Elantra HD (2006-10) :: Rough Idle When Cold / Slight Misfire
Nov 9, 2012
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 have had some slight rough running with a cold engine and stumble <2000rpm. Finally it tripped a CEL which was read as a misfire code.
The mechanic swapped the coil and plug(recent) and no change. He did a compression test and air blew out the exhaust. So.......the car needs a valve job which entails motor removal and fixing the head and reinstall. He rough estimates this at $2000 and rate is $65/hr.
He mentioned looking at pistons and may be a bit more if rough.
This car well maintained (170,000 miles 2005 Legacy turbo wagon with manual)...
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I have a 2001 Elantra with 170K miles. well taken care of. I've been having a rough idle issue for some time now. The car idles very rough. I checked for codes and I got the cylinder 2 misfire code (P0302)...
I started out and replaced the plugs and wires, no solution...
I replaced the coil packs, no solution...
I replaced the MAP sensor, no solution...
I figured it may be no to low compression, so I did a compression test and all cylinders came back normal, still no solution...
I figured it might be a dirty injector, so I poured some seafoam in the gas tank, and no solution...
So my next step is to switch out the injector. Is there anything I am overlooking?
Here's the big thing that is happening too... Everytime I fill up the gas tank, I turn the car on and it idles even rougher. Like if you talk while sitting in the car, you sound like Chevy Chase when he is on the vibrating bed with Beverly D'Angelo in the movie vacation! LOL. It slowly goes away after 10-15 minutes of driving. All this rough running engine ONLY happens at idle, otherwise it runs very smoothly.
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2002 Hyundai Elantra GT 2.0L 140k miles
Symptoms:
- Intermittent rough idle when hot, slight shutter, surges between 700-800rmp
- Intermittent hesitation when accelerating, cylinder 2 misfire when hot and under load
- Misfires in all gears under load, mostly when under 2000rpm
- Code P0302 when scanned, no other codes
- Symptoms appeared suddenly, not gradually over time
What's been changed:
- Replaced spark plugs, little or no improvement. Old plugs looked worn, but generally in good shape with no significant deposits.
- Cleared code and swapped injectors between cylinders 1 and 2, after test drive P0302 code came back, so it seems that the injectors are good. If the injector were bad I would have expected the misfire to change from cylinder 2 to cylinder 1.
Inspection and Testing:
- Ignition System Testing
- Spark plug wires and primary coil are within specification.
- Secondary coil resistance is high on both packs. Could this be causing a problem with just cylinder 2? Is it worth replacing?
Spark Plug Wires: Specification: 5.6 Kohm/meter +- 20%Cylinder 1: 2.49 Kohm (Longest)Cylinder 2: 2.03 KohmCylinder 3: 1.64 KohmCylinder 4:1.36 Kohm (Shortest)
Primary Coil: Specification : 0.58ohms +- 10%Actual: .6 and .6
Secondary Coil: Specification: 12.2 Kohms +- 15%
Actual (Cold): 16.03K for Cylinder 2-3 pack and 15.94K for Cylinder 1-4 pack
Actual (Hot): 18.54K for Cylinder 2-3 pack and 18.44K for Cylinder 1-4 pack
Air/Fuel System Testing:Fuel system seems to check out. I do not believe the problem is fuel related. There are no obvious cracks or leaks on the intake manifold. A good spray of Carb cleaner all around the manifold causes no change in idle. I might try propane later. No obvious vacuum leaks.
Fuel Injector: Specification: 13.1-14.5 ohms
Actual: Cyl 1: 14.9, Cyl 2: 15.3, Cyl 3: 15.3, Cyl 4: 15.7
Compression Testing:Compression is not great, but within specification. Could the slightly lower compression in Cylinders 2 and 3 indicate a head gasket leak between those cylinders? Could this cause a misfire in Cylinder 2?
Dry Compression: Specification: 145-218psi, <15psi between cylinders
Actual: Cyl 1: 165, Cyl 2: 155, Cyl 3: 155, Cyl 4: 160
Oil/Coolant/Tailpipe:
- Oil looks normal, not brown or milky
- Coolant looks normal and is full, no signs of leaking (coolant has not been changed in a very long time, could a coolant flush work?)
- Exhaust looks and smells normal from tailpipe.
Sticking valve? How would I check this? Bad sensor somewhere? Doesn't a bad sensor usually throw a code?
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1991 Buick Regal, 3800 V6
Having a rough idle on a cold start. After some research and closer inspection of the vehicle, I'm quite certain I have at least one leaking injector that is flooding a cylinder and causing the car to misfire on a cold start. I'm also not at the gas mileage I should be at.
So I'm wondering, is fuel injector replacement as straightforward of a job as it looks? Any major issues I could run into in doing a replacement?
I'm planning on replacing all six injectors (I can get them for $50 each buying online with a discount code), but given that the vehicle is so old am I better off just replacing the faulty ones? I'm assuming pulling the spark plugs and seeing which cylinder is wet will tell me which I need to replace.
And one more question: Is there a way to depressurize the fuel system when I park the car for the night, thus preventing fuel (or most of it) from leaking into the engine until I get this fixed? I've read that just unscrewing the gas cap can depressurize the system.
