miles, never had anything done to it, and the timing belt stripped out a bunch of teeth and bent the valves, you know the usual deal.
Pulled the engine apart, and order a head gasket set and scored a low miles head from a salvage yard. I was told the engine it came from was running fine but had a damaged timing cover so they parted out the engine, when i got the head the timing belt gear was bent and cracked, but i couldn't see any other damage and all looked good so i put it all in, and after having some trouble getting good info on where the timing marks are suppose to go i got it all back together and went to fire it up, start and die a couple times, i figured it was the fuel system re-priming itself, car starts and is running rough, i give it a few small revs and above about 2K it seems to run fine, but has def misfires at idle.
While i was looking around the engine bay checking over stuff i can hear a definite buzzing sound coming from the injectors, which i can tell you isn't normal, and is causing my problem i believe. The injector plugs are pretty straight forward, so im pretty sure i have them in the right spots.
The CEL came on, and i plugged in my code reader but was unable to connect to the ECM for some reason. Are these cars can bus?
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2011 accent gs. We purchased the car brand new and it currently has roughly 32k miles on it. About a month ago the car started to misfire at an idle (in park and in gear stopped at a light, etc.). At this time, I purchased a new air filter, and a new set of autolite platinum plugs. Roughly 3 weeks later it started misfiring again. After a few internet searches it seemed as though some people don't like autolite platinum plugs. At this point I purchased a fresh set of NGK iridium ix plugs and figured that'd be the end of it. I test drove the car for almost an hour myself (the same night I repaired it) with no issue. On my wife's commute the very next morning it acted up again.
We took it to the dealer this morning, and I honestly don't believe what they're telling me. They are insisting the problem is with spark plugs. They say that the manufacturer recommends copper plugs only, and that would be step 1 of their diagnosis/repair which they want $130 for. At this point I declined their service, and they'll let me put copper plugs back in. They said that if it continues to act up to bring it back in after that. Ah yes, and during this whole time there has never been a check engine light.
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I bought a used Ranger a couple months ago and it ran fine when I test drove it but a week later it started having a misfire every now and then at idle.. I must have gotten pretty unlucky with the test drives..
The misfire comes and goes, it will run fine for a week or two and then it will misfire at idle for a week or two. It only seems to misfire at idle, the truck runs rough/shakes but once you give it a little gas and start moving it goes away. Usually it has a check engine light on from startup when it's misfiring and it goes away on days that it's running fine; it will occasionally misfire at idle with no check engine light. Sometimes when its running really rough the CEL flashes while it's misfiring at idle and I've actually restarted it real quick and the misfire went away for a bit. The engine codes that come up are misfire on startup and misfire on cylinder 4.
I've tried cleaning the MAF sensor, replacing the fuel filter, testing for spark and compression. Compression was 150-155 PSI on all cylinders, however, the compression on cylinder 4 is different depending on whether the truck is running well or not. When it's misfiring the compression on cyl. 4 is 90 PSI and when it's running fine it's 150 PSI. I'm not sure what could be causing intermittent low compression like that?
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After scouring through hundreds of threads on this forum (which is Awesome, BTW), it seems as if this misfire / rough idle thing is fairly common (which is scary!!). CEL is on steady. Had the codes pulled; P0301, P0302, P0303. At the recommendation of the mechanic, I had the plugs replaced...no improvement. He then replaced the ignition coils...no improvement. Just finished replacing the MAP sensor. This actually had a VERY temporary positive effect. However, after about 5 miles of driving, the misfiring returned. Took the car to the Hyundai dealership, and they acted as if they didn't want to fool with it. They referred me to a couple of local repair shops...????
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I know it is a random cylinder misfire code however I started my car in the morning and it was fine I moved it and put it back in my driveway. I started it up later and waited for it to heat up i came back outside 10 min later and my check engine light was flashing and my car was shaking like crazy you could tell the engine was misfiring like crazy. I had under a quarter of a tank but not empty yet. I shut it off and turned it back on and it was still doing it. I drove the mile to the gas station the way it was.
