Elantra HD (2006-10) :: Rough Idle When Cold / Slight Misfire

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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Toyota - Tundra :: Intermittent Misfire Only When Engine Is Started And Cold?

2008 Tundra 5.7 only 55K miles – What is causing an intermittent misfire at startup? It’s been running great, then 2 weeks ago when I started it up I could feel a misfire. By the time I backed out of the driveway the check engine light came on. This is what I have learned so far:

•It only happens when you start the engine and the engine is NOT at operating temperature.

•The engine code always reports misfire on Cylinder #2 I put in a new plug and swapped coils but it still reports the misfire on cylinder #2.

•Once it starts to misfire it will continue to misfire until the engine is at operating temperature and you restart the engine. NOTE: You MUST restart the engine for the misfire to go away. It will be running rough, turn engine off/on once it is at operating temperature and it's as smooth as can be, no more misfire.

•One time I started the truck, I felt the misfire and drove it to a parts store to read the code. Engine was fully warm by the time I reached the parts store. I did not power off the engine, plugged in the tester and read the code which was a misfire on cylinder 2. I cleared the code and within 2-3 seconds it logged the misfire on cylinder #2 again. Cleared the code several times and it kept reporting misfire on cylinder 2. You could also feel the misfire happening. Turned engine off, started it right back up, like before no misfire, cleared the code and it no longer reported a misfire.

•This just started intermittently happening. This morning it happened again, I drove it for about 5 min, engine was about 75% it’s normal operating temperature, powered it off/on, still had the misfire. Once engine temp reached normal temp (about 9 min), I turned off engine, started it back and like before problem was gone.

What is causing this to happen?

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Toyota - Supra :: Spits / Sputters And Misfire When Engine Is Cold

Car spits and sputters when engine is cold. When engine is warm car runs fine. I believe that my cold start injector or my cold start injector time switch is bad. 7MGE Toyota Supra ....

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Ford Escape / Hybrid :: 2001 Won't Idle After Starting - Cold Engine Misfire

I'm needing cold engine misfire. 2001 escape 3.0 engine 190300 miles on it. I changed the plugs, cleaned the fuel injectors, new air filter, new fuel filter, cleaned the pcv valve and new ideal control valve. When the engine is cold it starts right up but wont idle right and misfires sputters some to but run the rpm's up and it smooths out. drop to idle and it misses. Now when the engine gets to operating temp it seems to run fine. What am I overlooking to find the problem?

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Buick - Regal :: Rough Idle / Misfire On Cold Start - Leaking Fuel Injector(s)

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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Passat (B6) :: 2006 - CEL Just Came Up / Cold Start Misfire

Bought a 2006 (later production) with 25,000 miles over the weekend. Couldn't pass up the price and the warranty (1 year left + CPO). Picked up the car Saturday at noon..... had to drive to DC for business and the CEL came on when I turned on the car this morning. I researched at lunch that it could be a cold start misfire but I am already pretty heated about this. When I get home tonight I am going to plug it in to my OBDII scanner and see what I can pull. If it is something bad.... I am giving it back to the dealership.

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Sonata NF (2006-10) :: Idle Seems To Almost Misfire When AC Is On

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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Toyota - Avalon :: 2000 - Rough Idle - Steady Misfire - Getting Codes P1150 / P0300 / P0302 / P0304 / P0306?

I have a 2000 Toyota Avalon XLS with 134k miles, engine is a v6 (3.0). It has a rough idle and a steady misfire. You can drive it sometimes and it will run perfect and you can drive it sometimes and it will misfire. I am getting codes P1150, P0300,P0302, P0304,P0306. Driving me nuts.

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Avalon 2005-12 :: Misfire Code For Cylinder 4 On 2006 Toyota

I experienced a misfire code for #4 cylinder on my 2006 Toyota Avalon approx 8,000 miles ago and replaced the three front bank coils with Beck/Arnley coils. I didn't realize they were made in china until they arrived. The car ran fine until today when I got another misfire code for the same cylinder. I still had the two old coils in the garage so I swapped out # 4 and I'm happy to report that solved the problem. My question is should I be concerned that the # 4 cylinder has gone thru two coils in 8,000 miles or chalk it up to cheap chinese crap replacement parts?

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Lexus GS 2006-11 :: GS300 Rough Idle / Misfire On Cylinder 2

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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Sonata NF (2006-10) :: 2007 V6 Misfire / Rough Idle But No Codes

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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Accent MC (2006-11) :: CEL Flashing / Rough Idle - Cylinder 1 Misfire

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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Accent MC (2006-11) :: Misfire At Idle / Buzzing Sound Coming From The Injectors

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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Accent MC (2006-11) :: Misfire At Idle In Park Or In Gear When Stopped At A Light

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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Ford Ranger / B-Series :: 2006 3.0L - Intermittent Low Compression And Misfire At Idle

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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Prius (2001-03) :: Misfire At Cold Start?

Ok after finding out I had a bad battery @ Toyota shop they also say the scan is reading an exhaust leak ( I could hear that one ) they also say there is a misfire on cold starts should I worry and what could it be or is it a misread from the other two ?

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Toyota - Camry :: 1992 - Idle Speed Is Around 2000 RPM At Cold Start

Since having my engine replaced with a newer used engine block my idle speed when I first start it up or when it is cold is around 2000rpm which lasts for about 2-3 minutes until it begins to fall to the normal range of 1200-1400 and finally to 850 or 900rpm when warm. how can I fix this or is it okay to idle at 2000rpm for a couple of minutes? is it hurting anything?

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Toyota - Camry :: Idle Speed Blocked Around 2000 RPM On Cold Startup

1992 camry 4 cylinder ... Since having my engine replaced with a used engine block my idle speed when I first start it up or when it is cold is around 2000rpm which lasts for about 2-3 minutes until it begins to fall to the normal range of 1200-1400 and finally to 850 or 900rpm when warm. how can I fix this or is it okay to idle at 2000rpm for a couple of minutes? is it hurting anything?

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Accent MC (2006-11) :: 2008 GS - Misfire On 3 Cylinders / Rough Idle And Poor Acceleration

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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