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I just bought a 2008 Elantra SE with 26K miles. So far, I've really enjoyed it, except for, at times, it does vibrate somewhat during idle.
I took it to the nearest Hyundai dealer, and they clipped the throttle cables to the inside of the firewall. This did make some improvement, but I still feel vibration during idle when the engine is warm (doesn't seem to as long as RPMs are up). It's almost as if the idle is set a little too low.
Maybe this is just normal vibration? It's not too bad, just noticeable. Can idle in these cars be adjusted? It seems the car is too new to have clogged fuel injectors. Everything else about driving it feels great, acceleration, etc. Do you think using a higher octane gas would work?
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I've been chasing a problem all summer. Began with crappy batteries dying intermittently. I replaced the batteries, FICM, finally cleaned EGR valve and replaced ICP with pigtail. The problem is still persistent. Basically a rough idle, puff of whit smoke on cold startup, rough running at around 1500 rpms( driving at 50 mph). The ICP was soaked in oil so i was confident replacing it would finally cure my issues. It actually got worse with the rough idle turning to a surging idle and quite rumbly at 50 mph speed. I guess its time to look to injector issues but i thought id check if after replacing icp/ cleaning egr. I also have a slight exhaust leak at turbo out that i can see. The clamp is not seated properly. This after turbo connection to exhaust.
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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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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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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 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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Today I went and test drove a used 2006 Dodge Stratus SXT from a private party. Everything about the car was great except it had a bit of a rough idle; there was a slight sputtering noise when not in motion, and the car itself vibrated very slightly. It didn't bother me too much while I was driving because it accelerated and shifted fine and the engine sounded very strong, otherwise.
When the test drive was over I pointed out the noise to the owner, and he admitted that he had mis-timed the timing belt slightly which was causing the sputtering (he is a mechanic and replaced it himself). I was worried about this, but I did some research when I got home and learned that this model of Stratus has a non-interference engine.
My question is this: should that timing belt be a deal breaker for me? Will this cause major mechanical issues down the road? I know it will reduce power but I only really need the car to commute, so I don't mind if I'm not toe-to-toe with a Challenger. I'm just worried it will eventually cause a costly problem.
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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 own a 2010 elantra. I'm going through plugs like crazy. I've changed it twice and the dealer has changed them twice for a total of 4 sets. I have 64000 Kms on my car. The problem is rough idle when ac is on. I'm assuming drag or load on the engine makes plugs work harder.. So the last two sets of plugs the dealer showed me the plug and the white spark plug casing was burned through? Kinda getting sick of the bandage approach the dealer is throwing at me. He said if it happens again which I'm sure it will they will sort it out in more detail to find the cause.
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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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Have a 2009 Elantra 4 door, manual. It is at 52000 kilometers and recently in the spring changed the oil, I run Full synthetic.
Lately its been really hot and the following problem occurs, no engine light or anything. But if I start the car cold it idles no problem, nice an smooth, If I go out for a 30min drive, come back and let it idle its rough. Not crazy rough but its rougher than it should be. I have no power issues, it pulls well, never stalls. If I shut it down and wait a few hours, engine still hot, but not super hot, start her up and runs well, no rough idle.
Go out for a 15-20 min drive and park it, idles rough. I checked the usual, wires, plugs, pvc valve seems good. Engine temp is normal also. I did some searches on the site but come up mostly with cold idle issues, not great when cold not so when hot.
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I have 114,00 miles on my car. Plugs changed and decarbonization done at 99,000 as well as ECM reprogram or update ($99). Anyway, when my car sits overnight and starts it is getting a rough high idle until I feather the pedal or give it a minute or 2 and it is fine. It is warm now in the 70's and this just started. I had it to the dealer for oil change and they looked at it. There are no codes, they recommended changing the plugs and doing a decarb again. So I told them if I need plugs there is something wrong, Iridium OEM were installed.
Anyway, they suggested changing the throttle body since it has new sensors. I have have the TPS replaced before when engine was surging. They told me there are 2 sensors and one could be bad in throttle body. I don't get it, I use Hyundai air filter now and change every 15,000 miles and get oil changes regularly and they use Quaker State Synthetic blend. I am wondering if maybe I have a faulty PCV? I don't think that has been changed. Don't even know what the interval is. Previously I was told there was none, but I disagree.
What would cause me to get carbon build up like they keep telling me? I don't want trial and error and throw parts and money at it since there are no codes. I was going to drive it til it throws a code. I do highway driving in suburban area, mostly 65 mph. The car runs good, still the intermittent hard downshift when slowing down but nothing like before the tranny was replaced.
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I have a 2010 Elantra and noticed after I start it when it's cold the rpm is about 1800rpm but doesn't drop. I never really payed attention on this car but my other cars would drop after a minute or so. Is this normal on the elantra or is something wrong?
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My idle seems to always be somewhat rough whenever I put the heat on in cold weather. While in drive I'll come to a red light, heat will be on and I'll stop. The. my idle will bounce down then back up. I shut heat off to test and it only does it while heats on.
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