Under partial throttle it was revving to 4500 and over 5, had to let of throttle to make the car shift up a gear. I filled up and started the car again performed fine after that however the check engine light was solid now and still on. I went to my local mechanic and he read that code P0300. I changed my spark plugs that day and they were crap the original spark plugs I have 65,xxx on my car now. Car is smooth now. I cleared check engine when i saw him first and it did not come back on all day even before i changed the spark plugs later that night. Why my light was flashing and why my car was acting like that till i filled up?
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2006 F53 (motorhome) with 6.8L V10. Rcently noticed rough idle and midrange (under load) mis fire. Had codes on 2 coils. Replaced coils and put new spark plugs in. Did not improve and now detecting mild back fire.
Just completed compression test. 1=207psi, 2=200, 3=210, 4=190, 5=197, 6=200, 7=200, 8=170, 9=202, 10=208.
put some oil in #8 and retested at 225!
Other observations on #8. Engine has ticking noise chased with stethoscope to #8. THE new plug with 200miles, insulator going to electrode tip and everything inside combustion chamber is black. All 9 other plugs still look new out of box.
With the ticking noise I was suspecting valve but the compression test with oil jumped way up.
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Have an 06 F150 5.4 3v with no power. spark knock. rough idle. wants to die while driving, and random misfire code. Have replaced fuel pump, filter, coils and plugs. What to check next? Already thought of EGR - it doesn't have one.
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2006 F53 (motorhome) with 6.8L V10. Rcently noticed rough idle and midrange (under load) mis fire. Had codes on 2 coils. Replaced coils and put new spark plugs in. Did not improve and now detecting mild back fire.
Just completed compression test. 1=207psi, 2=200, 3=210, 4=190, 5=197, 6=200, 7=200, 8=170, 9=202, 10=208.
put some oil in #8 and retested at 225!
Other observations on #8. Engine has ticking noise chased with stethoscope to #8. THE new plug with 200miles, insulator going to electrode tip and everything inside combustion chamber is black. All 9 other plugs still look new out of box.
With the ticking noise I was suspecting valve but the compression test with oil jumped way up.
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I just bought a 2010 Sonata. It runs just fine while running and about half of the time while I'm idling. The other half of the time I can feel my engine sputter. At first it wasn't all that bad but it has gotten worse lately. What could be causing this?
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I have a 2006 Hyundia Sonata. I idles really bad like you pulled 5 of the six plug wires off when you put it in gear. Once you start moving a couple miles an hour it is fine. It is also perfect in park or neutral, not a hint of a problem. Put it in drive or reverse and it almost stalls.
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Lately I have been hearing a rattling noise from the bottom of my car, when it's in park I can barely hear it but I know its there, but when i put it in drive or reverse it gets worse. Could it be that the exhaust heat shield is loose? Or worse? I had my Tranny fluid flused at 142,000 mi i'm at 144,000.
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2007 Sonata V6 with 72K miles.
The car has developed a rough idle while in gear (i.e. when stopped at a stop light) and park (i.e. after I start the car).
It's starting to get a little annoying since I'm used to a very smooth idle.
I think this issue started within the last 2-3k miles.
Plugs were allegedly changed at 30k. A full tuneup was done at that time.
Wires are still original.
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In idle and driving the car sounds rough as if a pulley was loose, after checking no pulley was loose but problem still persists. Tried turning wheel left n right n noise didn't go away or get worse its a constant noise, what it may be? Crankshaft pulley? Idler pulley?
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2008 SONATA i4. The transmission started to whine a lot when first driven when cold, well transmission was replaced under warranty due to "pump failure"? I noticed that the loaner car I received for tranny replacement had a knock at startup so I called and told the dealership about it, they said it was the timing chain, it was a v6, oddly it didn't sound like timing chain to me, started after fast idle and went away within about 100 feet of driving.
2 days after I got my car back it would knock after I started it up cold when it came down off fast idle, and would knock for about 100 feet of driving or so, then the knock would disappear until the next cold start. exactly like the loaner V6. Well took my car in to have it looked at, got another loaner, 09 sonata I4, same knock, service couldn't replicate problem with my car.
Went ahead and got oil change, drove car home and the next day it had the same knock at startup when cold. Just took it back to dealership to have them look at irregular tap/knock when warm at idle, also car still has startup knock, but just not as loud.
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